Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely bee...Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely been produced through the modulation of their structure and composition.In this study,a series of bimetallic nickel-iron phosphide(Ni_(x)Fe_(2-x)P,where 0<x<2)cocatalysts with controllable structures and overpotentials were designed by adjusting the atomic ratio of Ni/Fe onto nonmetallic elemental red phosphorus(RP)for the photocatalytic selective oxidation of benzyl alcohol(BA)coupled with hydrogen production.The catalysts exhibited an outstanding photocatalytic activity for benzaldehyde and a high H_(2)yield.The RP regulated by bimetallic phosphide cocatalysts(Ni_(x)Fe_(2-x)P)demonstrated higher photocatalytic oxidation-reduction activity than that regulated by monometallic phosphide cocatalysts(Ni_(2)P and Fe2P).In particular,the RP regulated by Ni_(1.25)Fe_(0.75)P exhibited the best photocatalytic performance.In addition,experimental and theoretical calculations further illustrated that Ni_(1.25)Fe_(0.75)P,with the optimized electronic structure,possessed good electrical conductivity and provided strong adsorption and abundant active sites,thereby accelerating electron migration and lowering the reaction energy barrier of RP.This finding offers valuable insights into the rational design of highly effective cocatalysts aimed at optimizing the photocatalytic activity of composite photocatalysts.展开更多
The development of stable and efficient non-noble metal cocatalysts has arisen as a promising yet challenging endeavor in the context of photocatalytic overall water splitting.In this study,NiCo alloy cocatalysts were...The development of stable and efficient non-noble metal cocatalysts has arisen as a promising yet challenging endeavor in the context of photocatalytic overall water splitting.In this study,NiCo alloy cocatalysts were synthesized with nickel/cobalt metal organic framework(NiCo-MOF)as source of nickel and cobalt.Systematic characterization results demonstrate the successful deposition of alloy cocatalysts onto the surface of SrTiO_(3).The prepared SrTiO_(3)loaded NiCo-alloy can generate hydrogen and oxygen in a stoichiometric ratio for photocatalytic overall water splitting,achieving an apparent quantum yield of 11.9%at 350±10 nm.Theoretical calculations indicate that the introduction of cobalt has a beneficial regulatory effect on the hydrogen evolution sites of Ni,reducing the free energy of H adsorption.The synergistic catalytic effect of bimetallic catalysts contributes to enhancing photocatalytic activity and stability.This study offers constructive insights for the development of high-efficiency and cost-effective cocatalyst systems.展开更多
Negatively charged open-framework metal sulfides(NOSs),taking advantages of the characteristics of excellent visible light absorption,easily exchanged cations,and abundant active sites,hold significant promise as high...Negatively charged open-framework metal sulfides(NOSs),taking advantages of the characteristics of excellent visible light absorption,easily exchanged cations,and abundant active sites,hold significant promise as highly efficient photocatalysts for hydrogen evolution.However,their applications in photocatalytic hydrogen evolution(PHE)are infrequently documented and the corresponding photocatalytic mechanism has not yet been explored.Herein,we excavated a novel NOS photocatalyst of(Me_(2)NH_(2))_(6)In_(10)S_(18)(MIS)with a three-dimensional(3D)structure,and successfully incorporated divalent Co(Ⅱ)and metal Co(0)into its cavities via the convenient cation exchange-assisted approach to regulate the critical steps of photocatalytic reactions.As the introduced Co(0)allows for more efficient light utilization and adroitly surficial hydrogen desorption,and meanwhile acts as the‘electron pump’for rapid charge transfer,Co(0)-modified MIS delivers a surprising PHE activity in the initial stage of photocatalysis.With the prolonging of illumination,metal Co(0)gradually escapes from MIS framework,resulting in the decline of PHE performance.By stark contrast,the incorporated Co(Ⅱ)can establish a strong interaction with MIS framework,and simultaneously capture photogenerated electrons from MIS to produce Co(0),which constructs a stable photocatalytic system as well as provides additional channels for spatially separating photogenerated carriers.Thus,Co(Ⅱ)-modified MIS exhibits a robust and highly stable PHE activity of~4944μmol/g/h during the long-term photocatalytic reactions,surpassing most of the previously reported In–S framework photocatalysts.This work represents a breakthrough in the study of PHE performance and mechanism of NOS-based photocatalysts,and sheds light on the design of vip confined NOS-based photocatalysts towards high-efficiency solar-to-chemical energy conversion.展开更多
Photocatalysts are essential for the preparation of wanted fine chemical and biomedical intermediates via visible photocatalysis,but existing photocatalysts with low catalytic efficiency limit their wide applications....Photocatalysts are essential for the preparation of wanted fine chemical and biomedical intermediates via visible photocatalysis,but existing photocatalysts with low catalytic efficiency limit their wide applications.Herein,CdS/Ti_(3)C2T_(x)/MBI nanocomposites have been successfully fabricated through anchoring reduction cocatalyst Ti_(3)C_(2)T_(x) with electron-drawing ability and oxidation cocatalyst 2-mercaptobenzimidazole(MBI)with hole-capturing capacity on CdS nanoparticles.The Ti_(3)C_(2)T_(x) and MBI of CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites can extract electrons and holes from CdS nanoparticles to come true electron-hole separation,respectively.Moreover,the electron-drawing and hole-capturing abilities of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites depend on Ti_(3)C_(2)T_(x) and MBI contents,and the quantifiable electron and hole transfers finally determine photocatalytic efficiency of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites.The transient photocurrent density of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites is 6-fold higher than that of the CdS nanoparticles.The CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites with strong electron-hole separation capability exhibit outstanding visible photocatalytic organic transformation properties.The CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites produce(E)-N-benzyl-1-phenylmethylimine in~96%yield(~8000μmol·g^(-1)·h^(-1)),which is 3-fold higher than the CdS nanoparticles(~2500μmol·g^(-1)·h^(-1),30%).This work provides a new strategy for constructing efficient and stable photocatalysts that can be used for efficient visible light-driven organic transformations.展开更多
