Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they ...Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they still face challenges pertaining of poor stability and low activity,which hinder their further application.Herein,we present a Cu_(2)O/Cu heterojunction catalyst supported on nitrogen-doped porous carbon for nitrate reduction.High resolution transmission electron microscopy(HRTEM)and X-ray Diffraction(XRD)results confirm the presence of Cu_(2)O/Cu heterojunctions,which serve as an active phase in catalysis.The nitrogen-doped porous carbon as a carrier not only enhances the catalyst’s stability,but also facilitates the exposure and dispersion of active sites.At-1.29 V(vs.RHE),the maximum production rate of ammonia reaches 8.8 mg/(mg·h)with a Faradaic efficiency of 92.8%.This study also elucidates the effect of Cu_(2)O-to-Cu ratio in the heterojunction on catalytic performance,thereby providing valuable insights for designing efficient nitrate reduction catalysts for ammonia production.展开更多
The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalyti...The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalytic nitrate reduction reaction(eNO_(3)RR)has been widely studied for its advantages of being eco-friendly,easy to operate,and controllable under environmental conditions with renewable energy as the driving force.Transition metal-based catalysts(TMCs)have been widely used in electrocatalysis due to their abundant reserves,low costs,easy-to-regulate electronic structure and considerable electrochemical activity.In addition,TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction,the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity.Based on this,this review firstly discusses the mechanism as well as analyzes the two main reduction products(N_(2)and NH_(3))of eNO_(3)RR,and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism.Secondly,this review mainly focuses on the recent advances in the direction of eNO_(3RR)with four types of TMCs,Fe,Co,Ni and Cu,and unveils the interfacial modulation strategies of Fe,Co,Ni and Cu catalysts for the activity,reaction pathway and stability.Finally,reasonable suggestions and opportunities are proposed for the challenges and future development of eNO_(3)RR.This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts(NMCs)for eNO_(3)RR.展开更多
A pot experiment was conducted to study the influences of foliar application of glycine,alanine,lysine,and glutamic acid in 200 mg/kg or 500 mg/kg upon the quality and enzyme activity of flowering Chinese cabbage（Bra...A pot experiment was conducted to study the influences of foliar application of glycine,alanine,lysine,and glutamic acid in 200 mg/kg or 500 mg/kg upon the quality and enzyme activity of flowering Chinese cabbage（Brassica parachinensis Bailey）.The results showed that all the application of these four amino acids could increase the yield of flowering Chinese cabbage,significantly raise the content of soluble sugar,and reduce the accumulation of nitrate.The applications of three other amino acids except alanine can increase the content of soluble proteins and decrease the accumulation of oxalic acid.However,the application of amino acid has insignificant influences on the SPAD number of chlorophyll,and causes the decrease of Vitamin C content.Meanwhile,the application of amino acid can improve the activity of nitrate reductase（NR） and glutamate dehydrogenase（GDH） as well.It shows that the application of amino acid is beneficial to improve ammonia metabolism,reduce the accumulation of nitrate and oxalic acid,increase the content of soluble sugar and soluble proteins,and improve the quality of flowering Chinese cabbage.展开更多
This study aimed to survey the expression of genes involved in rice N uptake and aasimilatory network and to understand the potential molecular mechanisms responsible for the NO3^-enhanced NH4^＋ uptake. By using quan...This study aimed to survey the expression of genes involved in rice N uptake and aasimilatory network and to understand the potential molecular mechanisms responsible for the NO3^-enhanced NH4^＋ uptake. By using quantitative real-time polymerase chain reaction （PCR）, the genes related to N nutrition, including ammonium transporters （AMTs） and ammonium assimilatory enzymes （GS and GOGAT）, were transcriptionally analyzed in rice plants grown in the absence and presence of NO4^- in the NH4^＋-containing medium. The results showed that NH4^＋ uptake by rice was enhanced by the NO3^- supply to the medium. At the same time and in parallel, the amount of transcripts of seven genes （OsAMT1;1, OsAMT1;2, OsAMT4;1, OsGLNP, OsGLU1, OsGLT1, and OsGLTP） was increased in rice roots, but the expression of two genes （OsGLN1;1 and OsGLN1;P） was decreased and that of OsAMT1;3 remained without change. Up- or downregulation of these genes involved in NH4^＋ uptake and assimilation correlated with the increase in NH4^＋ uptake in the presence of NO3^- in rice roots.展开更多
