Composites derived from metal-organic frameworks(MOFs)show promise as catalysts for the photocat-alytic reduction of CO_(2).However,their potential is hindered by constraints such as limited light absorp-tion and slug...Composites derived from metal-organic frameworks(MOFs)show promise as catalysts for the photocat-alytic reduction of CO_(2).However,their potential is hindered by constraints such as limited light absorp-tion and sluggish electron transfer and separation,impacting the overall efficiency of the photocatalytic process.In this study,TiO_(2)nanocrystals,modified with Ptx+,underwent laser etching were encapsulated within the traditional MOF-ZIF-8 framework.This enhanced the adsorption capabilities for CO_(2)reactants and solar light,while also facilitating directed electron transfer and the separation of photogenerated charges.The finely-tuned catalyst demonstrates impressive CH_(4) selectivity at 9.5%,with yields of 250.24μmol g^(-1)h^(-1)for CO and 25.43μmol g^(-1)h^(-1)for CH_(4),utilizing water as a hole trap and H^(+)source.This study demonstrates the viability of achieving characteristics related to the separation of photogen-erated charges in TiO_(2)nanocrystals through laser etching and MOF composite catalysts.It offers novel perspectives for designing MOF-based catalysts with enhanced performance in artificial photosynthesis.展开更多
Photocatalytic CO_(2)reduction into value-added chemicals holds significant promise for carbon-neutral recycling and solar-to-fuel conversion.Enhancing reaction efficiency by manipulating charge transfer is a key appr...Photocatalytic CO_(2)reduction into value-added chemicals holds significant promise for carbon-neutral recycling and solar-to-fuel conversion.Enhancing reaction efficiency by manipulating charge transfer is a key approach to unlocking this potential.In this work,we construct a two-dimensional/twodimensional(2D/2D)FeSe_(2)/protonated carbon nitride(FeSe_(2)/PCN)heterostructure to promote the interfacial charge transfer dynamics,leading to a four-fold improved conversion efficiency of photocatalytic CO_(2)reduction with near 100%CO selectivity.Combining in situ X-ray photoelectron spectroscopy,in situ soft X-ray absorption spectroscopy,and femtosecond transient absorption spectroscopy,it is revealed that FeSe_(2)acts as an electron acceptor upon photoexcitation,introducing an additional electron transfer pathway from PCN to FeSe_(2)that suppresses radiative recombination and promotes charge transfer.In situ X-ray absorption fine structure spectroscopy,in situ diffuse reflectance infrared Fourier transform spectroscopy,and density functional theory calculation further unravel that the electron-enriched FeSe_(2)functions as the active sites for CO_(2)activation and significantly reduces the energy barrier of key intermediate COOH*formation,which is the rate-determined step for CO generation.This work underscores the importance of regulating photocarrier relaxation pathways to achieve effective spatial charge separation for promoted photocatalytic CO_(2)reduction and demonstrates the powerful functions of in situ spectroscopies in in-depth understanding of the photocatalytic mechanism.展开更多
The interface modulation significantly affects the photocatalytic performances of supported metal phthalocyanines(MPc)-based systems.Herein,ZnPc was loaded on nanosized Au-modified TiO_(2)nanosheets(Au-T)to obtain wid...The interface modulation significantly affects the photocatalytic performances of supported metal phthalocyanines(MPc)-based systems.Herein,ZnPc was loaded on nanosized Au-modified TiO_(2)nanosheets(Au-T)to obtain wide-spectrum ZnPc/Au-T photocatalysts.Compared with large Au NP(8 nm)-mediated ZnPc/Au-T photocatalyst,ultrasmall Au NP(3 nm)-mediated one shows advantageous photoactivity,achieving 3-and 10-fold CO_(2)conversion rates compared with reference ZnPc/T and pristine TiO_(2)nanosheets,respectively.Employing monochromatic beam-assisted surface photovoltage and photocurrent action,etc.,the introduction of ultrasmall Au NPs more effectively facilitates intrinsic interfacial charge transfer.Moreover,ZnP c molecules are found more dispersed with the existence of small Au NPs hence exposing abundant Zn^(2+)sites as the catalytic center for CO_(2)reduction.This work provides a feasible design strategy and renewed recognition for supported MPc-based photocatalyst systems.展开更多
The highly photocatalytic conversion of CO_(2)into valuable products is a promising method for mitigating the global greenhouse effect and increasing the energy supply.However,the utilization of electron-deficient act...The highly photocatalytic conversion of CO_(2)into valuable products is a promising method for mitigating the global greenhouse effect and increasing the energy supply.However,the utilization of electron-deficient active sites to activate CO_(2)leads to lower photocatalytic efficiency and selectivity.One effective strategy to improve CO_(2)photoreduction performance is making precise adjustments to the electronic structure of the photocatalyst.Herein,the defective TiO_(2)modified with Cu,Ba,and CuBa metal sites is synthesized via a simple photo-deposition method and applied for photoreduction of CO_(2).Among the prepared catalysts,Cu1Ba_(3)/TiO_(2)-SBO(TiO_(2)-SBO:TiO_(2)with surface and bulk oxygen vacancies)has been demonstrated to possess excellent photocatalytic conversion of CO_(2),with the activity levels of the CO and CH_(4) that are 8 and 6 times higher than the bare TiO_(2)-SBO,and the electron selectivity of CO is up to 53%.The results reveal that oxygen vacancies and CuBa bimetallic sites have a synergistic ability to facilitate the separation of photogenerated carriers.Furthermore,the electron-donor Ba metal enables modulation of the electronic structure of Cu co-catalysts,generating electron-rich Cu metal sites that accelerate the activation of CO_(2).Meanwhile,the theoretical calculations prove that the Cu1Ba_(3)/TiO_(2)-SBO has the stronger CO_(2)adsorption energy,and its strengthened binding of^(*)COOH and the markedly reduced formation energy of CO and^(*)CO intermediates boost the conversion of COOH to CO and enhance the selectivity of CO.Thereby,the defective TiO_(2)modified with CuBa bimetal represents a more effective measure for CO_(2)reduction into valuable products.展开更多
Herein,PtO-supported GdFeO_(3)(PtO/GdFeO_(3))composite photocatalysts were synthesized by a solutionbased technique.Extensive analysis using various analytical instruments has shown that PtO plays a crucial function i...Herein,PtO-supported GdFeO_(3)(PtO/GdFeO_(3))composite photocatalysts were synthesized by a solutionbased technique.Extensive analysis using various analytical instruments has shown that PtO plays a crucial function in augmenting the visible light absorption capacity of composites.Better photogenerated charge carrier transport was credited with this improvement,which led to a decrease in bandgap energy as low as 2.14 eV.The PtO/GdFeO_(3) nanocomposites showed remarkable photocatalytic activity when exposed to visible light,especially in the conversion of CO_(2) into CH_(3)OH.After 9 h of light,a noteworthy yield of 1550μmol·g^(−1) of methanol was produced,demonstrating maximum efficiency at a dose of 2.0 g·L^(−1) and a concentration of 5.0%PtO/GdFeO_(3).This yield indicates the effectiveness of the heterostructure,which outperformed pristine GdFeO_(3) by a factor of 7.85.This significant enhancement highlights the potential advantages of the modified structure in improving performance.Most significantly,the photocatalyst's durability maintained 98.0%of its initial efficacy throughout five cycles.The success of PtO/GdFeO_(3) is largely due to the synergistic light absorption capabilities and enhanced photocharge carrier separation that the integration of PtO produced.It highlights the conversion of CO_(2) into valuable chemicals under visible light exposure,as well as the promise of mixed oxide nanostructures in ecologically responsible material creation.展开更多
Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrins...Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrinsic electronic structure with d-orbitals fully filled, thus limiting the activation and reduction of CO_(2). To address this issue and maximize the photoreduction of CO_(2), herein we have designed Au@CZS@MO-400 triple-shelled hollow nanospheres by depositing Cd_(0.7)Zn_(0.3)S (CZS) on the outer surface of the MO-400 (MnO_(2) annealed at 400 ℃) hollow nanospheres and then Au nanoparticles on the CZS surface. It is manifested that the resultant 3%Au@CZS@MO-400 achieves a remarkably boosted photoreduction of CO_(2) with the CO/CH_(4) yield rates as high as 68.25/12.42 µmol g^(-1) h^(-1), increased by 3.7/1.5 times over MO-400 and 12.9/1.5 times over CZS. The combined analyses from X-ray photoelectron spectroscopy and density functional theory calculations confirm the creation of electron-deficient Auδ+ active sites by modulating their electron configuration by CZS, consequently decreasing the CO_(2)-Au antibonding-orbital occupancy to reinforce the adsorption strength of CO_(2) onto the Au active sites and in turn boost the photoreduction of CO_(2). Moreover, it is demonstrated that the Au@CZS@MO-400 hollow nanospheres are quite efficient for supplying the Au cocatalyst with photoelectrons for CO_(2) reduction reactions due to the good energy band matching, unique hollow structure and high electron spin polarization of MO-400. This work provides important guidance for understanding and modifying photocatalysts to maximize their photoreduction of CO_(2).展开更多
The conversion of solar energy to facilitate the photocatalytic transformation of CO_(2)into CH4 addresses the energy shortage caused by reducing humans’excessive dependence on fossil fuels and contributes substantia...The conversion of solar energy to facilitate the photocatalytic transformation of CO_(2)into CH4 addresses the energy shortage caused by reducing humans’excessive dependence on fossil fuels and contributes substantially to the goal of carbon neu-trality.However,there are still many limitations on the conversion of CO_(2)to CH_(4).In this work,a series of ZrO_(2)/Bi_(19)S_(27)Br_(3)composite photocatalysts was prepared by the solvothermal method and applied to the methanation reaction of CO_(2).Combin-ing Bi_(19)S_(27)Br_(3)with ZrO_(2)forms a heterojunction with a strong coupling interface.This greatly enhanced the CO_(2)adsorption performance of the 50-ZrO_(2)/Bi_(19)S_(27)Br_(3)composite and promoted the effective separation of photogenerated electron–hole pairs.Without the addition of photosensitizers,the CH_(4)selectivity of the 50-ZrO_(2)/Bi_(19)S_(27)Br_(3)composite is approximately 63%,and the CH_(4)generation rate is 18.04μmol/(gcat·h),which is noticeably higher than that of ZrO_(2)or Bi_(19)S_(27)Br_(3).This research demonstrated enhanced photocatalytic CO_(2)reduction efficiency using Bi_(19)S_(27)Br_(3)-based materials,providing a novel approach for the use of CO_(2)resources.展开更多
The stems of water convolvulus were employed as biotemplates for the replication of their optimized 3D hierarchical architecture to synthesize porous MgO-modified TiO2 . The photocatalytic reduction of CO2 with H2O va...The stems of water convolvulus were employed as biotemplates for the replication of their optimized 3D hierarchical architecture to synthesize porous MgO-modified TiO2 . The photocatalytic reduction of CO2 with H2O vapor into hydrocarbon fuel was studied with these MgO-TiO2 nanostructures as the photocatalysts with the benefits of improved CO2 adsorption and activation through incorporated MgO. Various factors involving CO2 adsorption capacity, migration of charge carriers to the surface, and the number of activity sites, which depend on the amount of added MgO, determine the photocatalytic conversion efficiency.展开更多
A series of highly dispersed platinum‐deposited porous g‐C3N4 (Pt/pg‐C3N4) were successfully fabricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g‐C3N4 as precursors. Porou...A series of highly dispersed platinum‐deposited porous g‐C3N4 (Pt/pg‐C3N4) were successfully fabricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g‐C3N4 as precursors. Porous g‐C3N4 was fabricated by a pretreatment strategy using melamine as a raw material.The morphology, porosity, phase, chemical structure, and optical and electronic properties ofas‐prepared Pt/pg‐C3N4 were characterized. The photocatalytic activity of as‐prepared Pt/pg‐C3N4was preliminarily evaluated by the degradation of aqueous azo dyes methyl orange under visible light irradiation. The as‐prepared Pt/pg‐C3N4 were further applied to the degradation and mineralization of aqueous 4‐fluorophenol. The recyclability of Pt/pg‐C3N4 was evaluated under four consecutive photocatalytic runs.展开更多
Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high...Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high energy barrier for CO_(2) photoreduction on the surface of photocatalysts com‐promise the catalytic performance.Herein,a 2D/2D Bi_(2)MoO_(6)/BiOI composite was fabricated to achieve improved CO_(2) photoreduction efficiency.Charge transfer in the composite was facilitated by the van der Waals heterojunction with a large‐area interface.Work function calculation demon‐strated that S‐scheme charge transfer is operative in the composite,and effective charge separation and strong redox capability were revealed by time‐resolved photoluminescence and electron para‐magnetic resonance spectroscopy.Moreover,the intermediates of CO_(2) photoreduction were identi‐fied based on the in situ diffuse reflectance infrared Fourier‐transform spectra.Density functional theory calculations showed that CO_(2) hydrogenation is the rate‐determining step for yielding CH_(4) and CO.Introducing Bi_(2)MoO_(6) into the composite further decreased the energy barrier for CO_(2) photoreduction on BiOI by 0.35 eV.This study verifies the synergistic effect of the S‐scheme heterojunction and van der Waals heterojunction in the 2D/2D composite.展开更多
The photoreduction of CO_(2)to achieve high-value-added hydrocarbons under simulated sunlight irradiation is advantageous,but challenging.In this study,a series of MgO and Au nanoparticle-co-modified g-C_(3)N_(4)photo...The photoreduction of CO_(2)to achieve high-value-added hydrocarbons under simulated sunlight irradiation is advantageous,but challenging.In this study,a series of MgO and Au nanoparticle-co-modified g-C_(3)N_(4)photocatalysts were synthesized and subsequently applied for the photocatalytic reduction of CO_(2)with H2O under simulated solar irradiation.The best photocatalytic performance was demonstrated by the Au and 3%MgO-co-modified g-C_(3)N_(4)photocatalysts with CO,CH_(4),CH3OH,and CH3CHO yields of 423.9,83.2,47.2,and 130.4μmol/g,respectively,in a 3-h reaction.We investigated the effects of MgO and Au as cocatalysts on photocatalytic behaviors,respectively.The characterizations and experimental results showed that the enhanced photocatalytic activity was due to the synergistic effect among the components of the ternary photocatalyst.The cocatalyst MgO can activate CO_(2)(adsorbed at the interface between the MgO and Au particles),and the Mg-N bonds formed in the MgO-CN nanosheets played an important role in the charge transfer.Meanwhile,the Au particles that were modified into MgO/g-C_(3)N_(4)can increase the absorption of visible light via the surface plasmon resonance effect and further reduce the activation energies of the photoreduction of CO_(2)using H2O.This study provided an effective method for the modification of traditional primary photocatalysts with promising performance for photocatalytic CO_(2)reduction.展开更多
Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to n...Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to navigate the photocatalytic CO_(2) reduction reaction(CRR).Herein,we elucidate the behaviors of isotype heterojunctions toward photocatalytic CRR over a representative photocatalyst,g-C_(3)N_(4).Impressively,the isotype heterojunctions possess a significantly higher efficiency for the spatial separation and transfer of photogenerated carriers than the single components.Along with the intrinsically outstanding stability,the isotype heterojunctions exhibit an exceptional and stable activity toward the CO_(2) photoreduction to CO.More importantly,by combining quantitative in situ technique with the first-principles modeling,we elucidate that the enhanced photoinduced charge dynamics promotes the production of key intermediates and thus the whole reaction kinetics.展开更多
Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects...Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects of different concentrations of living/dead algae species,including Aphanizomenon flosaquae (AF) and Microcystis aeruginosa (MA),on the photoreduction rate of Hg2+ under various light conditions.The experimental results showed that percentage reduction of Hg2+ was significantly influenced by radiation wavelengths,and dramatically decreased with the presence of algae.The highest percentage reduction of Hg2+ was induced by UV-A,followed by UV-B,visible light and dark for both living and dead AF,and the order was dark > UV-A > UV-B > visible light for both living and dead MA.There were two aspects,i.e.,energy and attenuation rate of light radiation and excrementitious generated from algae metabolisms,were involved in the processes of Hg2+ photoreduction with the presence of algae under different light conditions.The percentage reduction of Hg2+ decreased from 15% to 11% when living and dead AF concentrations increased by 10 times (from 106 to 105 cells/mL),and decreased from11% to ~9% in the case of living and dead MA increased.Algae can adsorb Hg2+ and decrease the concentration of free Hg2+,thus inhibiting Hg2+ photoreduction,especially under the conditions with high concentrations of algae.No significant differences were found in percentage reduction of Hg2+ between living and dead treatments of algae species.The results are of great importance for understanding the role of algae in Hg2+ photoreduction.展开更多
The BiOCl(BOC)synthesized by the water bath heating method was treated with sodium borohydride(NaBH_(4))to introduce oxygen vacancies(OVs).At the same time,Au nanoparticles were loaded to prepare a series of Au/BiOCl ...The BiOCl(BOC)synthesized by the water bath heating method was treated with sodium borohydride(NaBH_(4))to introduce oxygen vacancies(OVs).At the same time,Au nanoparticles were loaded to prepare a series of Au/BiOCl samples with different ratios.OVs and Au nanoparticles can promote the light absorption of host photocatalyst in the visible region.The calculated work function of BiOCl and Au can verify the existence of Ohmic contact between the interface of them,which is conducive to the separation of charge carriers.Through a series of photoelectric tests,it was verified experimentally that the separation of charge carriers is indeed enhanced.The high-energy hot electrons produced by Au under the surface plasmon resonance(SPR)effect can increase the counts of electrons to participate in the CO_(2)reduction reaction.Especially for 1.0%-Au/BOC,the yields of CO can reach 43.16μmol g^(−1)h^(−1),which is 6.6 times more than that of BOC.Therefore,loading precious metal on semiconductors is an effective strategy to promote the photocatalytic performance of CO_(2)reduction reactions.展开更多
Efficiently converting CO_(2)and H_(2)O into value-added chemicals using solar energy is a viable approach to address global warming and the energy crisis.However,achieving artificial photocatalytic CO_(2)reduction us...Efficiently converting CO_(2)and H_(2)O into value-added chemicals using solar energy is a viable approach to address global warming and the energy crisis.However,achieving artificial photocatalytic CO_(2)reduction using H_(2)O as the reductant poses challenges is due to the difficulty in efficient cooperation among multiple functional moieties.Metal-organic frameworks(MOFs)are promising candidates for overall CO_(2)photoreduction due to their large surface area,diverse active sites,and excellent tailorability.In this study,we designed a metal-organic framework photocatalyst,named PCN-224(Zn)-Bpy(Ru),by integrating photoactive Zn(Ⅱ)-porphyrin and Ru(Ⅱ)-bipyridyl moieties.In comparison,two isostructural MOFs just with either Zn(Ⅱ)-porphyrin or Ru(Ⅱ)-bipyridyl moiety,namely PCN-224-Bpy(Ru)and PCN-224(Zn)-Bpy were also synthesized.As a result,PCN-224(Zn)-Bpy(Ru)exhibited the highest photocatalytic conversion rate of CO_(2)to CO,with a production rate of 7.6μmol·g^(-1)·h^(-1)in a mixed solvent of CH_(3)CN and H_(2)O,without the need for co-catalysts,photosensitizers,or sacrificial agents.Mass spectrometer analysis detected the signals of^(13)CO(m/z=29),^(13)C^(18)O(m/z=31),^(16)O^(18)O(m/z=34),and^(18)O_(2)(m/z=36),confirming that CO_(2)and H_(2)O acted as the carbon and oxygen sources for CO and O_(2),respectively,thereby confirming the coupling of photocatalytic CO_(2)reduction with H_(2)O oxidation.In contrast,using PCN-224-Bpy(Ru)or PCN-224(Zn)-Bpy as catalysts under the same conditions resulted in significantly lower CO production rates of only 1.5 and 0μmol·g^(-1)·h^(-1),respectively.Mechanistic studies revealed that the lowest unoccupied molecular orbital(LUMO)potential of PCN-224(Zn)-Bpy(Ru)is more negative than the redox potentials of CO_(2)/CO,and the highest occupied molecular orbital(HOMO)potential is more positive than that of H_(2)O/O_(2),satisfying the thermodynamic requirements for overall photocatalytic CO_(2)reduction.In comparison,the HOMO potential of PCN-224(Zn)-Bpy without Ru(II)-bipyridyl moieties is less positive than that of H_(2)O/O_(2),indicating that the Ru(II)-bipyridyl moiety is thermodynamically necessary for CO_(2)reduction coupled with H_(2)O oxidation.Additionally,photoluminescence spectroscopy revealed that the fluorescence of PCN-224(Zn)-Bpy(Ru)was almost completely quenched,and a longer average photoluminescence lifetime compared to PCN-224(Zn)-Bpy and PCN-224-Bpy(Ru)was observed.These suggest a low recombination rate of photogenerated carriers in PCN-224(Zn)-Bpy(Ru),which also supported by the higher photocurrent observed in PCN-224(Zn)-Bpy(Ru)compared to PCN-224(Zn)-Bpy and PCN-224-Bpy(Ru).In summary,the integrated Zn(II)-porphyrin and Ru(II)-bipyridyl moieties in PCN-224(Zn)-Bpy(Ru)play important roles of a photosensitizer and CO_(2)reduction as well as H_(2)O oxidation sites,and their efficient cooperation optimizes the band structure,thereby facilitating the coupling of CO_(2)reduction with H_(2)O oxidation and resulting in highperformance artificial photocatalytic CO_(2)reduction.展开更多
