Monolithic catalysts of Pt/La-Al2O3 and Pt/Ce0.67Zr0.3302 were prepared to investigate methane selective catalytic reduction (SCR) of NO. The results indicate that Pt/Ce0.67Zr0.33O2 shows high activity and both NO a...Monolithic catalysts of Pt/La-Al2O3 and Pt/Ce0.67Zr0.3302 were prepared to investigate methane selective catalytic reduction (SCR) of NO. The results indicate that Pt/Ce0.67Zr0.33O2 shows high activity and both NO and CH4 can be converted completely at 450℃. Meanwhile, NO and CH4 can be converted completely when there exists excess oxygen. The Pt/Ce0.67Zr0.33O2 catalyst were further investigated by using methane as reducing agent to SCR NO in a novel equipment which combined the CH4 selective catalytic reduction of NO with methane combustion. The result shows that the catalyst is high active and the novel equipment is very effective. The conversion of NO is above 92% under the conditions used in this work. The prepared burner and catalysts have great potential for application.展开更多
Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of ...Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of 0.1 m A/cm2, and the capacity is about 2.3 times as that of the pristine KB. When the batteries are cycled with different restricted capacity, the boron-doped Ketjenblack based cathodes exhibits higher discharge platform and longer cycle life than Ketjenblack based cathodes. Additionally, the boron-doped Ketjenblack also shows a superior electrocatalytic activity for oxygen reduction in 0.1 mol/L KOH aqueous solution. The improvement in catalytic activity results from the defects and activation sites introduced by boron doping.展开更多
There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attra...There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion reactions.Its versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and functionalization.Here,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.展开更多
Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization...Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization of condensation mixtures of alpha-keto ester 5 with carbomite. In the second route the key step was reduction of oxime 8, derived from alpha-keto ester 5, with iron powder in the presence of acetic anhydride.展开更多
Hydrogen peroxide(H_(2)O_(2))is a chemical that is widely of interest in both environmental and energy fields.On the one hand,as a clean oxidant,H_(2)O_(2)has been commonly used in the field of bleaching,disinfection,...Hydrogen peroxide(H_(2)O_(2))is a chemical that is widely of interest in both environmental and energy fields.On the one hand,as a clean oxidant,H_(2)O_(2)has been commonly used in the field of bleaching,disinfection,and advanced oxidation processes.On the other hand,H_(2)O_(2)has also been explored as a liquid fuel alternative to H_(2)or fossil fuels in fuel cells due to its high energy density.However,the current industrial production of H_(2)O_(2)relies on the anthraquinone(AO)method that involves palladium-catalyzed hydrogenation-oxidation steps.展开更多
Designing highly efficient photocatalyst for hydrogen peroxide(HO)production is an ideal strategy to avoid the shortcomings of traditional HOproduction and to realize the conversion of solar energy to chemical energy....Designing highly efficient photocatalyst for hydrogen peroxide(HO)production is an ideal strategy to avoid the shortcomings of traditional HOproduction and to realize the conversion of solar energy to chemical energy.In this work,a step-scheme(S-scheme)heterojunction photocatalyst composed of Zn O and WOis carefully prepared by hydrothermal and calcination method for efficient photocatalytic HOproduction.The ZW30 composite photocatalysts exhibit enhanced activity with the highest HO-production rate of 6788μmol Lh.The results show that the photocatalytic HOproduction process is dominated by a direct two-electron Oreduction pathway.The enhanced photocatalytic HO-production activity is attributed to the formation of interfacial internal electric field(IEF)in the S-scheme heterojunction,which boosts the spatial separation of charge carriers and enables electrons with the strongest reduction power to participate in HOproduction.This work provides an in-depth insight of the great advantages of S-scheme heterojunction in photocatalytic HOproduction.展开更多