A hydroponic experiment was carried out to determine the influence of replacing 20% of nitrate-N in nutrient solutions with 20 individual amino acids on growth, nitrate accumulation, and concentrations of nitrogen （N...A hydroponic experiment was carried out to determine the influence of replacing 20% of nitrate-N in nutrient solutions with 20 individual amino acids on growth, nitrate accumulation, and concentrations of nitrogen （N）, phosphorus （P）, and potassium （K） in pak-choi （Brassica chinensis L.） shoots. When 20% of nitrate-N was replaced with arginine （Arg） compared to the full nitrate treatment, pak-choi shoot fresh and dry weights increased significantly （P ≤ 0.05）, but when 20% of nitrate-N was replaced with alanine （Ala）, valine （Val）, leucine （Leu）, isoleucine （Ile）, proline （Pro）, phenylalanine （Phe）, methionine （Met）, aspartic acid （Asp）, glutamic acid （Glu）, lysine （Lys）, glycine （Gly）, serine （Ser）, threonine （Thr）, cysteine （Cys）, and tyrosine （Tyr）, shoot fresh and dry weights decreased significantly （P ≤ 0.05）. After replacing 20% of nitrate-N with asparagine （Asn） and glutamine （Gin）, shoot fresh and dry weights were unaffected. Compared to the full nitrate treatment, amino acid replacement treatments, except for Cys, Gly, histidine （His）, and Arg, significantly reduced （P ≤0.05） nitrate concentrations in plant shoots. Except for Cys, Leu, Pro, and Met, total N concentrations in plant tissues of the other amino acid treatments significantly increased （P ≤ 0.05）. Amino acids also affected total P and K concentrations, but the effects differed depending on individual amino acids. To improve pak-choi shoot quality, Gln and Asn, due to their insignificant effects on pak-choi growth, their significant reduction in nitrate concentrations, and their increase in macroelement content in plants, may be used to partially replace nitrate-N.展开更多
A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal...A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal structure was determined by X-ray diffraction method. The complex crystallizes in monoclinic, space group P21/n with a = 9.913(4), b = 19.057(8), c = 10.169(4) ? b = 114.292(7), V = 1751(1) 3, C26H38Cu2N8O14, Mr = 813.72, Dc = 1.543 g/cm3, m(MoKa) = 1.290 mm-1, F(000) = 840, Z = 2, the final R = 0.0398 and wR = 0.0986 for 1878 observed reflections (I>2s(I)). The imino nitroxide 2-(2-pyridyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl (im2-py) is reduced in the reaction to yield Him2-py which consists of oxalato-bridged centrosymmetric [Cu2(m-C2O4)(Him2-py)2(H2O)2]2+ ions and noncoordinated NO3- anions. Each copper(II) ion is in a distorted tetragonal pyramid environment: two nitrogen atoms from Him2-py and two oxygen atoms from the oxalate group are in the basal plane, and one water molecule at the axial position.展开更多
An industrial electrolytic cell was designed for the electrochemical synthesis of N-methylhydroxylamine hydrochloride （N-MHA）. Copper was used as the cathode, graphite as the anode, and a cation membrane as the sepa...An industrial electrolytic cell was designed for the electrochemical synthesis of N-methylhydroxylamine hydrochloride （N-MHA）. Copper was used as the cathode, graphite as the anode, and a cation membrane as the separator. The results show that N-MHA with a high purity of 99% can be electrosynthesized directly from nitromethane in HC1 solution. Under a constant current of 1000-2500A.m^-2 in the temperature of 30-50℃, the average yield, current efficiency, and reaction selectivity were 65%, 70%, and 99%, respectively. Graphite electrode and membrane material can be used continuously in the preparative electrolysis for 5000h. Moreover, the effects of the electrode and membrane materials, current intensity, electrolyte temperature, and other associated parameters on the electrosynthesis results were investigated. The direct current power consumption was 8151.3kW-h-（1000kg N-MHA）^ -1. This method is a simple separation process with limited contamination and hence, is a new green synthesis method for the industrial production of N-MHA.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(DUT22LAB601)the Technology Development Contract of Sinopec(123038).