Photocatalytic hydrogen(H_(2))production using solar energy is a cutting-edge green technology that holds great potential for addressing the urgent fuel and environmental crises[1–3].To achieve high-efficiency H_(2) ...Photocatalytic hydrogen(H_(2))production using solar energy is a cutting-edge green technology that holds great potential for addressing the urgent fuel and environmental crises[1–3].To achieve high-efficiency H_(2) production,cocatalyst modification is commonly employed to provide active sites for the hydrogen evolution reaction(HER)[4,5].In this context,the kinetics of hydrogen adsorption and desorption at these active sites play a crucial role in enhancing overall photocatalytic H_(2) production efficiency.However,the H adsorption/desorption kinetics often exhibit a trade-off,presenting a significant challenge in achieving an optimal equilibrium between Hads and Hdes in many cocatalyst systems.Therefore,fine-tuning the active sites to optimize the H_(2) evolution kinetics is essential for improving photocatalytic activity[6].展开更多
BiVO_(4)is an ideal photocatalysts for H_(2)O_(2)generation due to its suitable band edge.In practice,however,the photocatalytic performance of BiVO_(4)is substantially low owing to the slow kinetics of 2e^(-)O_(2)red...BiVO_(4)is an ideal photocatalysts for H_(2)O_(2)generation due to its suitable band edge.In practice,however,the photocatalytic performance of BiVO_(4)is substantially low owing to the slow kinetics of 2e^(-)O_(2)reduction(2e^(-)ORR)and water oxidation(WOR)processes.To solve the problems,in this work,the AuPd alloy cocatalyst and the NiOOH cocatalys were modified on the electron(010)facets and the(110)hole facet of BiVO_(4)by photodeposition method.The designed AuPd/BiVO_(4)/NiOOH(0.5%)photocatalyst showed prominent photocatalytic H_(2)O_(2)production activity of 289.3μmmol_·L^(-1)with an AQE value of 0.89%at 420 nm,which was increased by 40 times compared with the BiVO_(4)sample(7.1μmmol_?L^(-1)).The outstanding photocatalytic activity of the AuPd/BiVO_(4)/NiOOH photocatalyst can be attributed to the synergistic effect of AuPd and NiOOH cocatalysts,which promoted the kinetics of oxygen reduction and water oxidation,and concurrently facilitated the charge separation.The present strategy of dual-cocatalyst rational assembly on different facets of BiVO_(4)provides an insight into explore efficient BiVO_(4)-based materials for H_(2)O_(2)production.展开更多
Facing the dual challenges of environmental pollution and energy crisis,photocatalytic water splitting for hydrogen(H_(2))production has emerged as a promising strategy to convert solar energy into storable chemical e...Facing the dual challenges of environmental pollution and energy crisis,photocatalytic water splitting for hydrogen(H_(2))production has emerged as a promising strategy to convert solar energy into storable chemical energy.In this work,the medium-entropy metal sulfides((FeCoNi)S_(2))as cocatalysts are successfully anchored onto protonated g-C_(3)N_(4)nanosheets(HCN NSs)to fabricated(FeCo-Ni)S_(2)-HCN composite via a solvothermal method.The photocatalytic hydrogen production rate of(FeCoNi)S_(2)-HCN composite reaches 2996μmol·h^(-1)·g^(-1),representing 83.22,9.16,and 1.34-fold enhancements compared to HCN(36μmol·h^(-1)·g^(-1)),FeS_(2)-HCN(327μmol·h^(-1)·g^(-1))and(FeCo)S_(2)-HCN(2240μmol·h^(-1)·g^(-1)).The apparent quantum efficiency of(FeCoNi)S_(2)-HCN composite attains 12.29% at λ=370 nm.Comprehensive characterizations and experimental analyses reveal that the superior photocatalytic performance stems from three synergistic mechanisms:(1)The curled-edge lamellar morphology of HCN nanosheets provides a large specific surface area,which enhances light absorption,facilitates electron transfer,and promotes cocatalyst loading.(2)(FeCoNi)S_(2)as cocatalyst expands the light absorption range and capacity,accelerates the separation and transfer of electron-hole pairs,and creates abundant active sites to trap photogenerated carriers for surface hydrogen evolution reactions.(3)The synergistic interactions among multiple metallic elements(Fe,Co and Ni)further enhance surface activity,increase photogenerated carrier density,and reduce charge transport resistance,ultimately optimizing hydrogen production efficiency.展开更多
Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocat...Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.展开更多
Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates th...Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates the recombination of photogenerated carriers.Consequently,the development of efficient strategies for the consumption of photogenerated holes has emerged as a critical challenge in the field of photoelectrochemical cathodic protection technology.In this paper,TiO_(2)/TiOBr heterojunction photoelectrode was firstly prepared by simple hydrothermal method,and NiCo-LDH(layered double hydroxide)was further deposited on TiO_(2)/TiOBr to obtain TiO_(2)/TiOBr/NiCo-LDH photoelectrode.The construction of a heterojunction between TiO_(2)and TiOBr promotes the separation of photogenerated carriers,while the deposition of NiCo-LDH reduces the overpotential for hole oxidation.Hence,the photoinduced potential drop and photoinduced current density of TiO_(2)/TiOBr/NiCo-LDH photoelectrode coupled with 316 L stainless steel in 3.5 wt%NaCl under simulated sunlight irradiation can be up to 303 mV and 25.87μA/cm^(2),respectively.This study provides a new idea for the design and preparation of TiO_(2)-based photoelectrodes with excellent photocathodic protection under visible light.展开更多
