Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might ...Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might take advantage of each compound and display an increased activity.In our previous study,boron doped-Cu_(3)NiBaTi_(4)O_(9)possessed a porous structure and its photocurrent response was apparent.To further verify its excellent catalytic activity,Al_(2)O_(3),and SiO_(2) were selected to replace with BaTi_(4)O_(9)to prepare different composites.The physical and chemical features of each sample were characterized with SEM,XRD,XPS,etc.to reveal their structural variations.Correspondingly,the H_(2)evolution rate was investigated with gas chromatography under the sunlight irritation.A distinct hydrogen yield was recorded with prepared samples.Further,the projected density of states analysis was taken through density functional theory calculations to appreciate the conduction band of the composite.The offered electrons during the photocatalytic process and the potential applicability of composites in the field of photocatalysis was verified.展开更多
As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol syn...As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol synthesis,In_(2)O_(3)is an ideal catalyst and has garnered significant attention.Herein,cubic In_(2)O_(3)nanoparticles were prepared via the precipitation method and evaluated for CO_(2)hydrogenation to produce methanol.During the initial 10 h of reaction,CO_(2)conversion gradually increased,accompanied by a slow decrease of methanol selectivity,and the reaction reached equilibrium after 10-20 h on stream.This activation and induction stage may be attributed to the sintering of In_(2)O_(3)nanoparticles and the creation of more oxygen vacancies on In_(2)O_(3)surfaces.Further experimental studies demonstrate that hydrogen induction created additional oxygen vacancies during the catalyst activation stage,enhancing the performance of In_(2)O_(3)catalyst for CO_(2)hydrogenation.Density functional theory calculations and microkinetic simulations further demonstrated that surfaces with higher oxygen vacancy coverages or hydroxylated surfaces formed during this induction period can enhance the reaction rate and increase the CO_(2)conversion.However,they predominantly promote the formation of CO instead of methanol,leading to reduced methanol selectivity.These predictions align well with the above-mentioned experimental observations.Our work thus provides an in-depth analysis of the induction stage of the CO_(2)hydrogenation process on In_(2)O_(3)nano-catalyst,and offers valuable insights for significantly improving the CO_(2)reactivity of In_(2)O_(3)-based catalysts while maintaining long-term stability.展开更多
Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is ...Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.展开更多
The electrochemical hydrogen evolution reaction（HER） on a non-precious electrocatalyst in an alkaline environment is of essential importance for future renewable energy. The design of advanced electrocatalysts for H...The electrochemical hydrogen evolution reaction（HER） on a non-precious electrocatalyst in an alkaline environment is of essential importance for future renewable energy. The design of advanced electrocatalysts for HER is the most important part to reduce the cost and to enhance the efficiency of water splitting. MoSis considered as one of the most promising electrocatalysts to replace the precious Pt catalyst.Herein, for the first time, we have successfully loaded MoSelectrocatalysts onto the CoOnanosheet array to catalyze HER with a low onset potential of6 mV. The high hydrogen evolution activity of MoSsupported on the CoOnanosheet array may be attributed to the increased active sites and the electronic interactions between MoSand CoO.展开更多