The performance of CeO2-TiO2 photocatalyst for the photocatalytic reduction of CO2 into methanol was studied under visible light irradiation. The as-prepared catalysts were characterized for their structural, textural...The performance of CeO2-TiO2 photocatalyst for the photocatalytic reduction of CO2 into methanol was studied under visible light irradiation. The as-prepared catalysts were characterized for their structural, textural and optical properties using X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, X-ray photoelectron spectroscopy（XPS）, nitrogen physisorption analysis, UV-vis spectroscopy and photoluminescence（PL） spectroscopy. The characterization results indicated that the presence of CeO2 stabilized the anatase phase of TiO2, decreased its crystallite size, increased the surface area, reduced the band gap energy and lowered the rate of electron-hole pair recombination. The CeO2-TiO2 photocatalyst showed an increased methanol yield of 18.6 μmol/g under visible light irradiation, compared to the bare TiO2（6.0 μmol/g）.展开更多
Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with hi...Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride（Cl-） concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg（0） in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0–10 μg/g Cl-, and irradiated with 3.52–5.78 W·m-2 UV（280–400 nm）radiation in a Luz Chem photoreactor. Photoreduction rate constants（k）（0.14–0.59 hr-1） had positive linear relationships with [Cl-], while photoreduced Hg amounts（Hg（Ⅱ）red） had negative linear relationships with [Cl-]（1287–64 pg in 200 g melted snow）. Varying UV and[Cl-] both altered Hg（Ⅱ）red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading,our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow（smaller Hg（Ⅱ）red expected）, but the Hg in the melted snow that is photoreduced may do so more quickly（larger k expected）.展开更多
Uranium removal from aqueous solutions using environmentally friendly photocatalytic technology is a novel approach for resource recovery.Herein,carbon nitride/activated carbon composite materials(CN/AC)were investiga...Uranium removal from aqueous solutions using environmentally friendly photocatalytic technology is a novel approach for resource recovery.Herein,carbon nitride/activated carbon composite materials(CN/AC)were investigated for U(Ⅵ)reduction under visible light.An exceptional boost in photocatalytic activity was observed for CN/AC composites(up to 70 times over the conventional bulk g-C_(3)N_(4)).The strong interactive conjugatedπ-bond structure between g-C_(3)N_(4) and AC accelerated the migration of carriers and then prolonged the electron lifetime.CN/AC composites exhibited excellent compatibility with different water substrates and were resilience to a wide range of p H changes and abundant competitive anions/cations.Quenching experiments and electron microscopy characterization indicated that U(VI)was reduced by photogenerated electrons and deposited on the edge of CN/AC composites.The low-cost,high-performance carbon-based composite material proposed in this work is a potential candidate for the efficient treatment of radioactive wastewater.展开更多
COphotoreduction is an attractive process which allows the storage of solar energy and synthesis of solar fuels. Many different photocatalytic systems have been developed, while the alternative photo-reactors are stil...COphotoreduction is an attractive process which allows the storage of solar energy and synthesis of solar fuels. Many different photocatalytic systems have been developed, while the alternative photo-reactors are still insufficiently investigated. In this work, photoreduction of COwith HO into CHwas investigated in a modified concentrating solar reactor, using TiOand Pt/TiOas the catalysts. The TiOand Pt/TiOsamples were extensively characterized by different techniques including powder X-ray diffraction（XRD）, Nadsorption/desorption and UV–vis absorption. The catalytic performance of the TiOand Pt/TiOsamples in the gas phase was evaluated under unconcentrated and concentrated Xe-lamp light and nature solar light with different concentrating ratios. Various parameters of the reaction system and the catalysts were investigated and optimized to maximize the catalytic performance of COreduction system. Compared with the normal light irradiation, the TiOand Pt/TiOsamples show higher photocatalytic activity（about 6–7 times） for reducing COinto CHunder concentrated Xe-lamp light and nature solar light. In the range of experimental light intensity, it is found that the concentration of the light makes it suitable for the catalytic reaction, and increases the utilization efficiency of the TiOand Pt/TiOsamples while does not decrease the quantum efficiency.展开更多
Retaining the ultrathin structure of two-dimensional materials is very important for stabilizing their catalytic performances.However,aggregation and restacking are unavoidable,to some extent,due to the van der Waals ...Retaining the ultrathin structure of two-dimensional materials is very important for stabilizing their catalytic performances.However,aggregation and restacking are unavoidable,to some extent,due to the van der Waals interlayer interaction of two-dimensional materials.Here,we address this challenge by preparing an origami accordion structure of ultrathin twodimensional graphitized carbon nitride(oa-C_(3)N_(4))with rich vacancies.This novel structured oa-C_(3)N_(4) shows exceptional photocatalytic activity for the CO_(2) reduction reaction,which is 8.1 times that of the pristine C_(3)N_(4).The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects,which leads to modification of the electronic structure,regulation of the CO_(2) adsorption energy,and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction.This study provides a new avenue for the development of stable highperformance two-dimensional catalytic materials.展开更多
文摘Composites derived from metal-organic frameworks(MOFs)show promise as catalysts for the photocat-alytic reduction of CO_(2).However,their potential is hindered by constraints such as limited light absorp-tion and sluggish electron transfer and separation,impacting the overall efficiency of the photocatalytic process.In this study,TiO_(2)nanocrystals,modified with Ptx+,underwent laser etching were encapsulated within the traditional MOF-ZIF-8 framework.This enhanced the adsorption capabilities for CO_(2)reactants and solar light,while also facilitating directed electron transfer and the separation of photogenerated charges.The finely-tuned catalyst demonstrates impressive CH_(4) selectivity at 9.5%,with yields of 250.24μmol g^(-1)h^(-1)for CO and 25.43μmol g^(-1)h^(-1)for CH_(4),utilizing water as a hole trap and H^(+)source.This study demonstrates the viability of achieving characteristics related to the separation of photogen-erated charges in TiO_(2)nanocrystals through laser etching and MOF composite catalysts.It offers novel perspectives for designing MOF-based catalysts with enhanced performance in artificial photosynthesis.
