A catalyst consisting of platinum nanoparticles on a ZIF-8 support(Pt@ZIF-8) was synthesized in a straightforward one-step procedure,by adding a nanostructured platinum sol during the formation of ZIF-8 at room temp...A catalyst consisting of platinum nanoparticles on a ZIF-8 support(Pt@ZIF-8) was synthesized in a straightforward one-step procedure,by adding a nanostructured platinum sol during the formation of ZIF-8 at room temperature.Pt@ZIF-8 was highly porous and well crystallized.The Pt nanoparticles were well dispersed within the ZIF-8 support.In the hydrogenation of 1,4-butynediol,Pt@ZIF-8 exhibited high activity,excellent selectivity for 1,4-butenediol of greater than 94%,and reusability.The Pt@ZIF-8 catalyst did not require further additives.The favorable catalytic performance was attributed primarily to the modification of the ZIF-8 support by the platinum nanoparticles.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
Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelect...Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.展开更多
The oxygen reduction reaction(ORR)on the cathode of a polymer electrolyte fuel cell requires the use of a catalyst based on Pt,one of the most expensive metals on the earth.A number of strategies,including optimizatio...The oxygen reduction reaction(ORR)on the cathode of a polymer electrolyte fuel cell requires the use of a catalyst based on Pt,one of the most expensive metals on the earth.A number of strategies,including optimization of a different metal into the core,have been investigated to enhance the activity of a Pt-based catalyst and thus reduce the loading of Pt.By dedicating to compounding high catalytic activity Pt_(2.7)Pd_(0.3)Ni concave cubic with high index crystal face,the paper shows that concave structures can offer more active site and high level of catalytic activity and if mixed with other metal,decrease the proportion of Pt and improve its mass activity.The paper also makes an exploration into the theory and conditions behind the formation of Pt_(2.7)Pd_(0.3)Ni concave cubic structure,and investigates the difference it demonstrates by modifying the reactive conditions.The results of the oxygen reduction performance of the electrochemical test are as follows:the concave cube-shaped Pt-Pd-Ni catalyst has a mass activity of 1.28 A mg_(Pt)^(–1) at 0.9 V,its highest mass activity is 8.20 times that of commercial Pt/C,and its specific activity is 8.68 times of that commercial Pt/C.And the Pt-Pd-Ni ternary nanocage has excellent structural invariance.After the stability test,there is no obvious structural change and performance degradation in the nanostructure.展开更多
Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide(H_(2)O_(2)).The current challenges concern seeking low-cost,highly active,and selective electro...Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide(H_(2)O_(2)).The current challenges concern seeking low-cost,highly active,and selective electrocatalysts.Cobalt-nitrogen-doped carbon containing catalytically active cobalt-nitrogen(Co-N_(x))sites is an emerging class of materials that can promote the electrochemical generation of H_(2)O_(2).Here,we report a straightforward method for the preparation of cobalt-nitrogen-doped carbon composed of a number of Co-N_(x)moieties using low-energy dry-state ball milling,followed by controlled pyrolysis.This scalable method uses inexpensive materials containing cobalt acetate,2-methylimidazole,and Ketjenblack EC-600JD as the metal,nitrogen,and carbon precursors,respectively.Electrochemical measurements in an acidic medium show the present material exhibits a significant increase in the oxygen reduction reaction current density,accompanied by shifting the onset potential into the positive direction.The current catalyst has also demonstrated an approximate 90%selectivity towards H_(2)O_(2)across a wide range of potential.The H_(2)O_(2)production rate,as measured by H_(2)O_(2)bulk electrolysis,has reached 100 mmol g_(cat).^(–1)h^(–1)with high H_(2)O_(2)faradaic efficiency close to 85%(for 2 h at 0.3 V vs.RHE).Lastly,the catalyst durability has been tested(for 6 h at 0.3 V vs.RHE).The catalyst has shown relatively consistent performance,while the overall faradic efficiency reaches approximate 85%throughout the test cycle indicating the promising catalyst durability for practical applications.The formed Co-N_(x)moieties,along with other parameters,including the acidic environment and the applied potential,likely are the primary reasons for such high activity and selectivity to H_(2)O_(2)production.展开更多
This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glas...This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glass(FTO)and photoactive thin films such as hematite for low‐cost water oxidation reaction.High‐resolution electron microscopy(SEM,TEM,STEM),atomic force microscopy(AFM),elemental chemical mapping(EELS,EDS)and photoelectrochemical(PEC)investigations reveal that the mechanical stress,lattice mismatch,electron energy barrier,and voids between FTO and hematite at the back‐contact interface as well as short‐circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions,thus increasing the overall efficiency of these low‐cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water‐splitting.These findings are of significant importance to improve the charge collection efficiency by minimizing electron‐hole recombination observed at back‐contact interfaces and grain boundaries in mesoporous electrodes,thus improving the overall efficiency and scalability of low‐cost PEC water splitting devices.展开更多