Al_(2)O_(3)-Y_(2)O_(3)composite powder with TiO_(2)additive was plasma sprayed to prepare Al_(2)O_(3)-Y_(2)O_(3)composite coatings.The micro structure and properties evolution of the Al_(2)O_(3)-Y_(2)O_(3)coatings dur...Al_(2)O_(3)-Y_(2)O_(3)composite powder with TiO_(2)additive was plasma sprayed to prepare Al_(2)O_(3)-Y_(2)O_(3)composite coatings.The micro structure and properties evolution of the Al_(2)O_(3)-Y_(2)O_(3)coatings during high temperature and thermal shock resistance were investigated.The results show that the micro structure of the Al_(2)O_(3)-Y_(2)O_(3)-TiO_(2)coating is more uniform than that of the Al_(2)O_(3)-Y_(2)O_(3)coating.Meanwhile,amorphous phase is formed in the two coatings.The Al_(2)O_(3)-Y_(2)O_(3)(-TiO_(2))coatings were heat treated for 2 h at temperatures of 800,1000 and 1200℃,respectively.It is found that the microstructure and properties of the two coatings have no obvious change at 800℃.Some of the amorphous phase is crystallized at1000℃,and meanwhile Y_(2)O_(3)and Al_(2)O_(3)react to form YAG phase and YAM phase.At 1200℃,all of the amorphous phases are crystallized.After heat treatment,the micro hardness of the two coatings is increased.The thermal shock resistance of the Al_(2)O_(3)-Y_(2)O_(3)system coatings can be improved by using TC4 titanium alloy as substrate and with NiCrAlY bonding layer.Moreover,the Al_(2)O_(3)-Y_(2)O_(3)-TiO_(2)coating exhibits better thermal shock resistance due to the addition of TiO_(2).展开更多
(γ’+β)two-phase Ni-Al is a promising high-temperature protective coating material used on Ni-base superalloys since it has good interfacial compatibility with superalloys due to the low Al content compared to singl...(γ’+β)two-phase Ni-Al is a promising high-temperature protective coating material used on Ni-base superalloys since it has good interfacial compatibility with superalloys due to the low Al content compared to single-phaseβ-NiA l.In this paper,we aim to improve the oxidation resistance,whereby Ni-34Al-0.1Dy,a(γ’+β)two-phase Ni-Al alloy,was treated by laser shock processing(LSP)and the oxidation behavior at 1150℃ was investigated.The results showed that after oxidation,Al_(2)O_(3)scale formed on the originalβphase of the untreated alloy with a small grain size(200-800 nm),while for the LSP-treated samples,the scale grown on the originalβphase was dominantly composed of larger Al_(2)O_(3)grains with a size of 2-3μm.The distinction was attributed to the promotion ofθ-Al_(2)O_(3)toα-Al_(2)O_(3)transformation induced by the LSP,because the dislocation density,as well as surface roughness,were increased during LSP treatment which can provide heterogeneous nucleation sites forα-Al_(2)O_(3).In addition,the larger-size Al_(2)O_(3)particles,derived from the direct conversion of needle-likeθ-Al_(2)O_(3)in the initial oxidation stage,could rapidly overspread the wholeβphase surface thus reducing the scale growth rate.展开更多
The random movement and easy recombination of photoinduced charges lead to a low conversion efficiency for photocatalytic hydrogen evolution.The cocatalyst design is a promising route to address such problem through i...The random movement and easy recombination of photoinduced charges lead to a low conversion efficiency for photocatalytic hydrogen evolution.The cocatalyst design is a promising route to address such problem through introducing an appropriate cocatalyst on the semiconductor photocatalysts to construct the high-efficiency heterojunctions.Herein,novel CoS/Nb_(2)O_(5) heterojunctions were constructed via in-situ loading CoS cocatalyst on the surface of Nb_(2)O_(5) nanosheets.Through the femtosecond-resolved transient absorption spectroscopy,the average lifetime of charge carriers for 10 wt% CoS/Nb_(2)O_(5)(159.6 ps)is drastically shortened by contrast with that of Nb_(2)O_(5)(5531.9 ps),strongly suggesting the rapid charge transfer from Nb_(2)O_(5) to CoS.The significantly improved charge-transfer capacity contributes to a high photocatalytic hydrogen evolution rate of 355µmol/h,up to 17.5 times compared with pristine Nb_(2)O_(5).This work would provide a new design platform in the construction of photocatalytic heterojunctions with high charge-transfer efficiency.展开更多
Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further ...Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.展开更多
Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer effic...Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer efficiency for photocatalysts.Herein,a new 2 D/2 D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core photocatalyst(DLWS/Nb_(2)O_(5))is designed.The atom-resolved HAADF-STEM results unravel the presence of an unusual 2 D/2 D shell/core interface in DLWS/Nb_(2)O_(5).Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra,the average lifetime of charge carriers for DLWS/Nb_(2)O_(5)(180.97 ps)is considerably shortened as compared to that of Nb_(2)O_(5)(230.50 ps),strongly indicating that the 2 D/2 D shell/core interface enables DLWS/Nb_(2)O_(5)to achieve ultrafast charge transfer from Nb_(2)O_(5)to atomic double-layer WS_(2),thus yielding a high photocatalytic H_(2)evolution rate of 237.6 mmol/h,up to10.8 times higher than that of pure Nb_(2)O_(5)nanosheet.This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.展开更多
Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(...Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.展开更多
Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silic...Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.展开更多
Here,1D bis(N-carboxymethyl)peryleneimide(H_(2)PDI),0D 1,6,7,12-tetrachloro-bis(N-carboxymethyl)peryleneimide(4Cl-H_(2)PDI),and 2D 4Cl-H_(2)PDI/graphene quantum dot(4Cl-H_(2)PDI/GQD)nanostructures are synthesized and ...Here,1D bis(N-carboxymethyl)peryleneimide(H_(2)PDI),0D 1,6,7,12-tetrachloro-bis(N-carboxymethyl)peryleneimide(4Cl-H_(2)PDI),and 2D 4Cl-H_(2)PDI/graphene quantum dot(4Cl-H_(2)PDI/GQD)nanostructures are synthesized and carefully analyzed.The effect of bay-/end-substitution and S-scheme heterojunction of PDI-based materials as main catalysts on the photocatalytic H_(2)O_(2)evolution is first studied through the oxygen reduction reaction(ORR).Under the visible-light irradiation(>420 nm),4Cl-H_(2)PDI and 4Cl-H_(2)PDI/GQD as photocatalysts exhibit the∼7 and∼16 times H_(2)O_(2)evolution rate than H_(2)PDI(1059.6 vs.2484.0 vs.160.0μM g^(−1) h^(−1)),respectively.The systematical experiments reveal that 4Cl-H_(2)PDI and 4Cl-H_(2)PDI/GQD should prefer a two-step single-electron ORR process,while H_(2)PDI may involve a 4e-water oxidation and one-step 2e-ORR process.Further experiments confirm that the bay-substitution and GQD doping of H_(2)PDI can promote the generation,transportation,and separation of photogenerated electrons and holes,and prolong the carrier lifetime.This work provides insight into PDI-based photocatalytic H_(2)O_(2)production.展开更多
The oxygen evolution reaction(OER)serves as a fundamental half–reaction in the electrolysis of water for hydrogen production,which is restricted by the sluggish OER reaction kinetics and unable to be practically appl...The oxygen evolution reaction(OER)serves as a fundamental half–reaction in the electrolysis of water for hydrogen production,which is restricted by the sluggish OER reaction kinetics and unable to be practically applied.The traditional lattice oxygen oxidation mechanism(LOM)offers an advantageous route by circumventing the formation of M-OOH^(*)in the adsorption evolution mechanism(AEM),thus enhancing the reaction kinetics of the OER but resulting in possible structural destabilization due to the decreased M–O bond order.Fortunately,the asymmetry of tetrahedral and octahedral sites in transition metal spinel oxides permits the existence of non-bonding oxygen,which could be activated by rational band structure design for direct O-O coupling,where the M–O bond maintains its initial bond order.Here,non-bonding oxygen was introduced into NiFe_(2)O_(4)via annealing in an oxygen-deficient atmosphere.Then,in-situ grown sulfate species on octahedral nickel sites significantly improved the reactivity of the non-bonding oxygen electrons,thereby facilitating the transformation of the redox center from metal to oxygen.LOM based on non-bonding oxygen(LOMNB)was successfully activated within NiFe_(2)O_(4),exhibiting a low overpotential of 206 mV to achieve a current density of 10 mA cm^(-2)and excellent durability of stable operation for over 150 h.Additionally,catalysts featuring varying band structures were synthesized for comparative analysis,and it was found that the reversible redox processes of non-bonding oxygen and the accumulation of non-bonding oxygen species containing 2p holes are critical prerequisites for triggering and sustaining the LOMNB pathway in transition metal spinel oxides.These findings may provide valuable insights for the future development of spinel-oxide-based LOM catalysts.展开更多