基金supported by the National Natural Science Foundation of China(12241502,92045301)Fundamental Research Funds for the Central Universities(20720220010)+7 种基金USTC Research Funds of the Double First-Class Initiative(YD2310002012)the Launching Special Funds of Scientific Research for Introduced Talents from University of Science and Technology of China(KY2310000060)National Key Research and Development Program of China(2019YFA0405602)Anhui Provincial Natural Science Foundation(2408085QB049)the Instruments Center for Physical Science and USTC Center for Micro and Nanoscale Research and Fabrication,University of Science and Technology of Chinathe solid supports from the BL03U,BL10B,and BL12B beamlines of the National Synchrotron Radiation Laboratory(NSRL,Hefei)the Shanghai Synchrotron Radiation Facility(SSRF,Shanghai)of BL11B(https://cstr.cn/31124.02.SSRF.BL11B)and BL14W1(https://cstr.cn/31124.02.SSRF.BL14W1)beamlines for the assistance on XAFS measurementsAnhui Chuangpu Instruments Co.,Ltd.for the assistance in the test of Table XAFS。
文摘Photocatalytic CO_(2)reduction into value-added chemicals holds significant promise for carbon-neutral recycling and solar-to-fuel conversion.Enhancing reaction efficiency by manipulating charge transfer is a key approach to unlocking this potential.In this work,we construct a two-dimensional/twodimensional(2D/2D)FeSe_(2)/protonated carbon nitride(FeSe_(2)/PCN)heterostructure to promote the interfacial charge transfer dynamics,leading to a four-fold improved conversion efficiency of photocatalytic CO_(2)reduction with near 100%CO selectivity.Combining in situ X-ray photoelectron spectroscopy,in situ soft X-ray absorption spectroscopy,and femtosecond transient absorption spectroscopy,it is revealed that FeSe_(2)acts as an electron acceptor upon photoexcitation,introducing an additional electron transfer pathway from PCN to FeSe_(2)that suppresses radiative recombination and promotes charge transfer.In situ X-ray absorption fine structure spectroscopy,in situ diffuse reflectance infrared Fourier transform spectroscopy,and density functional theory calculation further unravel that the electron-enriched FeSe_(2)functions as the active sites for CO_(2)activation and significantly reduces the energy barrier of key intermediate COOH*formation,which is the rate-determined step for CO generation.This work underscores the importance of regulating photocarrier relaxation pathways to achieve effective spatial charge separation for promoted photocatalytic CO_(2)reduction and demonstrates the powerful functions of in situ spectroscopies in in-depth understanding of the photocatalytic mechanism.
基金supported by the National Natural Science Foundation of China(Nos.U2102211 and 22378101)the Fundamental Research Foundation for Universities of Heilongjiang Province(No.2021-KYYWF-0004)the Science Fund for Distinguished Young Scholars of Heilongjiang University(No.JCL202102)。
文摘The interface modulation significantly affects the photocatalytic performances of supported metal phthalocyanines(MPc)-based systems.Herein,ZnPc was loaded on nanosized Au-modified TiO_(2)nanosheets(Au-T)to obtain wide-spectrum ZnPc/Au-T photocatalysts.Compared with large Au NP(8 nm)-mediated ZnPc/Au-T photocatalyst,ultrasmall Au NP(3 nm)-mediated one shows advantageous photoactivity,achieving 3-and 10-fold CO_(2)conversion rates compared with reference ZnPc/T and pristine TiO_(2)nanosheets,respectively.Employing monochromatic beam-assisted surface photovoltage and photocurrent action,etc.,the introduction of ultrasmall Au NPs more effectively facilitates intrinsic interfacial charge transfer.Moreover,ZnP c molecules are found more dispersed with the existence of small Au NPs hence exposing abundant Zn^(2+)sites as the catalytic center for CO_(2)reduction.This work provides a feasible design strategy and renewed recognition for supported MPc-based photocatalyst systems.
文摘The highly photocatalytic conversion of CO_(2)into valuable products is a promising method for mitigating the global greenhouse effect and increasing the energy supply.However,the utilization of electron-deficient active sites to activate CO_(2)leads to lower photocatalytic efficiency and selectivity.One effective strategy to improve CO_(2)photoreduction performance is making precise adjustments to the electronic structure of the photocatalyst.Herein,the defective TiO_(2)modified with Cu,Ba,and CuBa metal sites is synthesized via a simple photo-deposition method and applied for photoreduction of CO_(2).Among the prepared catalysts,Cu1Ba_(3)/TiO_(2)-SBO(TiO_(2)-SBO:TiO_(2)with surface and bulk oxygen vacancies)has been demonstrated to possess excellent photocatalytic conversion of CO_(2),with the activity levels of the CO and CH_(4) that are 8 and 6 times higher than the bare TiO_(2)-SBO,and the electron selectivity of CO is up to 53%.The results reveal that oxygen vacancies and CuBa bimetallic sites have a synergistic ability to facilitate the separation of photogenerated carriers.Furthermore,the electron-donor Ba metal enables modulation of the electronic structure of Cu co-catalysts,generating electron-rich Cu metal sites that accelerate the activation of CO_(2).Meanwhile,the theoretical calculations prove that the Cu1Ba_(3)/TiO_(2)-SBO has the stronger CO_(2)adsorption energy,and its strengthened binding of^(*)COOH and the markedly reduced formation energy of CO and^(*)CO intermediates boost the conversion of COOH to CO and enhance the selectivity of CO.Thereby,the defective TiO_(2)modified with CuBa bimetal represents a more effective measure for CO_(2)reduction into valuable products.
基金support from National Natural Science Foundation of China(21771047)Natural Science Foundation of Heilongjiang Province,China(YQ2020E029)Open Project of State Key Laboratory of Inorganic Synthesis&Preparative Chemistry,Jilin University(2023-17).
文摘Herein,PtO-supported GdFeO_(3)(PtO/GdFeO_(3))composite photocatalysts were synthesized by a solutionbased technique.Extensive analysis using various analytical instruments has shown that PtO plays a crucial function in augmenting the visible light absorption capacity of composites.Better photogenerated charge carrier transport was credited with this improvement,which led to a decrease in bandgap energy as low as 2.14 eV.The PtO/GdFeO_(3) nanocomposites showed remarkable photocatalytic activity when exposed to visible light,especially in the conversion of CO_(2) into CH_(3)OH.After 9 h of light,a noteworthy yield of 1550μmol·g^(−1) of methanol was produced,demonstrating maximum efficiency at a dose of 2.0 g·L^(−1) and a concentration of 5.0%PtO/GdFeO_(3).This yield indicates the effectiveness of the heterostructure,which outperformed pristine GdFeO_(3) by a factor of 7.85.This significant enhancement highlights the potential advantages of the modified structure in improving performance.Most significantly,the photocatalyst's durability maintained 98.0%of its initial efficacy throughout five cycles.The success of PtO/GdFeO_(3) is largely due to the synergistic light absorption capabilities and enhanced photocharge carrier separation that the integration of PtO produced.It highlights the conversion of CO_(2) into valuable chemicals under visible light exposure,as well as the promise of mixed oxide nanostructures in ecologically responsible material creation.