文摘Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they still face challenges pertaining of poor stability and low activity,which hinder their further application.Herein,we present a Cu_(2)O/Cu heterojunction catalyst supported on nitrogen-doped porous carbon for nitrate reduction.High resolution transmission electron microscopy(HRTEM)and X-ray Diffraction(XRD)results confirm the presence of Cu_(2)O/Cu heterojunctions,which serve as an active phase in catalysis.The nitrogen-doped porous carbon as a carrier not only enhances the catalyst’s stability,but also facilitates the exposure and dispersion of active sites.At-1.29 V(vs.RHE),the maximum production rate of ammonia reaches 8.8 mg/(mg·h)with a Faradaic efficiency of 92.8%.This study also elucidates the effect of Cu_(2)O-to-Cu ratio in the heterojunction on catalytic performance,thereby providing valuable insights for designing efficient nitrate reduction catalysts for ammonia production.
基金National Natural Science Foundation of China(Nos.52172291 and 52122312)“Dawn”Program of Shanghai Education Commission,China(No.22SG31)。
文摘The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalytic nitrate reduction reaction(eNO_(3)RR)has been widely studied for its advantages of being eco-friendly,easy to operate,and controllable under environmental conditions with renewable energy as the driving force.Transition metal-based catalysts(TMCs)have been widely used in electrocatalysis due to their abundant reserves,low costs,easy-to-regulate electronic structure and considerable electrochemical activity.In addition,TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction,the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity.Based on this,this review firstly discusses the mechanism as well as analyzes the two main reduction products(N_(2)and NH_(3))of eNO_(3)RR,and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism.Secondly,this review mainly focuses on the recent advances in the direction of eNO_(3RR)with four types of TMCs,Fe,Co,Ni and Cu,and unveils the interfacial modulation strategies of Fe,Co,Ni and Cu catalysts for the activity,reaction pathway and stability.Finally,reasonable suggestions and opportunities are proposed for the challenges and future development of eNO_(3)RR.This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts(NMCs)for eNO_(3)RR.
基金Supported by National Scientific and Technological Supporting Project(2008BADA4B04-09)Guangdong Province Scientific and Technological Project(2008A020100017)Guangdong Province Department of Finance Project[(2006)143]~~
文摘A pot experiment was conducted to study the influences of foliar application of glycine,alanine,lysine,and glutamic acid in 200 mg/kg or 500 mg/kg upon the quality and enzyme activity of flowering Chinese cabbage（Brassica parachinensis Bailey）.The results showed that all the application of these four amino acids could increase the yield of flowering Chinese cabbage,significantly raise the content of soluble sugar,and reduce the accumulation of nitrate.The applications of three other amino acids except alanine can increase the content of soluble proteins and decrease the accumulation of oxalic acid.However,the application of amino acid has insignificant influences on the SPAD number of chlorophyll,and causes the decrease of Vitamin C content.Meanwhile,the application of amino acid can improve the activity of nitrate reductase（NR） and glutamate dehydrogenase（GDH） as well.It shows that the application of amino acid is beneficial to improve ammonia metabolism,reduce the accumulation of nitrate and oxalic acid,increase the content of soluble sugar and soluble proteins,and improve the quality of flowering Chinese cabbage.
基金Project supported by the National Natural Science Foundation of China (No.30390083).
文摘This study aimed to survey the expression of genes involved in rice N uptake and aasimilatory network and to understand the potential molecular mechanisms responsible for the NO3^-enhanced NH4^＋ uptake. By using quantitative real-time polymerase chain reaction （PCR）, the genes related to N nutrition, including ammonium transporters （AMTs） and ammonium assimilatory enzymes （GS and GOGAT）, were transcriptionally analyzed in rice plants grown in the absence and presence of NO4^- in the NH4^＋-containing medium. The results showed that NH4^＋ uptake by rice was enhanced by the NO3^- supply to the medium. At the same time and in parallel, the amount of transcripts of seven genes （OsAMT1;1, OsAMT1;2, OsAMT4;1, OsGLNP, OsGLU1, OsGLT1, and OsGLTP） was increased in rice roots, but the expression of two genes （OsGLN1;1 and OsGLN1;P） was decreased and that of OsAMT1;3 remained without change. Up- or downregulation of these genes involved in NH4^＋ uptake and assimilation correlated with the increase in NH4^＋ uptake in the presence of NO3^- in rice roots.