The modulation of charge transfer pathways within type-I heterojunctions through interfacial electric field(IEF)engineering is of critical importance in promoting photocatalytic hydrogen evolution,effectively facilita...The modulation of charge transfer pathways within type-I heterojunctions through interfacial electric field(IEF)engineering is of critical importance in promoting photocatalytic hydrogen evolution,effectively facilitating the separation of photogenerated charge carriers.In this study,we performed in-situ growth of two-dimensional ZnIn_(2)S_(4)nanosheets on MnCo_(2)O_(4.5)nanorods to construct an ohmic-like type-I ZnIn_(2)S_(4)/MnCo_(2)O_(4.5)heterojunction for efficient photocatalytic hydrogen evolution.This ohmic-like charge transfer mechanism effectively addresses the intrinsic limitations inherent to conventional type-I heterojunctions neglecting IEF effects,particularly through IEF-induced enhancement of charge separation efficiency.Consequently,the optimized ZnIn_(2)S_(4)/MnCo_(2)O_(4.5)photocatalyst demonstrates an outstanding photocatalytic hydrogen evolution rate of 20.9 mmol g^(−1)h^(−1),14.9 times that of the bare ZnIn_(2)S_(4).Furthermore,the ohmic-like charge transport behavior has been rigorously validated by integrated advanced experimental characterizations,including in-situ X-ray photoelectron spectroscopy(XPS),Kelvin probe force microscopy(KPFM),and surface photovoltage(SPV)measurements,which collectively provide robust evidence for the proposed mechanism.This work offers valuable insights into the design of high-efficient ohmic-like type-I heterojunction catalysts for photocatalytic H_(2)evolution.展开更多
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2021D01A03)Key Research and Development Projects of Xinjiang Uygur Autonomous Region(2022B02038)+1 种基金Special Training Program for Scientific and Technological Talents of Ethnic Minorities in Xinjiang Uygur Autonomous Region(2020D03025)Project of Tian chi talent leader in Xinjiang Uygur Autonomous Region(2022).
文摘Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might take advantage of each compound and display an increased activity.In our previous study,boron doped-Cu_(3)NiBaTi_(4)O_(9)possessed a porous structure and its photocurrent response was apparent.To further verify its excellent catalytic activity,Al_(2)O_(3),and SiO_(2) were selected to replace with BaTi_(4)O_(9)to prepare different composites.The physical and chemical features of each sample were characterized with SEM,XRD,XPS,etc.to reveal their structural variations.Correspondingly,the H_(2)evolution rate was investigated with gas chromatography under the sunlight irritation.A distinct hydrogen yield was recorded with prepared samples.Further,the projected density of states analysis was taken through density functional theory calculations to appreciate the conduction band of the composite.The offered electrons during the photocatalytic process and the potential applicability of composites in the field of photocatalysis was verified.
文摘As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol synthesis,In_(2)O_(3)is an ideal catalyst and has garnered significant attention.Herein,cubic In_(2)O_(3)nanoparticles were prepared via the precipitation method and evaluated for CO_(2)hydrogenation to produce methanol.During the initial 10 h of reaction,CO_(2)conversion gradually increased,accompanied by a slow decrease of methanol selectivity,and the reaction reached equilibrium after 10-20 h on stream.This activation and induction stage may be attributed to the sintering of In_(2)O_(3)nanoparticles and the creation of more oxygen vacancies on In_(2)O_(3)surfaces.Further experimental studies demonstrate that hydrogen induction created additional oxygen vacancies during the catalyst activation stage,enhancing the performance of In_(2)O_(3)catalyst for CO_(2)hydrogenation.Density functional theory calculations and microkinetic simulations further demonstrated that surfaces with higher oxygen vacancy coverages or hydroxylated surfaces formed during this induction period can enhance the reaction rate and increase the CO_(2)conversion.However,they predominantly promote the formation of CO instead of methanol,leading to reduced methanol selectivity.These predictions align well with the above-mentioned experimental observations.Our work thus provides an in-depth analysis of the induction stage of the CO_(2)hydrogenation process on In_(2)O_(3)nano-catalyst,and offers valuable insights for significantly improving the CO_(2)reactivity of In_(2)O_(3)-based catalysts while maintaining long-term stability.
文摘Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.
