Compared with general redox chemistry,electrochemistry using the electron as a potent,controllable,yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving select...Compared with general redox chemistry,electrochemistry using the electron as a potent,controllable,yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving selective organic synthesis.With its environmentally benign features gradually being uncovered and studied,organic electrosynthesis is currently undergoing a revival and becoming a rapidly growing area within the synthetic community.Among the electrochemical transformations,the anodically enabled ones have been far more extensively exploited than those driven by cathodic reduction,although both approaches are conceptually attractive.To stimulate the development of cathodically enabled organic reactions,this review summarizes the recently developed reductive electrosynthetic protocols,discussing and highlighting reaction features,substrate scopes,applications,and plausible mechanisms to reveal the recent trends in this area.Herein,cathodic reduction-enabled preparative organic transformations are categorized into four types:reduction of(1)unsaturated hydrocarbons,(2)heteroatom-containing carbon-based unsaturated systems,(3)saturated C-hetero or C–C polar/strained bonds,and(4)hetero-hetero linkages.Apart from net electroreductive reactions,a few examples of reductive photo-electrosynthesis as well as paired electrolysis are also introduced,which offer opportunities to overcome certain limitations and improve synthetic versatility.The electrochemically driven,transition metal-catalyzed reductive cross-couplings that have been comprehensively discussed in several other recent reviews are not included here.展开更多
The effects of cathode potentials and initial nitrate concentrations on nitrate reduction in bio- electrochemical systems （BESs） were reported. These factors could partition nitrate reduction between denitrification...The effects of cathode potentials and initial nitrate concentrations on nitrate reduction in bio- electrochemical systems （BESs） were reported. These factors could partition nitrate reduction between denitrification and dissimilatory nitrate reduction to ammonium （DNRA）. Pseudomonas alcaliphilastrain MBR utilized an electrode as the sole electron donor and nitrate as the sole electron acceptor. When the cathode potential was set from -0.3 to -I.1 V （vs. Ag/AgC1） at an initial nitrate concentration of 100 mg NO^-N/L, the DNRA electron recovery increased from （10.76 ± 1.6）% to （35.06 ± 0.99）%; the denitrification electron recovery decreased from （63.42 ± 1,32）% to （44.33 ± 1.92）%. When the initial nitrate concentration increased from （29.09 ± 0.24） to （490.97 ± 3.49） mg NO3-N/L at the same potential （-0.9 V）, denitrification electron recovery increased from （5.88 ± 1.08）% to （50.19 ±2.59）%; the DNRA electron recovery declined from （48.79 ±1.32）% to （16.02 ± 1.41）%. The prevalence of DNRA occurred at high ratios of electron donors to acceptors in the BESs and denitrification prevailed against DNRA under a lower ratio of electron donors to acceptors. These results had a potential application value of regulating the transformation of nitrate to N2 or ammonium in BESs for nitrate removal.展开更多
The electrochemical degradation ofp-nitrophenol(PNP)under different conditions was investigated.The electrochemical behavior of PNP and its reduction product p-aminophenol(PAP)on stainless steel cathode and Ti/Pt anod...The electrochemical degradation ofp-nitrophenol(PNP)under different conditions was investigated.The electrochemical behavior of PNP and its reduction product p-aminophenol(PAP)on stainless steel cathode and Ti/Pt anode through cyclic voltammetry were observed.Electrochemical degradation process was performed in an undivided cell and 92%PNP was removed corresponding to a 22%total organic carbon removal.A divided cell was also used and it was found that PNP degradation was mainly attributed to cathodic reduction,while anodic oxidation was responsible for PNP removal due to the reaction with hydroxyl radicals and surface oxide generated on the anode.The sequential electrolytic processes,reduction-oxidation and oxidation-reduction,were compared in the divided cell.In the case of reduction-oxidation process,the total organic carbon removal reached 40%,but PNP removal was the same with the undivided cell.A black deposit was found in the effluent and identified by Fourier transform infrared spectroscopy as a polymer of PAP produced by the 1,4-addition reaction of quinoneimine.Intermediates left in the solution such as hydroquinone,p-benzoquinone and PAP were determined by high performance liquid chromatography.Whereas,the oxidation-reduction process proved unsatisfying.展开更多