By harnessing the power of MoS_(2) as a cocatalyst to enhance electron transfer and charge carrier separation,a groundbreaking two-in-one redox photocatalytic system was developed.This innovative system integrated 2D ...By harnessing the power of MoS_(2) as a cocatalyst to enhance electron transfer and charge carrier separation,a groundbreaking two-in-one redox photocatalytic system was developed.This innovative system integrated 2D MoS_(2) nanosheets onto hydrangea-like Zn_(3)In_(2)S_(6) nanosheets,forming a 2D/3D heterostructure that established a stable and intimate interface.This unique architecture significantly improved cooperative photocatalytic performance,enabling the simultaneous production of hydrogen and benzaldehyde under light irradiation≥420 nm.Notably,the system achieved remarkable yields of hydrogen(41.9 mmol g^(-1) h^(-1))and benzaldehyde(38.9 mmol g^(-1) h^(-1)),surpassing the pristine Zn_(3)In_(2)S_(6) by 22.4 times.An impressive electron-hole pair utilization rate of approximately 93%was attained,underscoring the high efficiency of this two-in-one redox system.Additionally,the targeted 10 wt%-MoS_(2) loaded Zn_(3)In_(2)S_(6)(10MZ)nanohybrids at 400 nm obtained an apparent quantum yield(AQY)value of 17.66%without sacrificial agents or noble metals.The exceptional performance was attributed to improved charge carrier separation and reduced recombination,facilitated by cocatalyst integration and evidenced via photoluminescence,photoelectrochemical and Kelvin probe force microscopy measurements.This work highlighted the critical role of two-in-one redox-functioning heterojunctions in optimizing electron-hole pair utilization,offering a promising approach for sustainable energy production and organic synthesis.By demonstrating the potential for efficient,simultaneous generation of valuable chemicals and fuels,this research paves the way for the development of next-generation photocatalytic systems.展开更多
Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as ...Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.展开更多
Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydroge...Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light irradiation.In this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and challenges.Subsequently,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(e.g.metals,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(e.g.thickness,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement effects.In the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be proposed.The applications of MoS_(2) cocatalyst in the overall water splitting are also expected.This review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.展开更多
g-C3N4 is a metal-free semiconductor and a potential candidate for photocatalytic H2 production,however,the drawbacks,rapid recombination rate and limited migration efficiency of photogenerated carriers,restrict its p...g-C3N4 is a metal-free semiconductor and a potential candidate for photocatalytic H2 production,however,the drawbacks,rapid recombination rate and limited migration efficiency of photogenerated carriers,restrict its photocatalytic activity.Herein,Co(II)as a hole cocatalyst modified P-doped g-C3N4 were successfully prepared to ameliorate the separation efficiency of photoinduced carriers and enhance the photocatalytic hydrogen production.The photocatalytic results demonstrated that the P-doped g-C3N4(PCN)exhibited higher photocatalytic activity compared with pure g-C3N4,while Co(II)/PCN photocatalyst exhibited further enhancement of photocatalytic performance.The proposed possible mechanism based on various characterizations is that P-doping can modulate the electronic structure of g-C3N4 to boost the separation of photogenerated-e-and h+;while the synergistic effect of both Co(II)(as hole cocatalyst)and Pt(as electron cocatalyst)can not only lead to the directional shunting of photogenerated e+-h?pairs,but further accelerate the photogenerated electrons transfer to Pt in order to join the photocatalytic reduction process for hydrogen evolution.As a result,the transportation and separation of photoinduced carriers were accelerated to greatest extent in the Pt/Co(II)/PCN photocatalyst.展开更多
2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricte...2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricted by the recombination of photocarriers.We find that cobalt sulfide(CoS_(2))as a cocatalyst can promote g-C_(3)N_(4)nanosheets(NSs)to realize very efficient photocatalytic H_(2)generation.The prepared CoS_(2)/g-C_(3)N_(4)hybrids display highly boosted photocatalytic H_(2)generation performance and outstanding cycle stability.The optimized 7%-CoS_(2)/g-C_(3)N_(4)hybrids show a much improved photocatalytic H_(2)generation rate of 36.2μmol-1h-1,which is about 180 times as much as bare g-C_(3)N_(4)(0.2μmol-1h-1).In addition,the apparent quantum efficiency(AQE)of all the samples was computed under light atλ=370 nm,in which the AQE of 7%-CoS_(2)/g-C_(3)N_(4)hybrids is up to 5.72%.The experimental data and the DFT calculation suggest that the CoS_(2)/g-C_(3)N_(4)hybrid’s excellent HER activity is attributable to the lower overpotential and the smaller Co-H bond activation energy for HER.Accordingly,the CoS_(2)cocatalyst loading effectively boosts the photocatalytic performance of g-C_(3)N_(4)for H_(2)evolution.The project promotes fast development of high-efficiency photocatalysts and low-cost for photocatalytic H_(2)generation.展开更多
Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renew...Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renewable energy.The key to efficient conversion of solar-chemical energy is the design of an efficient structure for high charge separation and transportation.Therefore,cocatalysts are necessary in boosting photocatalytic H2 evolution.To date,semiconductor photocatalysts have been modified by various cocatalysts due to the extended light harvest,enhanced charge carrier separation efficiency and improved stability.This review focuses on recent developments of cocatalysts in photocatalytic H2 evolution,the roles and mechanism of the cocatalysts are discussed in detail.The cocatalysts can be divided into the following categories:metal/alloy cocatalysts,metal phosphides cocatalysts,metal oxide/hydroxide cocatalysts,carbon-based cocatalysts,dual cocatalysts,Z-scheme cocatalysts and MOFs cocatalysts.The future research and forecast for photocatalytic hydrogen generation are also suggested.展开更多
Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance...Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation(λ>420 nm).The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4,which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation.The hydrogen evolution rate reached^305.4μmol h^-1 g^-1,which is about three times higher than that of pristine g-C3N4,and the apparent quantum yield(AQY)was^0.45%atλ=420.Furthermore,the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate,even after five cycles under visible-light irradiation.Finally,a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.展开更多
Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst....Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.展开更多
Photocatalysis is believed to be one of the best methods to realize sustainable H2 production. However, achieving this through heterogeneous photocatalysis still remains a great challenge owing to the absence of activ...Photocatalysis is believed to be one of the best methods to realize sustainable H2 production. However, achieving this through heterogeneous photocatalysis still remains a great challenge owing to the absence of active sites, sluggish surface reaction kinetics, insufficient charge separation, and a high thermodynamic barrier. Therefore, cocatalysts are necessary and of great significance in boosting photocatalytic H2 generation. This review will focus on the promising and appealing low-cost Ni-based H2-generation cocatalysts as the alternatives for the high-cost and low-abundance noble metal cocatalysts. Special emphasis has been placed on the design principle, modification strategies for further enhancing the activity and stability of Ni-based cocatalysts, and identification of the exact active sites and surface reaction mechanisms. Particularly, four types of modification strategies based on increased light harvesting, enhanced charge separation, strengthened interface interaction, and improved electrocatalytic activity have been thoroughly discussed and compared in detail. This review may open a new avenue for designing highly active and durable Ni-based cocatalysts for photocatalytic H2 generation.展开更多
Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporo...Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic impact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3%(mole ratio of Ni^2+) NiSx cocatalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 μmol h^-1 g^-1 which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.展开更多
Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic effic...Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic efficiency and its practical application.Cocatalyst engineering is an effective strategy to spatially separate photogenerated charge carriers.In this work,noble-metal-free MoSand CoOcocatalysts are loaded on CdS nanorods by a two-step photodeposition method.The MoSfunctions as the reduction cocatalyst to trap electrons and Co Oas the oxidation cocatalyst to trap holes.Transmission electron microscopy(TEM),inductively coupled plasma(ICP),X-ray photoelectron spectroscopy(XPS)and MottSchottky results demonstrate the effectiveness of photodeposition for loading MoSand CoOdual cocatalysts on CdS and their impact on the photochemical properties.The optimized CdS-MoS-CoOcomposite exhibits a high photocatalytic H-production rate of 7.4 mmol g^(-1)h^(-1)and an apparent quantum efficiency(QE)of 7.6%at 420 nm.Further analysis on time-resolved photoluminescence(TRPL)indicates that the introduction of dual cocatalysts greatly prolongs the lifetime of photogenerated charge carriers and deceases the charge recombination rates,consequently leading to superior photocatalytic H-production performance.This work provides a facile and effective strategy for the construction of highly efficient dual-cocatalyst-modified CdS photocatalyst for high-performance photocatalytic Hproduction.展开更多
文摘Although bimetallic phosphide cocatalysts have attracted considerable interest in photocatalysis research owing to their advantageous thermodynamic characteristics,superstable and efficient cocatalysts have rarely been produced through the modulation of their structure and composition.In this study,a series of bimetallic nickel-iron phosphide(Ni_(x)Fe_(2-x)P,where 0<x<2)cocatalysts with controllable structures and overpotentials were designed by adjusting the atomic ratio of Ni/Fe onto nonmetallic elemental red phosphorus(RP)for the photocatalytic selective oxidation of benzyl alcohol(BA)coupled with hydrogen production.The catalysts exhibited an outstanding photocatalytic activity for benzaldehyde and a high H_(2)yield.The RP regulated by bimetallic phosphide cocatalysts(Ni_(x)Fe_(2-x)P)demonstrated higher photocatalytic oxidation-reduction activity than that regulated by monometallic phosphide cocatalysts(Ni_(2)P and Fe2P).In particular,the RP regulated by Ni_(1.25)Fe_(0.75)P exhibited the best photocatalytic performance.In addition,experimental and theoretical calculations further illustrated that Ni_(1.25)Fe_(0.75)P,with the optimized electronic structure,possessed good electrical conductivity and provided strong adsorption and abundant active sites,thereby accelerating electron migration and lowering the reaction energy barrier of RP.This finding offers valuable insights into the rational design of highly effective cocatalysts aimed at optimizing the photocatalytic activity of composite photocatalysts.