基金support from the National Natural Science Foundation of China (51402100 and 21573066)the Provincial Natural Science Foundation of Hunan (2016JJ1006 and 2016TP1009)
文摘The electrochemical hydrogen evolution reaction（HER） on a non-precious electrocatalyst in an alkaline environment is of essential importance for future renewable energy. The design of advanced electrocatalysts for HER is the most important part to reduce the cost and to enhance the efficiency of water splitting. MoSis considered as one of the most promising electrocatalysts to replace the precious Pt catalyst.Herein, for the first time, we have successfully loaded MoSelectrocatalysts onto the CoOnanosheet array to catalyze HER with a low onset potential of6 mV. The high hydrogen evolution activity of MoSsupported on the CoOnanosheet array may be attributed to the increased active sites and the electronic interactions between MoSand CoO.
基金Project supported by the National Natural Science Foundation of China(51672067,51541208,51102074)the Natural Science Foundation of Hebei Province(E2018202034,E2015202070)+1 种基金the Foundation for Talent Training Project in Hebei Province(A2016002026)the Foundation for the Top Talents in Universities of Hebei Province(SLRC2017027)。
文摘Al_(2)O_(3)-Y_(2)O_(3)composite powder with TiO_(2)additive was plasma sprayed to prepare Al_(2)O_(3)-Y_(2)O_(3)composite coatings.The micro structure and properties evolution of the Al_(2)O_(3)-Y_(2)O_(3)coatings during high temperature and thermal shock resistance were investigated.The results show that the micro structure of the Al_(2)O_(3)-Y_(2)O_(3)-TiO_(2)coating is more uniform than that of the Al_(2)O_(3)-Y_(2)O_(3)coating.Meanwhile,amorphous phase is formed in the two coatings.The Al_(2)O_(3)-Y_(2)O_(3)(-TiO_(2))coatings were heat treated for 2 h at temperatures of 800,1000 and 1200℃,respectively.It is found that the microstructure and properties of the two coatings have no obvious change at 800℃.Some of the amorphous phase is crystallized at1000℃,and meanwhile Y_(2)O_(3)and Al_(2)O_(3)react to form YAG phase and YAM phase.At 1200℃,all of the amorphous phases are crystallized.After heat treatment,the micro hardness of the two coatings is increased.The thermal shock resistance of the Al_(2)O_(3)-Y_(2)O_(3)system coatings can be improved by using TC4 titanium alloy as substrate and with NiCrAlY bonding layer.Moreover,the Al_(2)O_(3)-Y_(2)O_(3)-TiO_(2)coating exhibits better thermal shock resistance due to the addition of TiO_(2).
基金financially supported by the National Natural Science Foundation of China(Grant No.51901011)the National Science and Technology Major Project(Grant Nos.2017-Ⅵ-0002-0072 and 2017-VII-0007-0100)+1 种基金the Fundamental Research Funds for Central Universities(Grant No.YWF-21-BJ-J-1034)the support from Youth Talent Support Program of Beihang University。
文摘(γ’+β)two-phase Ni-Al is a promising high-temperature protective coating material used on Ni-base superalloys since it has good interfacial compatibility with superalloys due to the low Al content compared to single-phaseβ-NiA l.In this paper,we aim to improve the oxidation resistance,whereby Ni-34Al-0.1Dy,a(γ’+β)two-phase Ni-Al alloy,was treated by laser shock processing(LSP)and the oxidation behavior at 1150℃ was investigated.The results showed that after oxidation,Al_(2)O_(3)scale formed on the originalβphase of the untreated alloy with a small grain size(200-800 nm),while for the LSP-treated samples,the scale grown on the originalβphase was dominantly composed of larger Al_(2)O_(3)grains with a size of 2-3μm.The distinction was attributed to the promotion ofθ-Al_(2)O_(3)toα-Al_(2)O_(3)transformation induced by the LSP,because the dislocation density,as well as surface roughness,were increased during LSP treatment which can provide heterogeneous nucleation sites forα-Al_(2)O_(3).In addition,the larger-size Al_(2)O_(3)particles,derived from the direct conversion of needle-likeθ-Al_(2)O_(3)in the initial oxidation stage,could rapidly overspread the wholeβphase surface thus reducing the scale growth rate.