The use of metal-free carbon nanomaterials as cathodic oxygen reduction reaction(ORR)catalysts has rapidly grown due to their low cost,high electrical conductivity,and great stability.Recent progress has demonstrated ...The use of metal-free carbon nanomaterials as cathodic oxygen reduction reaction(ORR)catalysts has rapidly grown due to their low cost,high electrical conductivity,and great stability.Recent progress has demonstrated that defective carbons co-doped with heteroatoms(e.g.N and S)usually have high activity.However,the role and contribution of the inherent defects and these dopants towards the ORR performance are still unambiguous.Herein,we have stepwise manipulated the heteroatom(N and S)doping,conversion and removal on carbon defects,combined with electrocatalytic performance evaluation,and systematically investigated the synergistic effect between the heteroatoms and carbon defects.The experimental results demonstrated that pyridinic-and pyrrolic-N atoms are more important than graphitic-N atoms for obtaining high ORR activity of the ORR catalyst and they could be considered as active N doping atoms.The synergistic effect of the active N doping atoms and defects is crucial for high ORR activity of the carbon catalyst.Without the active N species,only S doping provides a limited contribution for improving the catalysis performance of defective carbon.However,the S and active N co-doping on defective carbon could boost the acidic ORR performance of the catalyst with a high half-wave potential of 0.77 V in 0.1 M HClO_(4),which is superior to that of most metal-free electrocatalysts reported to date.This work provides an example of studying the catalytic contribution of multiple active centres from the perspective of synthesis control.展开更多
Nitrate-methanol co-electrolysis involving the cathodic nitrate reduction reaction(NO_(3)RR)combined with the anodic methanol oxidation reaction(MOR)is a viable way to synchronously produce ammonia(NH_(3))and formate ...Nitrate-methanol co-electrolysis involving the cathodic nitrate reduction reaction(NO_(3)RR)combined with the anodic methanol oxidation reaction(MOR)is a viable way to synchronously produce ammonia(NH_(3))and formate via gentle,sustainable and energy-saving“E-refining”and“E-reforming”means.An efficient bifunctional catalyst for the NO_(3)RR and MOR is pivotal to achieve such a goal.In this work,a nitrogen-doped carbon-encapsulated nickel iron phosphide hybrid(Ni_(2)FeP@NC)was prepared as a bifunctional catalyst for the NO_(3)RR and MOR,and its electrochemical performance for nitrate-methanol co-electrolysis was investigated.The Ni_(2)FeP@NC catalyst exhibited a high NH_(3) yield(0.47 mmol h^(-1) cm^(-2) at-0.35 V)and faradaic efficiency(FE,93%at-0.15 V)for the NO_(3)RR and simultaneously demonstrated high MOR efficiency for formate production(yield of 1.62 mmol h^(-1) cm^(-2) at 1.7 V and FE of around 95%).The bifunctional catalytic features of the nitrate-methanol co-electrolysis system enabled the concurrent production of NH_(3) and formate at low input voltage.This work provides a viable paradigm for pairwise electrosynthesis of valuable chemicals via“E-refining”and“E-reforming”through the rational design of bifunctional catalysts.展开更多