基金supported by the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.52488201)the National Natural Science Foundation of China(No.52376209)+1 种基金the China Postdoctoral Science Foundation(Nos.2020T130503 and 2020M673386)China Fundamental Research Funds for the Central Universities.
文摘The development of stable and efficient non-noble metal cocatalysts has arisen as a promising yet challenging endeavor in the context of photocatalytic overall water splitting.In this study,NiCo alloy cocatalysts were synthesized with nickel/cobalt metal organic framework(NiCo-MOF)as source of nickel and cobalt.Systematic characterization results demonstrate the successful deposition of alloy cocatalysts onto the surface of SrTiO_(3).The prepared SrTiO_(3)loaded NiCo-alloy can generate hydrogen and oxygen in a stoichiometric ratio for photocatalytic overall water splitting,achieving an apparent quantum yield of 11.9%at 350±10 nm.Theoretical calculations indicate that the introduction of cobalt has a beneficial regulatory effect on the hydrogen evolution sites of Ni,reducing the free energy of H adsorption.The synergistic catalytic effect of bimetallic catalysts contributes to enhancing photocatalytic activity and stability.This study offers constructive insights for the development of high-efficiency and cost-effective cocatalyst systems.
基金financial supports provided by the Natural Science Foundation of Fujian Province(No.2024J01195)the National Nature Science Foundation of China(No.21905279)+1 种基金Sanming University(Nos.22YG11 and PYT2201)the Education Scientific Research Project of Youth Teachers in the Education Department of Fujian Province(No.JAT220351).
文摘Negatively charged open-framework metal sulfides(NOSs),taking advantages of the characteristics of excellent visible light absorption,easily exchanged cations,and abundant active sites,hold significant promise as highly efficient photocatalysts for hydrogen evolution.However,their applications in photocatalytic hydrogen evolution(PHE)are infrequently documented and the corresponding photocatalytic mechanism has not yet been explored.Herein,we excavated a novel NOS photocatalyst of(Me_(2)NH_(2))_(6)In_(10)S_(18)(MIS)with a three-dimensional(3D)structure,and successfully incorporated divalent Co(Ⅱ)and metal Co(0)into its cavities via the convenient cation exchange-assisted approach to regulate the critical steps of photocatalytic reactions.As the introduced Co(0)allows for more efficient light utilization and adroitly surficial hydrogen desorption,and meanwhile acts as the‘electron pump’for rapid charge transfer,Co(0)-modified MIS delivers a surprising PHE activity in the initial stage of photocatalysis.With the prolonging of illumination,metal Co(0)gradually escapes from MIS framework,resulting in the decline of PHE performance.By stark contrast,the incorporated Co(Ⅱ)can establish a strong interaction with MIS framework,and simultaneously capture photogenerated electrons from MIS to produce Co(0),which constructs a stable photocatalytic system as well as provides additional channels for spatially separating photogenerated carriers.Thus,Co(Ⅱ)-modified MIS exhibits a robust and highly stable PHE activity of~4944μmol/g/h during the long-term photocatalytic reactions,surpassing most of the previously reported In–S framework photocatalysts.This work represents a breakthrough in the study of PHE performance and mechanism of NOS-based photocatalysts,and sheds light on the design of vip confined NOS-based photocatalysts towards high-efficiency solar-to-chemical energy conversion.
文摘Photocatalysts are essential for the preparation of wanted fine chemical and biomedical intermediates via visible photocatalysis,but existing photocatalysts with low catalytic efficiency limit their wide applications.Herein,CdS/Ti_(3)C2T_(x)/MBI nanocomposites have been successfully fabricated through anchoring reduction cocatalyst Ti_(3)C_(2)T_(x) with electron-drawing ability and oxidation cocatalyst 2-mercaptobenzimidazole(MBI)with hole-capturing capacity on CdS nanoparticles.The Ti_(3)C_(2)T_(x) and MBI of CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites can extract electrons and holes from CdS nanoparticles to come true electron-hole separation,respectively.Moreover,the electron-drawing and hole-capturing abilities of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites depend on Ti_(3)C_(2)T_(x) and MBI contents,and the quantifiable electron and hole transfers finally determine photocatalytic efficiency of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites.The transient photocurrent density of the CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites is 6-fold higher than that of the CdS nanoparticles.The CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites with strong electron-hole separation capability exhibit outstanding visible photocatalytic organic transformation properties.The CdS/Ti_(3)C_(2)T_(x)/MBI nanocomposites produce(E)-N-benzyl-1-phenylmethylimine in~96%yield(~8000μmol·g^(-1)·h^(-1)),which is 3-fold higher than the CdS nanoparticles(~2500μmol·g^(-1)·h^(-1),30%).This work provides a new strategy for constructing efficient and stable photocatalysts that can be used for efficient visible light-driven organic transformations.
文摘Photocatalytic hydrogen(H_(2))production using solar energy is a cutting-edge green technology that holds great potential for addressing the urgent fuel and environmental crises[1–3].To achieve high-efficiency H_(2) production,cocatalyst modification is commonly employed to provide active sites for the hydrogen evolution reaction(HER)[4,5].In this context,the kinetics of hydrogen adsorption and desorption at these active sites play a crucial role in enhancing overall photocatalytic H_(2) production efficiency.However,the H adsorption/desorption kinetics often exhibit a trade-off,presenting a significant challenge in achieving an optimal equilibrium between Hads and Hdes in many cocatalyst systems.Therefore,fine-tuning the active sites to optimize the H_(2) evolution kinetics is essential for improving photocatalytic activity[6].