基金funded by the National Natural Science Foundation of China(No.22002014)Applied Basic Research Program of Sichuan Province(No.2020YJ0068)+3 种基金“Young Talent Support Plan”of Xi'an Jiaotong UniversityNational Key Research and Development Program of China(No.2020YFC2005500)Key Research and Sichuan Province(No.2019YFS0514)Development Program of Science and Technology Department of financial support from the National Natural Science Foundation of China(No.22102152).
文摘The random movement and easy recombination of photoinduced charges lead to a low conversion efficiency for photocatalytic hydrogen evolution.The cocatalyst design is a promising route to address such problem through introducing an appropriate cocatalyst on the semiconductor photocatalysts to construct the high-efficiency heterojunctions.Herein,novel CoS/Nb_(2)O_(5) heterojunctions were constructed via in-situ loading CoS cocatalyst on the surface of Nb_(2)O_(5) nanosheets.Through the femtosecond-resolved transient absorption spectroscopy,the average lifetime of charge carriers for 10 wt% CoS/Nb_(2)O_(5)(159.6 ps)is drastically shortened by contrast with that of Nb_(2)O_(5)(5531.9 ps),strongly suggesting the rapid charge transfer from Nb_(2)O_(5) to CoS.The significantly improved charge-transfer capacity contributes to a high photocatalytic hydrogen evolution rate of 355µmol/h,up to 17.5 times compared with pristine Nb_(2)O_(5).This work would provide a new design platform in the construction of photocatalytic heterojunctions with high charge-transfer efficiency.
基金financially supported by the National Natural Science Foundation of China(Nos.51822706 and51777200)the Beijing Municipal and Technology Commission(No.Z181100000118006)。
文摘Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.
基金funded by the China Postdoctoral Science Foundation(pre-station,No.2019TQ0050)Applied Basic Research Program of Sichuan Province(No.2020YJ0068)+5 种基金the China Postdoctoral Science Foundation(No.2020M673186)National Natural Science Foundation of China(No.22002014)National Natural Science Foundation of China(No.11804248)the financial support from the National Natural Science Foundation of China(No.21971113)Natural Science Foundation of Tianjin(No.18JCQNJC03200)supported by MOE Tier 1 RG4/17 and MOE Tier 2 MOE2019-T2-2-105。
文摘Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer efficiency for photocatalysts.Herein,a new 2 D/2 D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core photocatalyst(DLWS/Nb_(2)O_(5))is designed.The atom-resolved HAADF-STEM results unravel the presence of an unusual 2 D/2 D shell/core interface in DLWS/Nb_(2)O_(5).Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra,the average lifetime of charge carriers for DLWS/Nb_(2)O_(5)(180.97 ps)is considerably shortened as compared to that of Nb_(2)O_(5)(230.50 ps),strongly indicating that the 2 D/2 D shell/core interface enables DLWS/Nb_(2)O_(5)to achieve ultrafast charge transfer from Nb_(2)O_(5)to atomic double-layer WS_(2),thus yielding a high photocatalytic H_(2)evolution rate of 237.6 mmol/h,up to10.8 times higher than that of pure Nb_(2)O_(5)nanosheet.This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.
基金support from the National Natural Science Foundation of China(51402100,21905088,21573066 and U19A2017)the Provincial Natural Science Foundation of Hunan(2020JJ5044,2022JJ10006)。
文摘Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.
基金supported by the Fundamental Research Funds for the Central Universities(DUT21LK34)Natural Science Foundation of Liaoning Province(2020-MS-113).
文摘Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.
基金support of the Fujian Science&Technol-ogy Innovation Laboratory for Optoelectronic Information of China(No.2021ZR124)the National Natural Science Foundation of China(No.21705150).