Lake littoral zones are characterized by heterogeneity in the biogeochemistry of nutrient elements. This study aimed to explore the relationship between the nitrous oxide reductase gene (nosZ)-encoding denitrifier c...Lake littoral zones are characterized by heterogeneity in the biogeochemistry of nutrient elements. This study aimed to explore the relationship between the nitrous oxide reductase gene (nosZ)-encoding denitrifier community composition/abundance and N2O reduction. Five samples (deep sediment, near-transition sediment, transition site, near-transition land and land soil) were collected along a littoral gradient of eutrophic Baiyangdian Lake, North China. To investigate the relationship between the nosZ-encoding denitrifier community structure and N20 reduction, the nosZ-encoding denitrifier community composition/abundance, potential denitrification rate (DNR) and potential N20 production rate (pN20) were investigated using molecular biological technologies and laboratory incubation experiments. The results showed that the average DNR of sediments was about 25 times higher than that of land soils, reaching 282.5 nmol N/(g dry weight (dw).hr) and that the average pN20 of sediments was about 3.5 times higher than that of land soils, reaching 15.7 nmol N/(g dw-hr). In the land area, the nosZ gene abundance showed a negative correlation with the N20/(N20+N2) ratio, indicating that nosZ gene abundance dominated N20 reduction both in the surface soils of the land area and in the soil core of the transition site. Phylogenetic analysis showed that all the nosZ sequences recovered from sediment clustered closely with the isolates Azospirillum largimobile and Azospirillum irakense affiliated to Rhodospirillaceae in alpha-Proteobacteria, while about 92.3% (12/13) of the nosZ sequences recovered from land soil affiliated to Rhizobiaceae and Bradyrhizobiaceae in a-Proteobacteria. The community composition of nosZ gene-encoding denitrifiers appeared to be coupled with N20 reduction along the littoral gradient.展开更多
N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalyst...N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst (Pt/BaO/Al203 + Pd/Al2O3) and Pt-Pd co-impregnation catalyst (Pt-Pd/BaO/Al2O3) were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 (Pt/BaO/Al2O3 + Pd/Al2O3) produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over (Pt-Pd/BaO/Al2O3 + Al2O3). Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in (Pt/BaO/Al2O3 + Pd/Al2O3) played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over (Pt-Pd/BaO/Al2O3 + Al2O3) was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.展开更多
Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions a...Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.展开更多
Electrocatalysts with high catalytic activity and stability play a key role in promising renewable energy technologies, such as fuel cells and metal-air batteries. Here, we report the synthesis of Fe/Fe203 nanoparticl...Electrocatalysts with high catalytic activity and stability play a key role in promising renewable energy technologies, such as fuel cells and metal-air batteries. Here, we report the synthesis of Fe/Fe203 nanoparticles anchored on Fe-N-doped carbon nanosheets (Fe/Fe2Og@Fe-N-C) using shrimp shell-derived N-doped carbon nanodots as carbon and nitrogen sources in the presence of FeCI3 by a simple pyrolysis approach. Fe/Fe203@Fe-N-C obtained at a pyrolysis temperature of 1,000 ℃ (Fe/Fe2OB@Fe-N-C-1000) possessed a mesoporous structure and high surface area of 747.3 m2-g-1. As an electrocatalyst, Fe/Fe203@Fe-N-C-1000 exhibited bifunctional electrocatalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media, com- parable to that of commercial Pt/C for ORR and RuO2 for OER, respectively. The Zn-air battery test demonstrated that Fe/Fe2OB@Fe-N-C-1000 had a superior rechargeable performance and cycling stability as an air cathode material with an open drcuit voltage of 1.47 V (vs. Ag/AgCl) and a power density of 193 mW.cm-2 at a current density of 220 mA-cm-2. These performances were better than other commercial catalysts with an open circuit voltage of 1.36 V and a power density of 173 mW-cm^-2 at a current density of 220 mA.cm-2 (a mixture of commercial Pt/C and RuO2 with a mass ratio of 1:1 was used for the rechargeable Zn-air battery measurements). This work will be helpful to design and develop low-cost and abundant bifunctional oxygen electrocatalysts for future metal-air batteries.展开更多
基金Supported by the National High Technology Research and Development Program of China (863 Program, 2006AA06Z347)the NationalNatural Science Foundation of China (20773090).
文摘Monolithic catalysts of Pt/La-Al2O3 and Pt/Ce0.67Zr0.3302 were prepared to investigate methane selective catalytic reduction (SCR) of NO. The results indicate that Pt/Ce0.67Zr0.33O2 shows high activity and both NO and CH4 can be converted completely at 450℃. Meanwhile, NO and CH4 can be converted completely when there exists excess oxygen. The Pt/Ce0.67Zr0.33O2 catalyst were further investigated by using methane as reducing agent to SCR NO in a novel equipment which combined the CH4 selective catalytic reduction of NO with methane combustion. The result shows that the catalyst is high active and the novel equipment is very effective. The conversion of NO is above 92% under the conditions used in this work. The prepared burner and catalysts have great potential for application.