基金Project supported by the National Natural Science Foundation of China (No.30370838).
文摘A hydroponic experiment was carried out to determine the influence of replacing 20% of nitrate-N in nutrient solutions with 20 individual amino acids on growth, nitrate accumulation, and concentrations of nitrogen （N）, phosphorus （P）, and potassium （K） in pak-choi （Brassica chinensis L.） shoots. When 20% of nitrate-N was replaced with arginine （Arg） compared to the full nitrate treatment, pak-choi shoot fresh and dry weights increased significantly （P ≤ 0.05）, but when 20% of nitrate-N was replaced with alanine （Ala）, valine （Val）, leucine （Leu）, isoleucine （Ile）, proline （Pro）, phenylalanine （Phe）, methionine （Met）, aspartic acid （Asp）, glutamic acid （Glu）, lysine （Lys）, glycine （Gly）, serine （Ser）, threonine （Thr）, cysteine （Cys）, and tyrosine （Tyr）, shoot fresh and dry weights decreased significantly （P ≤ 0.05）. After replacing 20% of nitrate-N with asparagine （Asn） and glutamine （Gin）, shoot fresh and dry weights were unaffected. Compared to the full nitrate treatment, amino acid replacement treatments, except for Cys, Gly, histidine （His）, and Arg, significantly reduced （P ≤0.05） nitrate concentrations in plant shoots. Except for Cys, Leu, Pro, and Met, total N concentrations in plant tissues of the other amino acid treatments significantly increased （P ≤ 0.05）. Amino acids also affected total P and K concentrations, but the effects differed depending on individual amino acids. To improve pak-choi shoot quality, Gln and Asn, due to their insignificant effects on pak-choi growth, their significant reduction in nitrate concentrations, and their increase in macroelement content in plants, may be used to partially replace nitrate-N.
基金This work was supported by the National Natural Science Foundation of China (No. 20271029)
文摘A new dicopper(II) compound with oxalate and reduced imino nitroxide radicals [Cu2(m-C2O4)(Him2-py)2(H2O)2](NO3)2 (Him2-py=1-hydroxy-2-(2-pyridyl)-4,4,5,5-tetramethyli- midazoline) has been synthesized and its crystal structure was determined by X-ray diffraction method. The complex crystallizes in monoclinic, space group P21/n with a = 9.913(4), b = 19.057(8), c = 10.169(4) ? b = 114.292(7), V = 1751(1) 3, C26H38Cu2N8O14, Mr = 813.72, Dc = 1.543 g/cm3, m(MoKa) = 1.290 mm-1, F(000) = 840, Z = 2, the final R = 0.0398 and wR = 0.0986 for 1878 observed reflections (I>2s(I)). The imino nitroxide 2-(2-pyridyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl (im2-py) is reduced in the reaction to yield Him2-py which consists of oxalato-bridged centrosymmetric [Cu2(m-C2O4)(Him2-py)2(H2O)2]2+ ions and noncoordinated NO3- anions. Each copper(II) ion is in a distorted tetragonal pyramid environment: two nitrogen atoms from Him2-py and two oxygen atoms from the oxalate group are in the basal plane, and one water molecule at the axial position.
文摘An industrial electrolytic cell was designed for the electrochemical synthesis of N-methylhydroxylamine hydrochloride （N-MHA）. Copper was used as the cathode, graphite as the anode, and a cation membrane as the separator. The results show that N-MHA with a high purity of 99% can be electrosynthesized directly from nitromethane in HC1 solution. Under a constant current of 1000-2500A.m^-2 in the temperature of 30-50℃, the average yield, current efficiency, and reaction selectivity were 65%, 70%, and 99%, respectively. Graphite electrode and membrane material can be used continuously in the preparative electrolysis for 5000h. Moreover, the effects of the electrode and membrane materials, current intensity, electrolyte temperature, and other associated parameters on the electrosynthesis results were investigated. The direct current power consumption was 8151.3kW-h-（1000kg N-MHA）^ -1. This method is a simple separation process with limited contamination and hence, is a new green synthesis method for the industrial production of N-MHA.