文摘Here,1D bis(N-carboxymethyl)peryleneimide(H_(2)PDI),0D 1,6,7,12-tetrachloro-bis(N-carboxymethyl)peryleneimide(4Cl-H_(2)PDI),and 2D 4Cl-H_(2)PDI/graphene quantum dot(4Cl-H_(2)PDI/GQD)nanostructures are synthesized and carefully analyzed.The effect of bay-/end-substitution and S-scheme heterojunction of PDI-based materials as main catalysts on the photocatalytic H_(2)O_(2)evolution is first studied through the oxygen reduction reaction(ORR).Under the visible-light irradiation(>420 nm),4Cl-H_(2)PDI and 4Cl-H_(2)PDI/GQD as photocatalysts exhibit the∼7 and∼16 times H_(2)O_(2)evolution rate than H_(2)PDI(1059.6 vs.2484.0 vs.160.0μM g^(−1) h^(−1)),respectively.The systematical experiments reveal that 4Cl-H_(2)PDI and 4Cl-H_(2)PDI/GQD should prefer a two-step single-electron ORR process,while H_(2)PDI may involve a 4e-water oxidation and one-step 2e-ORR process.Further experiments confirm that the bay-substitution and GQD doping of H_(2)PDI can promote the generation,transportation,and separation of photogenerated electrons and holes,and prolong the carrier lifetime.This work provides insight into PDI-based photocatalytic H_(2)O_(2)production.
文摘The oxygen evolution reaction(OER)serves as a fundamental half–reaction in the electrolysis of water for hydrogen production,which is restricted by the sluggish OER reaction kinetics and unable to be practically applied.The traditional lattice oxygen oxidation mechanism(LOM)offers an advantageous route by circumventing the formation of M-OOH^(*)in the adsorption evolution mechanism(AEM),thus enhancing the reaction kinetics of the OER but resulting in possible structural destabilization due to the decreased M–O bond order.Fortunately,the asymmetry of tetrahedral and octahedral sites in transition metal spinel oxides permits the existence of non-bonding oxygen,which could be activated by rational band structure design for direct O-O coupling,where the M–O bond maintains its initial bond order.Here,non-bonding oxygen was introduced into NiFe_(2)O_(4)via annealing in an oxygen-deficient atmosphere.Then,in-situ grown sulfate species on octahedral nickel sites significantly improved the reactivity of the non-bonding oxygen electrons,thereby facilitating the transformation of the redox center from metal to oxygen.LOM based on non-bonding oxygen(LOMNB)was successfully activated within NiFe_(2)O_(4),exhibiting a low overpotential of 206 mV to achieve a current density of 10 mA cm^(-2)and excellent durability of stable operation for over 150 h.Additionally,catalysts featuring varying band structures were synthesized for comparative analysis,and it was found that the reversible redox processes of non-bonding oxygen and the accumulation of non-bonding oxygen species containing 2p holes are critical prerequisites for triggering and sustaining the LOMNB pathway in transition metal spinel oxides.These findings may provide valuable insights for the future development of spinel-oxide-based LOM catalysts.
基金financial support from the“Lingyan”R&D Plan Project of Zhejiang Province(2025C02218)。
文摘The modulation of charge transfer pathways within type-I heterojunctions through interfacial electric field(IEF)engineering is of critical importance in promoting photocatalytic hydrogen evolution,effectively facilitating the separation of photogenerated charge carriers.In this study,we performed in-situ growth of two-dimensional ZnIn_(2)S_(4)nanosheets on MnCo_(2)O_(4.5)nanorods to construct an ohmic-like type-I ZnIn_(2)S_(4)/MnCo_(2)O_(4.5)heterojunction for efficient photocatalytic hydrogen evolution.This ohmic-like charge transfer mechanism effectively addresses the intrinsic limitations inherent to conventional type-I heterojunctions neglecting IEF effects,particularly through IEF-induced enhancement of charge separation efficiency.Consequently,the optimized ZnIn_(2)S_(4)/MnCo_(2)O_(4.5)photocatalyst demonstrates an outstanding photocatalytic hydrogen evolution rate of 20.9 mmol g^(−1)h^(−1),14.9 times that of the bare ZnIn_(2)S_(4).Furthermore,the ohmic-like charge transport behavior has been rigorously validated by integrated advanced experimental characterizations,including in-situ X-ray photoelectron spectroscopy(XPS),Kelvin probe force microscopy(KPFM),and surface photovoltage(SPV)measurements,which collectively provide robust evidence for the proposed mechanism.This work offers valuable insights into the design of high-efficient ohmic-like type-I heterojunction catalysts for photocatalytic H_(2)evolution.