基金supported by the Gansu Province Outstanding PhD Student Fund(No.24JRRA206)the National Natural Sci-ence Foundation of China(No.52162040).
文摘Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrinsic electronic structure with d-orbitals fully filled, thus limiting the activation and reduction of CO_(2). To address this issue and maximize the photoreduction of CO_(2), herein we have designed Au@CZS@MO-400 triple-shelled hollow nanospheres by depositing Cd_(0.7)Zn_(0.3)S (CZS) on the outer surface of the MO-400 (MnO_(2) annealed at 400 ℃) hollow nanospheres and then Au nanoparticles on the CZS surface. It is manifested that the resultant 3%Au@CZS@MO-400 achieves a remarkably boosted photoreduction of CO_(2) with the CO/CH_(4) yield rates as high as 68.25/12.42 µmol g^(-1) h^(-1), increased by 3.7/1.5 times over MO-400 and 12.9/1.5 times over CZS. The combined analyses from X-ray photoelectron spectroscopy and density functional theory calculations confirm the creation of electron-deficient Auδ+ active sites by modulating their electron configuration by CZS, consequently decreasing the CO_(2)-Au antibonding-orbital occupancy to reinforce the adsorption strength of CO_(2) onto the Au active sites and in turn boost the photoreduction of CO_(2). Moreover, it is demonstrated that the Au@CZS@MO-400 hollow nanospheres are quite efficient for supplying the Au cocatalyst with photoelectrons for CO_(2) reduction reactions due to the good energy band matching, unique hollow structure and high electron spin polarization of MO-400. This work provides important guidance for understanding and modifying photocatalysts to maximize their photoreduction of CO_(2).
基金supported by the National Natural Science Foundation of China(Nos.22378172,22138011,22378206).
文摘The conversion of solar energy to facilitate the photocatalytic transformation of CO_(2)into CH4 addresses the energy shortage caused by reducing humans’excessive dependence on fossil fuels and contributes substantially to the goal of carbon neu-trality.However,there are still many limitations on the conversion of CO_(2)to CH_(4).In this work,a series of ZrO_(2)/Bi_(19)S_(27)Br_(3)composite photocatalysts was prepared by the solvothermal method and applied to the methanation reaction of CO_(2).Combin-ing Bi_(19)S_(27)Br_(3)with ZrO_(2)forms a heterojunction with a strong coupling interface.This greatly enhanced the CO_(2)adsorption performance of the 50-ZrO_(2)/Bi_(19)S_(27)Br_(3)composite and promoted the effective separation of photogenerated electron–hole pairs.Without the addition of photosensitizers,the CH_(4)selectivity of the 50-ZrO_(2)/Bi_(19)S_(27)Br_(3)composite is approximately 63%,and the CH_(4)generation rate is 18.04μmol/(gcat·h),which is noticeably higher than that of ZrO_(2)or Bi_(19)S_(27)Br_(3).This research demonstrated enhanced photocatalytic CO_(2)reduction efficiency using Bi_(19)S_(27)Br_(3)-based materials,providing a novel approach for the use of CO_(2)resources.
基金supported by the National Basic Research Program of China(973 Program,2014CB239302,2013CB632404)the Natural Science Foundation of Jiangsu Province(BK20130053)the National Natural Science Foundation of China(51272101,51202005,21473091)
文摘The stems of water convolvulus were employed as biotemplates for the replication of their optimized 3D hierarchical architecture to synthesize porous MgO-modified TiO2 . The photocatalytic reduction of CO2 with H2O vapor into hydrocarbon fuel was studied with these MgO-TiO2 nanostructures as the photocatalysts with the benefits of improved CO2 adsorption and activation through incorporated MgO. Various factors involving CO2 adsorption capacity, migration of charge carriers to the surface, and the number of activity sites, which depend on the amount of added MgO, determine the photocatalytic conversion efficiency.
基金supported by the National Natural Science Foundation of China (51568049, 51208248, 51468043, 21366024)the National Science Fund for Excellent Young Scholars (51422807)+1 种基金the Natural Science Foundation of Jiangxi Province, China (20161BAB206118, 20114BAB213015)the Natural Science Foundation of Jiangxi Provincial Department of Education, China (GJJ14515, GJJ12456)~~
文摘A series of highly dispersed platinum‐deposited porous g‐C3N4 (Pt/pg‐C3N4) were successfully fabricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g‐C3N4 as precursors. Porous g‐C3N4 was fabricated by a pretreatment strategy using melamine as a raw material.The morphology, porosity, phase, chemical structure, and optical and electronic properties ofas‐prepared Pt/pg‐C3N4 were characterized. The photocatalytic activity of as‐prepared Pt/pg‐C3N4was preliminarily evaluated by the degradation of aqueous azo dyes methyl orange under visible light irradiation. The as‐prepared Pt/pg‐C3N4 were further applied to the degradation and mineralization of aqueous 4‐fluorophenol. The recyclability of Pt/pg‐C3N4 was evaluated under four consecutive photocatalytic runs.
文摘Reducing CO_(2) to hydrocarbon fuels by solar irradiation provides a feasible channel for mitigating excessive CO_(2) emissions and addressing resource depletion.Nevertheless,severe charge recombi‐nation and the high energy barrier for CO_(2) photoreduction on the surface of photocatalysts com‐promise the catalytic performance.Herein,a 2D/2D Bi_(2)MoO_(6)/BiOI composite was fabricated to achieve improved CO_(2) photoreduction efficiency.Charge transfer in the composite was facilitated by the van der Waals heterojunction with a large‐area interface.Work function calculation demon‐strated that S‐scheme charge transfer is operative in the composite,and effective charge separation and strong redox capability were revealed by time‐resolved photoluminescence and electron para‐magnetic resonance spectroscopy.Moreover,the intermediates of CO_(2) photoreduction were identi‐fied based on the in situ diffuse reflectance infrared Fourier‐transform spectra.Density functional theory calculations showed that CO_(2) hydrogenation is the rate‐determining step for yielding CH_(4) and CO.Introducing Bi_(2)MoO_(6) into the composite further decreased the energy barrier for CO_(2) photoreduction on BiOI by 0.35 eV.This study verifies the synergistic effect of the S‐scheme heterojunction and van der Waals heterojunction in the 2D/2D composite.