Arsanilic acid(p-ASA),an organoarsenic additive found in livestock wastewater,can release toxic inorganic arsenic into the environment.While bioelectrochemical systems have proven effective in decomposing organoarseni...Arsanilic acid(p-ASA),an organoarsenic additive found in livestock wastewater,can release toxic inorganic arsenic into the environment.While bioelectrochemical systems have proven effective in decomposing organoarsenics,managing the resulting inorganic arsenic remains a challenge.This study demonstrated the feasibility of a two-stage bioelectrochemical process designed to facilitate p-ASA degradation and in situ recover inorganic arsenic from contaminated livestock wastewater.It consisted of two sequential stages:(I)anodic stimulation for p-ASA degradation and(II)reversing electrode polarities for the cathodic reduction of inorganic arsenic.In Stage I,the anode significantly enhanced the degradation of p-ASA,resulting in 18μg/L of As(III)and 700μg/L of As(V)released into the bulk solution.In Stage II,the cathode further reduced the As(III)and As(V)to 8.9 and 35.5μg/L,respectively,through the synergistic action of the cathode and suspended microbes.The inorganic arsenic was recovered as a layer of As(V)-O on the cathode.Microbial analysis indicated that Alcaligenes was responsible for the degradation of p-ASA,while Anaerobacillus and Desulfitibacter played key roles in reducing As(V)and As(III)on the cathode,respectively.This study provided a promising alternative approach for the removal of organoarsenics and in situ recovery of inorganic arsenic from organoarsenic-bearing wastewater.展开更多
High-temperature proton exchange membrane fuel cells(HT-PEMFCs)have the unique advantages of fast electrode reaction kinetics,high CO tolerance,and simple water and thermal management at their operating temperature(12...High-temperature proton exchange membrane fuel cells(HT-PEMFCs)have the unique advantages of fast electrode reaction kinetics,high CO tolerance,and simple water and thermal management at their operating temperature(120-300℃),which can effectively solve the hydrogen source problem and help achieve the dual-carbon goal.The catalysts in HT-PEMFCs are mainly Pt-based catalysts,which have good catalytic activity in the oxygen reduction reaction(ORR)and hydrogen oxidation reaction(HOR).However,in HT-PEMFCs,the high load of platinum-based catalysts to alleviate the limitation of strong adsorption of phosphoric acid(PA)on the platinum surface on activity expression leads to high cost,insufficient activity,decreased activity under long-term operation and carrier corrosion.The present review mainly summarizes the latest research progress of HT-PEMFCs catalysts,systematically analyzes the application of precious metal and non-precious metal catalysts in HT-PEMFCs,and unveils the structure-activity relationship and anti-PA poisoning mechanism.The current challenges and opportunities faced by HT-PEMFCs are discussed,as well as possible future solutions.It is believed that this review can provide some inspiration for the future development of high-performance HT-PEMFC catalysts.展开更多
基金Beijing Normal University is acknowledged for providing financial support.
文摘Compared with general redox chemistry,electrochemistry using the electron as a potent,controllable,yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving selective organic synthesis.With its environmentally benign features gradually being uncovered and studied,organic electrosynthesis is currently undergoing a revival and becoming a rapidly growing area within the synthetic community.Among the electrochemical transformations,the anodically enabled ones have been far more extensively exploited than those driven by cathodic reduction,although both approaches are conceptually attractive.To stimulate the development of cathodically enabled organic reactions,this review summarizes the recently developed reductive electrosynthetic protocols,discussing and highlighting reaction features,substrate scopes,applications,and plausible mechanisms to reveal the recent trends in this area.Herein,cathodic reduction-enabled preparative organic transformations are categorized into four types:reduction of(1)unsaturated hydrocarbons,(2)heteroatom-containing carbon-based unsaturated systems,(3)saturated C-hetero or C–C polar/strained bonds,and(4)hetero-hetero linkages.Apart from net electroreductive reactions,a few examples of reductive photo-electrosynthesis as well as paired electrolysis are also introduced,which offer opportunities to overcome certain limitations and improve synthetic versatility.The electrochemically driven,transition metal-catalyzed reductive cross-couplings that have been comprehensively discussed in several other recent reviews are not included here.