Photocatalytic water oxidation based on semiconductors usually suffers from poor charge transfer from the bulk to the interface,which is necessary for oxygen generation.Here,we construct a hybrid artificial photosynth...Photocatalytic water oxidation based on semiconductors usually suffers from poor charge transfer from the bulk to the interface,which is necessary for oxygen generation.Here,we construct a hybrid artificial photosynthesis system for photocatalytic water oxidation.The system consists of BiVO4as the light harvester,a transitional metal complex(M(dca)2,M=Co,Ni,dca:dicyanamide)as the water oxidation catalyst,and S2O82?as a sacrificial electron acceptor.The system exhibits enhanced oxygen evolution activity when M(dca)2is introduced.The BiVO4/Co(dca)2and Bi‐VO4/Ni(dca)2systems exhibit excellent oxygen evolution rates of508.1and297.7μmol/(h·g)compared to the pure BiVO4which shows a photocatalytic oxygen evolution rate of252.2μmol/(h·g)during6h of photocatalytic reaction.Co(dca)2is found to be more effective than Ni(dca)2as a water oxidation catalyst.The enhanced photocatalytic performance is ascribed to the M(dca)2‐engineered BiVO4/electrolyte interface energetics,and to the M(dca)2‐catalyzed surface water oxidation.These two factors lead to a decrease in the energy barrier for hole transfer from the bulk to the surface of BiVO4,which promotes the water oxidation kinetics.展开更多
The aim of this study is to find an optimal design for a distributed hybrid renewable energy system(HRES) for a residential house in the UK. The hybrid system, which consists of wind turbines, PV arrays, a biodiesel g...The aim of this study is to find an optimal design for a distributed hybrid renewable energy system(HRES) for a residential house in the UK. The hybrid system, which consists of wind turbines, PV arrays, a biodiesel generator, batteries and converters, is designed to meet the known dynamic electrical load of the house and make use of renewable energy resources available locally. Hybrid Optimization Model for Electric Renewables(HOMER) software is used for this study. Different combinations of wind turbines, PV arrays, a biodiesel generator and batteries are evaluated and compared using the NPC(Net Present Cost) method to find the optimal solutions. The HRES is modeled, simulated and optimized using HOMER. The results showed that the wind-biodiesel engine-battery system was the best with the lowest NPC(USD 60254) and the lowest COE(Cost of Energy, USD 0.548/k Wh) while the second best system added PV arrays. This study gives evidence of the key contribution wind turbines make to HRES due to abundant wind resources in the UK, especially in Wales.展开更多
基金supported by the National Natural Science Foundation of China(21573031 and 21428301)the Fundamental Research Funds for the Central Universities(DUT15ZD106 and DUT15RC(4)09)~~
文摘A catalyst consisting of platinum nanoparticles on a ZIF-8 support(Pt@ZIF-8) was synthesized in a straightforward one-step procedure,by adding a nanostructured platinum sol during the formation of ZIF-8 at room temperature.Pt@ZIF-8 was highly porous and well crystallized.The Pt nanoparticles were well dispersed within the ZIF-8 support.In the hydrogenation of 1,4-butynediol,Pt@ZIF-8 exhibited high activity,excellent selectivity for 1,4-butenediol of greater than 94%,and reusability.The Pt@ZIF-8 catalyst did not require further additives.The favorable catalytic performance was attributed primarily to the modification of the ZIF-8 support by the platinum nanoparticles.
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.
文摘Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.
文摘The oxygen reduction reaction(ORR)on the cathode of a polymer electrolyte fuel cell requires the use of a catalyst based on Pt,one of the most expensive metals on the earth.A number of strategies,including optimization of a different metal into the core,have been investigated to enhance the activity of a Pt-based catalyst and thus reduce the loading of Pt.By dedicating to compounding high catalytic activity Pt_(2.7)Pd_(0.3)Ni concave cubic with high index crystal face,the paper shows that concave structures can offer more active site and high level of catalytic activity and if mixed with other metal,decrease the proportion of Pt and improve its mass activity.The paper also makes an exploration into the theory and conditions behind the formation of Pt_(2.7)Pd_(0.3)Ni concave cubic structure,and investigates the difference it demonstrates by modifying the reactive conditions.The results of the oxygen reduction performance of the electrochemical test are as follows:the concave cube-shaped Pt-Pd-Ni catalyst has a mass activity of 1.28 A mg_(Pt)^(–1) at 0.9 V,its highest mass activity is 8.20 times that of commercial Pt/C,and its specific activity is 8.68 times of that commercial Pt/C.And the Pt-Pd-Ni ternary nanocage has excellent structural invariance.After the stability test,there is no obvious structural change and performance degradation in the nanostructure.