文摘The photoreduction of CO_(2)to achieve high-value-added hydrocarbons under simulated sunlight irradiation is advantageous,but challenging.In this study,a series of MgO and Au nanoparticle-co-modified g-C_(3)N_(4)photocatalysts were synthesized and subsequently applied for the photocatalytic reduction of CO_(2)with H2O under simulated solar irradiation.The best photocatalytic performance was demonstrated by the Au and 3%MgO-co-modified g-C_(3)N_(4)photocatalysts with CO,CH_(4),CH3OH,and CH3CHO yields of 423.9,83.2,47.2,and 130.4μmol/g,respectively,in a 3-h reaction.We investigated the effects of MgO and Au as cocatalysts on photocatalytic behaviors,respectively.The characterizations and experimental results showed that the enhanced photocatalytic activity was due to the synergistic effect among the components of the ternary photocatalyst.The cocatalyst MgO can activate CO_(2)(adsorbed at the interface between the MgO and Au particles),and the Mg-N bonds formed in the MgO-CN nanosheets played an important role in the charge transfer.Meanwhile,the Au particles that were modified into MgO/g-C_(3)N_(4)can increase the absorption of visible light via the surface plasmon resonance effect and further reduce the activation energies of the photoreduction of CO_(2)using H2O.This study provided an effective method for the modification of traditional primary photocatalysts with promising performance for photocatalytic CO_(2)reduction.
基金This work was financially supported in part by the National Natural Science Foundation of China(Grant Nos.12047564,52071041,12074048)the Project for Fundamental and Frontier Research in Chongqing(cstc2020jcyj-msxmX0777 and cstc2020jcyj-msxmX0796)+1 种基金the Fundamental Research Funds for the Central Universities(cqu2018CDHB1A09,106112016CDJZR308808)Open access funding provided by Shanghai Jiao Tong University
文摘Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to navigate the photocatalytic CO_(2) reduction reaction(CRR).Herein,we elucidate the behaviors of isotype heterojunctions toward photocatalytic CRR over a representative photocatalyst,g-C_(3)N_(4).Impressively,the isotype heterojunctions possess a significantly higher efficiency for the spatial separation and transfer of photogenerated carriers than the single components.Along with the intrinsically outstanding stability,the isotype heterojunctions exhibit an exceptional and stable activity toward the CO_(2) photoreduction to CO.More importantly,by combining quantitative in situ technique with the first-principles modeling,we elucidate that the enhanced photoinduced charge dynamics promotes the production of key intermediates and thus the whole reaction kinetics.
基金supported by the Science and Technology Department of Guizhou Province(No.Qiankehe LH zi [2017]7334hao)the China Postdoctoral Science Foundation(No.2017M613005)+2 种基金Foundation of Guizhou Educational Committee(No.Qian jiao he KY[2016]135)the National Natural Science Foundation of China(No.41563012)the Doctoral Scientific Research Foundation of Guizhou Normal University for 2014
文摘Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects of different concentrations of living/dead algae species,including Aphanizomenon flosaquae (AF) and Microcystis aeruginosa (MA),on the photoreduction rate of Hg2+ under various light conditions.The experimental results showed that percentage reduction of Hg2+ was significantly influenced by radiation wavelengths,and dramatically decreased with the presence of algae.The highest percentage reduction of Hg2+ was induced by UV-A,followed by UV-B,visible light and dark for both living and dead AF,and the order was dark > UV-A > UV-B > visible light for both living and dead MA.There were two aspects,i.e.,energy and attenuation rate of light radiation and excrementitious generated from algae metabolisms,were involved in the processes of Hg2+ photoreduction with the presence of algae under different light conditions.The percentage reduction of Hg2+ decreased from 15% to 11% when living and dead AF concentrations increased by 10 times (from 106 to 105 cells/mL),and decreased from11% to ~9% in the case of living and dead MA increased.Algae can adsorb Hg2+ and decrease the concentration of free Hg2+,thus inhibiting Hg2+ photoreduction,especially under the conditions with high concentrations of algae.No significant differences were found in percentage reduction of Hg2+ between living and dead treatments of algae species.The results are of great importance for understanding the role of algae in Hg2+ photoreduction.
基金supported by the National Natural Science Foundation of China(Nos.51772183.52072230)the Yulin Science and Technology Project(No.CXY-2020-040)。
文摘The BiOCl(BOC)synthesized by the water bath heating method was treated with sodium borohydride(NaBH_(4))to introduce oxygen vacancies(OVs).At the same time,Au nanoparticles were loaded to prepare a series of Au/BiOCl samples with different ratios.OVs and Au nanoparticles can promote the light absorption of host photocatalyst in the visible region.The calculated work function of BiOCl and Au can verify the existence of Ohmic contact between the interface of them,which is conducive to the separation of charge carriers.Through a series of photoelectric tests,it was verified experimentally that the separation of charge carriers is indeed enhanced.The high-energy hot electrons produced by Au under the surface plasmon resonance(SPR)effect can increase the counts of electrons to participate in the CO_(2)reduction reaction.Especially for 1.0%-Au/BOC,the yields of CO can reach 43.16μmol g^(−1)h^(−1),which is 6.6 times more than that of BOC.Therefore,loading precious metal on semiconductors is an effective strategy to promote the photocatalytic performance of CO_(2)reduction reactions.
文摘Efficiently converting CO_(2)and H_(2)O into value-added chemicals using solar energy is a viable approach to address global warming and the energy crisis.However,achieving artificial photocatalytic CO_(2)reduction using H_(2)O as the reductant poses challenges is due to the difficulty in efficient cooperation among multiple functional moieties.Metal-organic frameworks(MOFs)are promising candidates for overall CO_(2)photoreduction due to their large surface area,diverse active sites,and excellent tailorability.In this study,we designed a metal-organic framework photocatalyst,named PCN-224(Zn)-Bpy(Ru),by integrating photoactive Zn(Ⅱ)-porphyrin and Ru(Ⅱ)-bipyridyl moieties.In comparison,two isostructural MOFs just with either Zn(Ⅱ)-porphyrin or Ru(Ⅱ)-bipyridyl moiety,namely PCN-224-Bpy(Ru)and PCN-224(Zn)-Bpy were also synthesized.As a result,PCN-224(Zn)-Bpy(Ru)exhibited the highest photocatalytic conversion rate of CO_(2)to CO,with a production rate of 7.6μmol·g^(-1)·h^(-1)in a mixed solvent of CH_(3)CN and H_(2)O,without the need for co-catalysts,photosensitizers,or sacrificial agents.Mass spectrometer analysis detected the signals of^(13)CO(m/z=29),^(13)C^(18)O(m/z=31),^(16)O^(18)O(m/z=34),and^(18)O_(2)(m/z=36),confirming that CO_(2)and H_(2)O acted as the carbon and oxygen sources for CO and O_(2),respectively,thereby confirming the coupling of photocatalytic CO_(2)reduction with H_(2)O oxidation.In contrast,using PCN-224-Bpy(Ru)or PCN-224(Zn)-Bpy as catalysts under the same conditions resulted in significantly lower CO production rates of only 1.5 and 0μmol·g^(-1)·h^(-1),respectively.Mechanistic studies revealed that the lowest unoccupied molecular orbital(LUMO)potential of PCN-224(Zn)-Bpy(Ru)is more negative than the redox potentials of CO_(2)/CO,and the highest occupied molecular orbital(HOMO)potential is more positive than that of H_(2)O/O_(2),satisfying the thermodynamic requirements for overall photocatalytic CO_(2)reduction.In comparison,the HOMO potential of PCN-224(Zn)-Bpy without Ru(II)-bipyridyl moieties is less positive than that of H_(2)O/O_(2),indicating that the Ru(II)-bipyridyl moiety is thermodynamically necessary for CO_(2)reduction coupled with H_(2)O oxidation.Additionally,photoluminescence spectroscopy revealed that the fluorescence of PCN-224(Zn)-Bpy(Ru)was almost completely quenched,and a longer average photoluminescence lifetime compared to PCN-224(Zn)-Bpy and PCN-224-Bpy(Ru)was observed.These suggest a low recombination rate of photogenerated carriers in PCN-224(Zn)-Bpy(Ru),which also supported by the higher photocurrent observed in PCN-224(Zn)-Bpy(Ru)compared to PCN-224(Zn)-Bpy and PCN-224-Bpy(Ru).In summary,the integrated Zn(II)-porphyrin and Ru(II)-bipyridyl moieties in PCN-224(Zn)-Bpy(Ru)play important roles of a photosensitizer and CO_(2)reduction as well as H_(2)O oxidation sites,and their efficient cooperation optimizes the band structure,thereby facilitating the coupling of CO_(2)reduction with H_(2)O oxidation and resulting in highperformance artificial photocatalytic CO_(2)reduction.