基金supported by the MOST(Grant nos.2013CB934000and 2014DFG71590)Beijing Municipal Program(Grant no.YETP0157)
文摘Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of 0.1 m A/cm2, and the capacity is about 2.3 times as that of the pristine KB. When the batteries are cycled with different restricted capacity, the boron-doped Ketjenblack based cathodes exhibits higher discharge platform and longer cycle life than Ketjenblack based cathodes. Additionally, the boron-doped Ketjenblack also shows a superior electrocatalytic activity for oxygen reduction in 0.1 mol/L KOH aqueous solution. The improvement in catalytic activity results from the defects and activation sites introduced by boron doping.
基金This study was supported by Korea Hydro&Nuclear Power Co.,Ltd.(No.:2018-Tech-21)the National Research Foundation of Korea(NRF)grant funded by the Korea government MSIT(2019M3E6A1064763).
文摘There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion reactions.Its versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and functionalization.Here,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.
文摘Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization of condensation mixtures of alpha-keto ester 5 with carbomite. In the second route the key step was reduction of oxime 8, derived from alpha-keto ester 5, with iron powder in the presence of acetic anhydride.
文摘Hydrogen peroxide(H_(2)O_(2))is a chemical that is widely of interest in both environmental and energy fields.On the one hand,as a clean oxidant,H_(2)O_(2)has been commonly used in the field of bleaching,disinfection,and advanced oxidation processes.On the other hand,H_(2)O_(2)has also been explored as a liquid fuel alternative to H_(2)or fossil fuels in fuel cells due to its high energy density.However,the current industrial production of H_(2)O_(2)relies on the anthraquinone(AO)method that involves palladium-catalyzed hydrogenation-oxidation steps.
基金the National Natural Science Foundation of China(52073223,51932007,51961135303,U1905215 and 21871217)the China Postdoctoral Science Foundation(2021TQ0310)the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,Saudi Arabia has funded this project,under grant no.(FP-4–43)。
文摘Designing highly efficient photocatalyst for hydrogen peroxide(HO)production is an ideal strategy to avoid the shortcomings of traditional HOproduction and to realize the conversion of solar energy to chemical energy.In this work,a step-scheme(S-scheme)heterojunction photocatalyst composed of Zn O and WOis carefully prepared by hydrothermal and calcination method for efficient photocatalytic HOproduction.The ZW30 composite photocatalysts exhibit enhanced activity with the highest HO-production rate of 6788μmol Lh.The results show that the photocatalytic HOproduction process is dominated by a direct two-electron Oreduction pathway.The enhanced photocatalytic HO-production activity is attributed to the formation of interfacial internal electric field(IEF)in the S-scheme heterojunction,which boosts the spatial separation of charge carriers and enables electrons with the strongest reduction power to participate in HOproduction.This work provides an in-depth insight of the great advantages of S-scheme heterojunction in photocatalytic HOproduction.
基金supported by the National Natural Science Foundation of China (No.21077119)the National Basic Research Program of China(No. 2009CB421103)+3 种基金the Key Project of Water Pollution Control and Management of China (No.2008ZX07209-006, 2009ZX07209-005 and 2008ZX07421-001)the Special Fund of Tianjin Science and Technology Innovation Project (No. 08FDZDSF03200)the support of the Beijing Nova Program (No. 2011095)the K. C. Wong Education Foundation, Hong Kong, China
文摘Lake littoral zones are characterized by heterogeneity in the biogeochemistry of nutrient elements. This study aimed to explore the relationship between the nitrous oxide reductase gene (nosZ)-encoding denitrifier community composition/abundance and N2O reduction. Five samples (deep sediment, near-transition sediment, transition site, near-transition land and land soil) were collected along a littoral gradient of eutrophic Baiyangdian Lake, North China. To investigate the relationship between the nosZ-encoding denitrifier community structure and N20 reduction, the nosZ-encoding denitrifier community composition/abundance, potential denitrification rate (DNR) and potential N20 production rate (pN20) were investigated using molecular biological technologies and laboratory incubation experiments. The results showed that the average DNR of sediments was about 25 times higher than that of land soils, reaching 282.5 nmol N/(g dry weight (dw).hr) and that the average pN20 of sediments was about 3.5 times higher than that of land soils, reaching 15.7 nmol N/(g dw-hr). In the land area, the nosZ gene abundance showed a negative correlation with the N20/(N20+N2) ratio, indicating that nosZ gene abundance dominated N20 reduction both in the surface soils of the land area and in the soil core of the transition site. Phylogenetic analysis showed that all the nosZ sequences recovered from sediment clustered closely with the isolates Azospirillum largimobile and Azospirillum irakense affiliated to Rhodospirillaceae in alpha-Proteobacteria, while about 92.3% (12/13) of the nosZ sequences recovered from land soil affiliated to Rhizobiaceae and Bradyrhizobiaceae in a-Proteobacteria. The community composition of nosZ gene-encoding denitrifiers appeared to be coupled with N20 reduction along the littoral gradient.