基金Funded by the National Natural Science Foundation of China(Nos.22178276,22178275,U22A20147,and 22075220)the Natural Science Foundation of Hubei Province of China(No.2022CFA001)。
文摘BiVO_(4)is an ideal photocatalysts for H_(2)O_(2)generation due to its suitable band edge.In practice,however,the photocatalytic performance of BiVO_(4)is substantially low owing to the slow kinetics of 2e^(-)O_(2)reduction(2e^(-)ORR)and water oxidation(WOR)processes.To solve the problems,in this work,the AuPd alloy cocatalyst and the NiOOH cocatalys were modified on the electron(010)facets and the(110)hole facet of BiVO_(4)by photodeposition method.The designed AuPd/BiVO_(4)/NiOOH(0.5%)photocatalyst showed prominent photocatalytic H_(2)O_(2)production activity of 289.3μmmol_·L^(-1)with an AQE value of 0.89%at 420 nm,which was increased by 40 times compared with the BiVO_(4)sample(7.1μmmol_?L^(-1)).The outstanding photocatalytic activity of the AuPd/BiVO_(4)/NiOOH photocatalyst can be attributed to the synergistic effect of AuPd and NiOOH cocatalysts,which promoted the kinetics of oxygen reduction and water oxidation,and concurrently facilitated the charge separation.The present strategy of dual-cocatalyst rational assembly on different facets of BiVO_(4)provides an insight into explore efficient BiVO_(4)-based materials for H_(2)O_(2)production.
文摘Facing the dual challenges of environmental pollution and energy crisis,photocatalytic water splitting for hydrogen(H_(2))production has emerged as a promising strategy to convert solar energy into storable chemical energy.In this work,the medium-entropy metal sulfides((FeCoNi)S_(2))as cocatalysts are successfully anchored onto protonated g-C_(3)N_(4)nanosheets(HCN NSs)to fabricated(FeCo-Ni)S_(2)-HCN composite via a solvothermal method.The photocatalytic hydrogen production rate of(FeCoNi)S_(2)-HCN composite reaches 2996μmol·h^(-1)·g^(-1),representing 83.22,9.16,and 1.34-fold enhancements compared to HCN(36μmol·h^(-1)·g^(-1)),FeS_(2)-HCN(327μmol·h^(-1)·g^(-1))and(FeCo)S_(2)-HCN(2240μmol·h^(-1)·g^(-1)).The apparent quantum efficiency of(FeCoNi)S_(2)-HCN composite attains 12.29% at λ=370 nm.Comprehensive characterizations and experimental analyses reveal that the superior photocatalytic performance stems from three synergistic mechanisms:(1)The curled-edge lamellar morphology of HCN nanosheets provides a large specific surface area,which enhances light absorption,facilitates electron transfer,and promotes cocatalyst loading.(2)(FeCoNi)S_(2)as cocatalyst expands the light absorption range and capacity,accelerates the separation and transfer of electron-hole pairs,and creates abundant active sites to trap photogenerated carriers for surface hydrogen evolution reactions.(3)The synergistic interactions among multiple metallic elements(Fe,Co and Ni)further enhance surface activity,increase photogenerated carrier density,and reduce charge transport resistance,ultimately optimizing hydrogen production efficiency.
文摘Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.
基金financially supported by the Natural Science Foundation of Shandong(No.ZR2023QD152)the National Natural Science Foundation of China(No.42476212).
文摘Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates the recombination of photogenerated carriers.Consequently,the development of efficient strategies for the consumption of photogenerated holes has emerged as a critical challenge in the field of photoelectrochemical cathodic protection technology.In this paper,TiO_(2)/TiOBr heterojunction photoelectrode was firstly prepared by simple hydrothermal method,and NiCo-LDH(layered double hydroxide)was further deposited on TiO_(2)/TiOBr to obtain TiO_(2)/TiOBr/NiCo-LDH photoelectrode.The construction of a heterojunction between TiO_(2)and TiOBr promotes the separation of photogenerated carriers,while the deposition of NiCo-LDH reduces the overpotential for hole oxidation.Hence,the photoinduced potential drop and photoinduced current density of TiO_(2)/TiOBr/NiCo-LDH photoelectrode coupled with 316 L stainless steel in 3.5 wt%NaCl under simulated sunlight irradiation can be up to 303 mV and 25.87μA/cm^(2),respectively.This study provides a new idea for the design and preparation of TiO_(2)-based photoelectrodes with excellent photocathodic protection under visible light.
基金support provided by the Ministry of Higher Education Malaysia under the Xiamen University Malaysia.-Fundamental Research Grant Scheme(FRGS)(Ref no.FRGS/1/2024/TK08/XMU/02/1)supported by the PETRONAS-Academia Collaboration Dialogue(PACD 2023)grant,provided by PETRONAS Research Sdn.Bhd.(PRSB)+6 种基金the Ministry of Science,Technology and Innovation(MOSTI)Malaysia under the Strategic Research Fund(SRF)(S.22015)supported by the National Natural Science Foundation of China(Ref no:22202168)Guangdong Basic and Applied Basic Research Foundation(Ref no:2021A1515111019)the financial support from the State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University(Ref no:2023X11)supported by the Xiamen University,Embassy of the People's Republic of China in Malaysia(EENG/0045)funded by Xiamen University Malaysia Investigatorship Grant(Grant no:IENG/0038)Xiamen University Malaysia Research Fund(ICOE/0001,XMUMRF/2021-C8/IENG/0041 and XMUMRF/2025-C15/IENG/0080).