基金the Ministry of Education (MOE), Universiti Kebangsaan Malaysia and Universiti Malaysia Pahang for financial support of this research under RAGS (RDU131418) and FRGS (RDU120112)
文摘The performance of CeO2-TiO2 photocatalyst for the photocatalytic reduction of CO2 into methanol was studied under visible light irradiation. The as-prepared catalysts were characterized for their structural, textural and optical properties using X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, X-ray photoelectron spectroscopy（XPS）, nitrogen physisorption analysis, UV-vis spectroscopy and photoluminescence（PL） spectroscopy. The characterization results indicated that the presence of CeO2 stabilized the anatase phase of TiO2, decreased its crystallite size, increased the surface area, reduced the band gap energy and lowered the rate of electron-hole pair recombination. The CeO2-TiO2 photocatalyst showed an increased methanol yield of 18.6 μmol/g under visible light irradiation, compared to the bare TiO2（6.0 μmol/g）.
基金provided by the NSERC Discovery grant # 341960-2013Canada Research Chairs Program to N.O. Scholarships to Erin Mann from NSERC CREATE and Memorial University of Newfoundland
文摘Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride（Cl-） concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg（0） in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0–10 μg/g Cl-, and irradiated with 3.52–5.78 W·m-2 UV（280–400 nm）radiation in a Luz Chem photoreactor. Photoreduction rate constants（k）（0.14–0.59 hr-1） had positive linear relationships with [Cl-], while photoreduced Hg amounts（Hg（Ⅱ）red） had negative linear relationships with [Cl-]（1287–64 pg in 200 g melted snow）. Varying UV and[Cl-] both altered Hg（Ⅱ）red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading,our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow（smaller Hg（Ⅱ）red expected）, but the Hg in the melted snow that is photoreduced may do so more quickly（larger k expected）.
基金The financial supports from National Natural Science Foundation of China(No.22176077)Natural Science Foundation of Gansu Province,China(Nos.20JR10RA615,21ZD8JA006)fundamental research funds for the central universities(No.lzujbky-2021-sp29)are acknowledged。
文摘Uranium removal from aqueous solutions using environmentally friendly photocatalytic technology is a novel approach for resource recovery.Herein,carbon nitride/activated carbon composite materials(CN/AC)were investigated for U(Ⅵ)reduction under visible light.An exceptional boost in photocatalytic activity was observed for CN/AC composites(up to 70 times over the conventional bulk g-C_(3)N_(4)).The strong interactive conjugatedπ-bond structure between g-C_(3)N_(4) and AC accelerated the migration of carriers and then prolonged the electron lifetime.CN/AC composites exhibited excellent compatibility with different water substrates and were resilience to a wide range of p H changes and abundant competitive anions/cations.Quenching experiments and electron microscopy characterization indicated that U(VI)was reduced by photogenerated electrons and deposited on the edge of CN/AC composites.The low-cost,high-performance carbon-based composite material proposed in this work is a potential candidate for the efficient treatment of radioactive wastewater.
文摘COphotoreduction is an attractive process which allows the storage of solar energy and synthesis of solar fuels. Many different photocatalytic systems have been developed, while the alternative photo-reactors are still insufficiently investigated. In this work, photoreduction of COwith HO into CHwas investigated in a modified concentrating solar reactor, using TiOand Pt/TiOas the catalysts. The TiOand Pt/TiOsamples were extensively characterized by different techniques including powder X-ray diffraction（XRD）, Nadsorption/desorption and UV–vis absorption. The catalytic performance of the TiOand Pt/TiOsamples in the gas phase was evaluated under unconcentrated and concentrated Xe-lamp light and nature solar light with different concentrating ratios. Various parameters of the reaction system and the catalysts were investigated and optimized to maximize the catalytic performance of COreduction system. Compared with the normal light irradiation, the TiOand Pt/TiOsamples show higher photocatalytic activity（about 6–7 times） for reducing COinto CHunder concentrated Xe-lamp light and nature solar light. In the range of experimental light intensity, it is found that the concentration of the light makes it suitable for the catalytic reaction, and increases the utilization efficiency of the TiOand Pt/TiOsamples while does not decrease the quantum efficiency.
基金Jilin Province Science and Technology Development Program,Grant/Award Number:20190201233JCProject for Self-innovation Capability Construction of Jilin Province Development and Reform Commission,Grant/Award Number:2021C026+3 种基金Program for JLU Science and Technology Innovative Research Team,Grant/Award Numbers:JLUSTIRT,2017TD-09National Natural Science Foundation of China,Grant/Award Numbers:12034002,51872116Natural Science Funds for Distinguished Young Scholar of Heilongjiang Province,Grant/Award Number:JC2018004Excellent Young Foundation of Harbin Normal University,Grant/Award Number:XKYQ201304。
文摘Retaining the ultrathin structure of two-dimensional materials is very important for stabilizing their catalytic performances.However,aggregation and restacking are unavoidable,to some extent,due to the van der Waals interlayer interaction of two-dimensional materials.Here,we address this challenge by preparing an origami accordion structure of ultrathin twodimensional graphitized carbon nitride(oa-C_(3)N_(4))with rich vacancies.This novel structured oa-C_(3)N_(4) shows exceptional photocatalytic activity for the CO_(2) reduction reaction,which is 8.1 times that of the pristine C_(3)N_(4).The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects,which leads to modification of the electronic structure,regulation of the CO_(2) adsorption energy,and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction.This study provides a new avenue for the development of stable highperformance two-dimensional catalytic materials.