基金supported by the National Natural Science Foundation of China(No.51074149,31270166,31270531 and 31000070)the West Light Foundation of the Chinese Academy of Sciences
文摘The effects of cathode potentials and initial nitrate concentrations on nitrate reduction in bio- electrochemical systems （BESs） were reported. These factors could partition nitrate reduction between denitrification and dissimilatory nitrate reduction to ammonium （DNRA）. Pseudomonas alcaliphilastrain MBR utilized an electrode as the sole electron donor and nitrate as the sole electron acceptor. When the cathode potential was set from -0.3 to -I.1 V （vs. Ag/AgC1） at an initial nitrate concentration of 100 mg NO^-N/L, the DNRA electron recovery increased from （10.76 ± 1.6）% to （35.06 ± 0.99）%; the denitrification electron recovery decreased from （63.42 ± 1,32）% to （44.33 ± 1.92）%. When the initial nitrate concentration increased from （29.09 ± 0.24） to （490.97 ± 3.49） mg NO3-N/L at the same potential （-0.9 V）, denitrification electron recovery increased from （5.88 ± 1.08）% to （50.19 ±2.59）%; the DNRA electron recovery declined from （48.79 ±1.32）% to （16.02 ± 1.41）%. The prevalence of DNRA occurred at high ratios of electron donors to acceptors in the BESs and denitrification prevailed against DNRA under a lower ratio of electron donors to acceptors. These results had a potential application value of regulating the transformation of nitrate to N2 or ammonium in BESs for nitrate removal.
基金supported by the National Key Science and Technology Project:Water Pollution Control and Remediation(No.2008ZX07208-004-2)the National Natural Science Foundation of China(No.50808029)
文摘The electrochemical degradation ofp-nitrophenol(PNP)under different conditions was investigated.The electrochemical behavior of PNP and its reduction product p-aminophenol(PAP)on stainless steel cathode and Ti/Pt anode through cyclic voltammetry were observed.Electrochemical degradation process was performed in an undivided cell and 92%PNP was removed corresponding to a 22%total organic carbon removal.A divided cell was also used and it was found that PNP degradation was mainly attributed to cathodic reduction,while anodic oxidation was responsible for PNP removal due to the reaction with hydroxyl radicals and surface oxide generated on the anode.The sequential electrolytic processes,reduction-oxidation and oxidation-reduction,were compared in the divided cell.In the case of reduction-oxidation process,the total organic carbon removal reached 40%,but PNP removal was the same with the undivided cell.A black deposit was found in the effluent and identified by Fourier transform infrared spectroscopy as a polymer of PAP produced by the 1,4-addition reaction of quinoneimine.Intermediates left in the solution such as hydroquinone,p-benzoquinone and PAP were determined by high performance liquid chromatography.Whereas,the oxidation-reduction process proved unsatisfying.
基金supported by the NSFC of China(21571139,22035003,22001132 and 22271217).
文摘The use of metal-free carbon nanomaterials as cathodic oxygen reduction reaction(ORR)catalysts has rapidly grown due to their low cost,high electrical conductivity,and great stability.Recent progress has demonstrated that defective carbons co-doped with heteroatoms(e.g.N and S)usually have high activity.However,the role and contribution of the inherent defects and these dopants towards the ORR performance are still unambiguous.Herein,we have stepwise manipulated the heteroatom(N and S)doping,conversion and removal on carbon defects,combined with electrocatalytic performance evaluation,and systematically investigated the synergistic effect between the heteroatoms and carbon defects.The experimental results demonstrated that pyridinic-and pyrrolic-N atoms are more important than graphitic-N atoms for obtaining high ORR activity of the ORR catalyst and they could be considered as active N doping atoms.The synergistic effect of the active N doping atoms and defects is crucial for high ORR activity of the carbon catalyst.Without the active N species,only S doping provides a limited contribution for improving the catalysis performance of defective carbon.However,the S and active N co-doping on defective carbon could boost the acidic ORR performance of the catalyst with a high half-wave potential of 0.77 V in 0.1 M HClO_(4),which is superior to that of most metal-free electrocatalysts reported to date.This work provides an example of studying the catalytic contribution of multiple active centres from the perspective of synthesis control.
基金supported by NSFC(No.51802084)the 111 Project(No.D17007)Henan Center for Outstanding Oversea Scientists(No.GZS_(2)022017).