文摘By harnessing the power of MoS_(2) as a cocatalyst to enhance electron transfer and charge carrier separation,a groundbreaking two-in-one redox photocatalytic system was developed.This innovative system integrated 2D MoS_(2) nanosheets onto hydrangea-like Zn_(3)In_(2)S_(6) nanosheets,forming a 2D/3D heterostructure that established a stable and intimate interface.This unique architecture significantly improved cooperative photocatalytic performance,enabling the simultaneous production of hydrogen and benzaldehyde under light irradiation≥420 nm.Notably,the system achieved remarkable yields of hydrogen(41.9 mmol g^(-1) h^(-1))and benzaldehyde(38.9 mmol g^(-1) h^(-1)),surpassing the pristine Zn_(3)In_(2)S_(6) by 22.4 times.An impressive electron-hole pair utilization rate of approximately 93%was attained,underscoring the high efficiency of this two-in-one redox system.Additionally,the targeted 10 wt%-MoS_(2) loaded Zn_(3)In_(2)S_(6)(10MZ)nanohybrids at 400 nm obtained an apparent quantum yield(AQY)value of 17.66%without sacrificial agents or noble metals.The exceptional performance was attributed to improved charge carrier separation and reduced recombination,facilitated by cocatalyst integration and evidenced via photoluminescence,photoelectrochemical and Kelvin probe force microscopy measurements.This work highlighted the critical role of two-in-one redox-functioning heterojunctions in optimizing electron-hole pair utilization,offering a promising approach for sustainable energy production and organic synthesis.By demonstrating the potential for efficient,simultaneous generation of valuable chemicals and fuels,this research paves the way for the development of next-generation photocatalytic systems.
基金supported by the National Natural Science Foundation of China (51672089)the Industry and Research Collaborative Innovation Major Projects of Guangzhou (201508020098)+1 种基金the State Key Laboratory of Advanced Technology for Material Synthesis and Processing (Wuhan University of Technology) (2015-KF-7)the Hunan Key Laboratory of Applied Environmental Photocatalysis (Changsha University) (CCSU-XT-04)~~
文摘Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.
基金the National Natural Science Foundation of China(Nos.21975084 and 51672089)the Guangdong Provincial Applied Science and Technology Research and Development Program(No.2017B020238005)+2 种基金the Ding Ying Talent Project of South China Agricultural University for their supportthe Hong Kong Research Grant Council(RGC)General Research Fund(No.GRF1305419)for financial supportthe National Natural Science Foundation of China(Nos.51972287 and 51502269)。
文摘Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light irradiation.In this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and challenges.Subsequently,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(e.g.metals,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(e.g.thickness,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement effects.In the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be proposed.The applications of MoS_(2) cocatalyst in the overall water splitting are also expected.This review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.
基金supported by the National Natural Science Foundation of China(51672113)QingLan Project Foundation of Jiangsu Province(201611)~~
文摘g-C3N4 is a metal-free semiconductor and a potential candidate for photocatalytic H2 production,however,the drawbacks,rapid recombination rate and limited migration efficiency of photogenerated carriers,restrict its photocatalytic activity.Herein,Co(II)as a hole cocatalyst modified P-doped g-C3N4 were successfully prepared to ameliorate the separation efficiency of photoinduced carriers and enhance the photocatalytic hydrogen production.The photocatalytic results demonstrated that the P-doped g-C3N4(PCN)exhibited higher photocatalytic activity compared with pure g-C3N4,while Co(II)/PCN photocatalyst exhibited further enhancement of photocatalytic performance.The proposed possible mechanism based on various characterizations is that P-doping can modulate the electronic structure of g-C3N4 to boost the separation of photogenerated-e-and h+;while the synergistic effect of both Co(II)(as hole cocatalyst)and Pt(as electron cocatalyst)can not only lead to the directional shunting of photogenerated e+-h?pairs,but further accelerate the photogenerated electrons transfer to Pt in order to join the photocatalytic reduction process for hydrogen evolution.As a result,the transportation and separation of photoinduced carriers were accelerated to greatest extent in the Pt/Co(II)/PCN photocatalyst.
基金funding from the National Natural Science Foundation of China(No.51872173 and 51772176)Taishan Scholar Foundation of Shandong Province(No.tsqn201812068 and tspd20161006)+2 种基金Youth Innovation Technology Project of Higher School in Shandong Province(No.2019KJA013)Science and Technology Special Project of Qingdao City(No.20-3-4-3-nsh)the Opening Fund of State Key Laboratory of Heavy Oil Processing(No.SKLOP202002006)。
文摘2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricted by the recombination of photocarriers.We find that cobalt sulfide(CoS_(2))as a cocatalyst can promote g-C_(3)N_(4)nanosheets(NSs)to realize very efficient photocatalytic H_(2)generation.The prepared CoS_(2)/g-C_(3)N_(4)hybrids display highly boosted photocatalytic H_(2)generation performance and outstanding cycle stability.The optimized 7%-CoS_(2)/g-C_(3)N_(4)hybrids show a much improved photocatalytic H_(2)generation rate of 36.2μmol-1h-1,which is about 180 times as much as bare g-C_(3)N_(4)(0.2μmol-1h-1).In addition,the apparent quantum efficiency(AQE)of all the samples was computed under light atλ=370 nm,in which the AQE of 7%-CoS_(2)/g-C_(3)N_(4)hybrids is up to 5.72%.The experimental data and the DFT calculation suggest that the CoS_(2)/g-C_(3)N_(4)hybrid’s excellent HER activity is attributable to the lower overpotential and the smaller Co-H bond activation energy for HER.Accordingly,the CoS_(2)cocatalyst loading effectively boosts the photocatalytic performance of g-C_(3)N_(4)for H_(2)evolution.The project promotes fast development of high-efficiency photocatalysts and low-cost for photocatalytic H_(2)generation.