文摘Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide(H_(2)O_(2)).The current challenges concern seeking low-cost,highly active,and selective electrocatalysts.Cobalt-nitrogen-doped carbon containing catalytically active cobalt-nitrogen(Co-N_(x))sites is an emerging class of materials that can promote the electrochemical generation of H_(2)O_(2).Here,we report a straightforward method for the preparation of cobalt-nitrogen-doped carbon composed of a number of Co-N_(x)moieties using low-energy dry-state ball milling,followed by controlled pyrolysis.This scalable method uses inexpensive materials containing cobalt acetate,2-methylimidazole,and Ketjenblack EC-600JD as the metal,nitrogen,and carbon precursors,respectively.Electrochemical measurements in an acidic medium show the present material exhibits a significant increase in the oxygen reduction reaction current density,accompanied by shifting the onset potential into the positive direction.The current catalyst has also demonstrated an approximate 90%selectivity towards H_(2)O_(2)across a wide range of potential.The H_(2)O_(2)production rate,as measured by H_(2)O_(2)bulk electrolysis,has reached 100 mmol g_(cat).^(–1)h^(–1)with high H_(2)O_(2)faradaic efficiency close to 85%(for 2 h at 0.3 V vs.RHE).Lastly,the catalyst durability has been tested(for 6 h at 0.3 V vs.RHE).The catalyst has shown relatively consistent performance,while the overall faradic efficiency reaches approximate 85%throughout the test cycle indicating the promising catalyst durability for practical applications.The formed Co-N_(x)moieties,along with other parameters,including the acidic environment and the applied potential,likely are the primary reasons for such high activity and selectivity to H_(2)O_(2)production.
基金supported by CNPq,CAPES,FAPESP(2017/02317-2),FAPESP(2017/11986-5)Shell and the strategic importance of the support given by ANP(Brazil’s National Oil,Natural Gas and Biofuels Agency)through the R&D levy regulation+2 种基金PRH49/UFABC-ANP for the fellowshipthe National Natural Science Foundation of China(NSFC)the Outstanding Talent Program of Shaanxi Province as well as FAPESP(2017/11986-5)
文摘This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glass(FTO)and photoactive thin films such as hematite for low‐cost water oxidation reaction.High‐resolution electron microscopy(SEM,TEM,STEM),atomic force microscopy(AFM),elemental chemical mapping(EELS,EDS)and photoelectrochemical(PEC)investigations reveal that the mechanical stress,lattice mismatch,electron energy barrier,and voids between FTO and hematite at the back‐contact interface as well as short‐circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions,thus increasing the overall efficiency of these low‐cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water‐splitting.These findings are of significant importance to improve the charge collection efficiency by minimizing electron‐hole recombination observed at back‐contact interfaces and grain boundaries in mesoporous electrodes,thus improving the overall efficiency and scalability of low‐cost PEC water splitting devices.
基金supported by the National Natural Science Foundation of China (51672210, 51323011, 51236007)~~
文摘Photocatalytic water oxidation based on semiconductors usually suffers from poor charge transfer from the bulk to the interface,which is necessary for oxygen generation.Here,we construct a hybrid artificial photosynthesis system for photocatalytic water oxidation.The system consists of BiVO4as the light harvester,a transitional metal complex(M(dca)2,M=Co,Ni,dca:dicyanamide)as the water oxidation catalyst,and S2O82?as a sacrificial electron acceptor.The system exhibits enhanced oxygen evolution activity when M(dca)2is introduced.The BiVO4/Co(dca)2and Bi‐VO4/Ni(dca)2systems exhibit excellent oxygen evolution rates of508.1and297.7μmol/(h·g)compared to the pure BiVO4which shows a photocatalytic oxygen evolution rate of252.2μmol/(h·g)during6h of photocatalytic reaction.Co(dca)2is found to be more effective than Ni(dca)2as a water oxidation catalyst.The enhanced photocatalytic performance is ascribed to the M(dca)2‐engineered BiVO4/electrolyte interface energetics,and to the M(dca)2‐catalyzed surface water oxidation.These two factors lead to a decrease in the energy barrier for hole transfer from the bulk to the surface of BiVO4,which promotes the water oxidation kinetics.
基金The Project of Guangxi University Outstanding Post-graduate Student AbroadThe Project of Guangxi University for Youth(2018KY1120,2018KY1121)
文摘The aim of this study is to find an optimal design for a distributed hybrid renewable energy system(HRES) for a residential house in the UK. The hybrid system, which consists of wind turbines, PV arrays, a biodiesel generator, batteries and converters, is designed to meet the known dynamic electrical load of the house and make use of renewable energy resources available locally. Hybrid Optimization Model for Electric Renewables(HOMER) software is used for this study. Different combinations of wind turbines, PV arrays, a biodiesel generator and batteries are evaluated and compared using the NPC(Net Present Cost) method to find the optimal solutions. The HRES is modeled, simulated and optimized using HOMER. The results showed that the wind-biodiesel engine-battery system was the best with the lowest NPC(USD 60254) and the lowest COE(Cost of Energy, USD 0.548/k Wh) while the second best system added PV arrays. This study gives evidence of the key contribution wind turbines make to HRES due to abundant wind resources in the UK, especially in Wales.