文摘Nitrate-methanol co-electrolysis involving the cathodic nitrate reduction reaction(NO_(3)RR)combined with the anodic methanol oxidation reaction(MOR)is a viable way to synchronously produce ammonia(NH_(3))and formate via gentle,sustainable and energy-saving“E-refining”and“E-reforming”means.An efficient bifunctional catalyst for the NO_(3)RR and MOR is pivotal to achieve such a goal.In this work,a nitrogen-doped carbon-encapsulated nickel iron phosphide hybrid(Ni_(2)FeP@NC)was prepared as a bifunctional catalyst for the NO_(3)RR and MOR,and its electrochemical performance for nitrate-methanol co-electrolysis was investigated.The Ni_(2)FeP@NC catalyst exhibited a high NH_(3) yield(0.47 mmol h^(-1) cm^(-2) at-0.35 V)and faradaic efficiency(FE,93%at-0.15 V)for the NO_(3)RR and simultaneously demonstrated high MOR efficiency for formate production(yield of 1.62 mmol h^(-1) cm^(-2) at 1.7 V and FE of around 95%).The bifunctional catalytic features of the nitrate-methanol co-electrolysis system enabled the concurrent production of NH_(3) and formate at low input voltage.This work provides a viable paradigm for pairwise electrosynthesis of valuable chemicals via“E-refining”and“E-reforming”through the rational design of bifunctional catalysts.
基金supported by the National Natural Science Foundation of China(No.52300092)the Fundamental Research Funds for the Central Universities,China(No.30923010919)the Key Project of Science and Technology in Anhui Province,China(No.1801041130).
文摘Arsanilic acid(p-ASA),an organoarsenic additive found in livestock wastewater,can release toxic inorganic arsenic into the environment.While bioelectrochemical systems have proven effective in decomposing organoarsenics,managing the resulting inorganic arsenic remains a challenge.This study demonstrated the feasibility of a two-stage bioelectrochemical process designed to facilitate p-ASA degradation and in situ recover inorganic arsenic from contaminated livestock wastewater.It consisted of two sequential stages:(I)anodic stimulation for p-ASA degradation and(II)reversing electrode polarities for the cathodic reduction of inorganic arsenic.In Stage I,the anode significantly enhanced the degradation of p-ASA,resulting in 18μg/L of As(III)and 700μg/L of As(V)released into the bulk solution.In Stage II,the cathode further reduced the As(III)and As(V)to 8.9 and 35.5μg/L,respectively,through the synergistic action of the cathode and suspended microbes.The inorganic arsenic was recovered as a layer of As(V)-O on the cathode.Microbial analysis indicated that Alcaligenes was responsible for the degradation of p-ASA,while Anaerobacillus and Desulfitibacter played key roles in reducing As(V)and As(III)on the cathode,respectively.This study provided a promising alternative approach for the removal of organoarsenics and in situ recovery of inorganic arsenic from organoarsenic-bearing wastewater.
基金financially supported by the Key projects of National Natural Science Foundation of China(U22A20107)the key projects of the Henan Provincial Science and Technology R&D Program Joint Fund(222301420001)+1 种基金the Distinguished Young Scholars Innovation Team of Zhengzhou University(32320275)Higher Education Teaching Reform Research and Practice Project of Henan Province(2021SJGLX093Y).
文摘High-temperature proton exchange membrane fuel cells(HT-PEMFCs)have the unique advantages of fast electrode reaction kinetics,high CO tolerance,and simple water and thermal management at their operating temperature(120-300℃),which can effectively solve the hydrogen source problem and help achieve the dual-carbon goal.The catalysts in HT-PEMFCs are mainly Pt-based catalysts,which have good catalytic activity in the oxygen reduction reaction(ORR)and hydrogen oxidation reaction(HOR).However,in HT-PEMFCs,the high load of platinum-based catalysts to alleviate the limitation of strong adsorption of phosphoric acid(PA)on the platinum surface on activity expression leads to high cost,insufficient activity,decreased activity under long-term operation and carrier corrosion.The present review mainly summarizes the latest research progress of HT-PEMFCs catalysts,systematically analyzes the application of precious metal and non-precious metal catalysts in HT-PEMFCs,and unveils the structure-activity relationship and anti-PA poisoning mechanism.The current challenges and opportunities faced by HT-PEMFCs are discussed,as well as possible future solutions.It is believed that this review can provide some inspiration for the future development of high-performance HT-PEMFC catalysts.