基金financially supported by the National Natural Science Foundation of China(51572295,21273285 and 21003157)Beijing Nova Program(2008B76)Science Foundation of China University of Petroleum,Beijing(KYJJ2012-06-20 and 2462016YXBS05)~~
文摘Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renewable energy.The key to efficient conversion of solar-chemical energy is the design of an efficient structure for high charge separation and transportation.Therefore,cocatalysts are necessary in boosting photocatalytic H2 evolution.To date,semiconductor photocatalysts have been modified by various cocatalysts due to the extended light harvest,enhanced charge carrier separation efficiency and improved stability.This review focuses on recent developments of cocatalysts in photocatalytic H2 evolution,the roles and mechanism of the cocatalysts are discussed in detail.The cocatalysts can be divided into the following categories:metal/alloy cocatalysts,metal phosphides cocatalysts,metal oxide/hydroxide cocatalysts,carbon-based cocatalysts,dual cocatalysts,Z-scheme cocatalysts and MOFs cocatalysts.The future research and forecast for photocatalytic hydrogen generation are also suggested.
基金financially supported by the National Key Research and Development Program of China(2017YFA0402800)the National Natural Science Foundation of China(51772285,21473170,51878004)+1 种基金the Natural Science Fund of of Anhui Province(1808085ME139)the Fundamental Research Funds for the Central Universities~~
文摘Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation(λ>420 nm).The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4,which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation.The hydrogen evolution rate reached^305.4μmol h^-1 g^-1,which is about three times higher than that of pristine g-C3N4,and the apparent quantum yield(AQY)was^0.45%atλ=420.Furthermore,the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate,even after five cycles under visible-light irradiation.Finally,a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.
基金financially supported by the National Natural Science Foundation of China (No. 51773178)
文摘Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.
基金supprted by the National Natural Science Foundation of China(51672089,51672099)Specical Funding on Applied Science and Technology in Guangdong(2017B020238005)the State Key Laboratory of Advanced Technology for Material Synthesis and Processing(Wuhan University of Technology)(2015-KF-7)~~
文摘Photocatalysis is believed to be one of the best methods to realize sustainable H2 production. However, achieving this through heterogeneous photocatalysis still remains a great challenge owing to the absence of active sites, sluggish surface reaction kinetics, insufficient charge separation, and a high thermodynamic barrier. Therefore, cocatalysts are necessary and of great significance in boosting photocatalytic H2 generation. This review will focus on the promising and appealing low-cost Ni-based H2-generation cocatalysts as the alternatives for the high-cost and low-abundance noble metal cocatalysts. Special emphasis has been placed on the design principle, modification strategies for further enhancing the activity and stability of Ni-based cocatalysts, and identification of the exact active sites and surface reaction mechanisms. Particularly, four types of modification strategies based on increased light harvesting, enhanced charge separation, strengthened interface interaction, and improved electrocatalytic activity have been thoroughly discussed and compared in detail. This review may open a new avenue for designing highly active and durable Ni-based cocatalysts for photocatalytic H2 generation.
基金the National Natural Science Foundation of China(21501137)the Hubei Natural Science Foundation for financial support(2018CFB680)Support from the Australian Research Council(ARC)through ARC Discovery projects(DP130102699,DP 130102274,DP160102627)
文摘Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic impact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3%(mole ratio of Ni^2+) NiSx cocatalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 μmol h^-1 g^-1 which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.
基金the National Science Foundation of China(Nos.22005228 and 52063028)。
文摘Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic efficiency and its practical application.Cocatalyst engineering is an effective strategy to spatially separate photogenerated charge carriers.In this work,noble-metal-free MoSand CoOcocatalysts are loaded on CdS nanorods by a two-step photodeposition method.The MoSfunctions as the reduction cocatalyst to trap electrons and Co Oas the oxidation cocatalyst to trap holes.Transmission electron microscopy(TEM),inductively coupled plasma(ICP),X-ray photoelectron spectroscopy(XPS)and MottSchottky results demonstrate the effectiveness of photodeposition for loading MoSand CoOdual cocatalysts on CdS and their impact on the photochemical properties.The optimized CdS-MoS-CoOcomposite exhibits a high photocatalytic H-production rate of 7.4 mmol g^(-1)h^(-1)and an apparent quantum efficiency(QE)of 7.6%at 420 nm.Further analysis on time-resolved photoluminescence(TRPL)indicates that the introduction of dual cocatalysts greatly prolongs the lifetime of photogenerated charge carriers and deceases the charge recombination rates,consequently leading to superior photocatalytic H-production performance.This work provides a facile and effective strategy for the construction of highly efficient dual-cocatalyst-modified CdS photocatalyst for high-performance photocatalytic Hproduction.