基金Acknowledgements This work was financially supported by the National Key Research and Development Program (No. 2017YFC0211002) and the National Natural Science Foundation of China (Grant No. 21476170).
文摘N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst (Pt/BaO/Al203 + Pd/Al2O3) and Pt-Pd co-impregnation catalyst (Pt-Pd/BaO/Al2O3) were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 (Pt/BaO/Al2O3 + Pd/Al2O3) produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over (Pt-Pd/BaO/Al2O3 + Al2O3). Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in (Pt/BaO/Al2O3 + Pd/Al2O3) played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over (Pt-Pd/BaO/Al2O3 + Al2O3) was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.
基金The financial support from the National Natural Science Foundation of China (Nos. 51772312, 21671197)
文摘Green reactions not only provide us chemical products without any pollution,but also offer us the viable technology to realize difficult tasks in normal conditions.Photo-,photoelectro-,and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future.Especially,some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products,such as H2 evolution(H2 production),02 evolution/reduction,CO2 reduction,N2 reduction(or N2 fixation) reactions.We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction(HER),at the same time,we also need highly efficient 02 reduction reaction(ORR) in fuel cells for improving the reaction kinetics.Moreover,we can get the clean oxidant O2 from water through O2 evolution reaction(OER),and carry out some reactions without posing any pollution to reaction systems.Furthermore,we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction(CRR).Last but not the least,we can get ammonia from N2 reduction reaction(NRR),which can decrease energy input compared to the traditional Hubble process.These reactions,such as HER,ORR,OER,CRR and NRR could be realized through solar-,photoelectro-and electro-assisted ways.For them,the catalysts used play crucial roles in determining the efficiency and kinds of products,so we should consider the efficiency of catalysts.However,the cost,synthetic methods of catalysts should also be considered.Nowadays,significant progress has been achieved,however,many challenges still exist,reaction systems,catalysts underlying mechanisms,and so on.As extremely active fields,we should pay attention to them.Under the background,it has motivated us to contribute with a roadmap on ’GasInvolved Photo-and Electro-Catalysis’.
基金This work was financially supported by the National Natural Science Foundation of China (Nos. 51372248 and 51432009), the Instrument Developing Project of the Chinese Academy of Sciences (No. yz201421) and the CAS/SAFEA International Partnership Program for Creative Research Teams of Chinese Academy of Sciences, the CAS Pioneer Hundred Talents Program and the Users with Potential Program (No. 2015HSC- UP006, Hefei Science Center, CAS), China.
文摘Electrocatalysts with high catalytic activity and stability play a key role in promising renewable energy technologies, such as fuel cells and metal-air batteries. Here, we report the synthesis of Fe/Fe203 nanoparticles anchored on Fe-N-doped carbon nanosheets (Fe/Fe2Og@Fe-N-C) using shrimp shell-derived N-doped carbon nanodots as carbon and nitrogen sources in the presence of FeCI3 by a simple pyrolysis approach. Fe/Fe203@Fe-N-C obtained at a pyrolysis temperature of 1,000 ℃ (Fe/Fe2OB@Fe-N-C-1000) possessed a mesoporous structure and high surface area of 747.3 m2-g-1. As an electrocatalyst, Fe/Fe203@Fe-N-C-1000 exhibited bifunctional electrocatalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media, com- parable to that of commercial Pt/C for ORR and RuO2 for OER, respectively. The Zn-air battery test demonstrated that Fe/Fe2OB@Fe-N-C-1000 had a superior rechargeable performance and cycling stability as an air cathode material with an open drcuit voltage of 1.47 V (vs. Ag/AgCl) and a power density of 193 mW.cm-2 at a current density of 220 mA-cm-2. These performances were better than other commercial catalysts with an open circuit voltage of 1.36 V and a power density of 173 mW-cm^-2 at a current density of 220 mA.cm-2 (a mixture of commercial Pt/C and RuO2 with a mass ratio of 1:1 was used for the rechargeable Zn-air battery measurements). This work will be helpful to design and develop low-cost and abundant bifunctional oxygen electrocatalysts for future metal-air batteries.