Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first ti...Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first time,a Mn-N-C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy.The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation.Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix,the catalyst exhibits excellent activity for NRR with high activity and selectivity,achieving a high Faradaic efficiency of 32.02%for ammonia synthesis at−0.45 V versus reversible hydrogen electrode.Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N_(2) adsorption,activation and selective reduction to NH_(3) by the distal mechanism.This work provides a simple synthesis process for Mn-N-C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites.展开更多
Based on the survey and research of awareness,preferences and purchasing behavior of residents about Korean food and agricultural products in Beijing,Shanghai,Shenyang,Qingdao and Chongqing in 2014,this paper makes a ...Based on the survey and research of awareness,preferences and purchasing behavior of residents about Korean food and agricultural products in Beijing,Shanghai,Shenyang,Qingdao and Chongqing in 2014,this paper makes a statistical analysis of the influence of consumers' personal characteristics,awareness,buying habits and income on Chinese consumers' identification and purchase of Korean food and agricultural products,and performs an empirical analysis on the purchasing behavior using Tobit model. The results show that consumers' personal characteristics have no significant influence on the purchase of Korean food; consumers' income levels have a significant positive effect on the purchasing amount of Korean food; consumers' location has a significant effect on the purchasing amount; consumers' recognition has a positive effect on consumers' purchasing behavior,but it is not significant.展开更多
N-alkylation of sulfosalicylic acid-doped polyaniline(PANI-SSA)was used to promote the anticorrosion performance of PANI-SSA/epoxy coating for 5083 Al alloy.PANI-SSA was modified with C5H11Br and C12H25Br in polar sol...N-alkylation of sulfosalicylic acid-doped polyaniline(PANI-SSA)was used to promote the anticorrosion performance of PANI-SSA/epoxy coating for 5083 Al alloy.PANI-SSA was modified with C5H11Br and C12H25Br in polar solvents IPA(isopropanol)and DMF(dimethylformamide),and then characterized by FTIR,XPS and sedimentation experiments.Results showed that alkanes were successfully linked onto the PANI-SSA chains.The compatibility between N-alkylated PANI-SSA and epoxy/xylene solution was improved.SEM results proved a better dispersion performance of N-alkylated PANI-SSA in epoxy coatings,with less holes and aggregations.Corrosion protection of the epoxy coatings incorporating PANI-SSA and N-alkylated PANI-SSA on 5083 Al alloy was studied by EIS and adhesion measurements in 3.5%NaCl solution.It turned out that the epoxy coating including C12H25Br-modified PANI-SSA in DMF has yielded the highest values of impedance modulus and best protective properties.展开更多
A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy(WEP)composite coatings.The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing su...A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy(WEP)composite coatings.The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants,cetyl trimethyl ammonium bromide(CTAB)and sodium dodecyl sulfate(SDS).The nanosheets containing solution thus formed are subjected to a quick dialysis and then directly used as a diluent for WEP without any further treatment.This preparation method overcomes the commonly identified problems of aggregations and‘corrosion promotion’effect associated with graphene,and increases the impedance of the composite coatings by more than two orders of magnitude.The analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition capabilities.The strategy reported herein may pave the path to the large-scale production of graphene anticorrosion coatings.展开更多
基金The authors thank the financial support from the National Natural Science Foundation of China(No.51902204,52001214,21975163)Bureau of Industry and Information Technology of Shenzhen(No.201901171518)Shenzhen Science and Technology Program(KQTD20190929173914967).
文摘Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first time,a Mn-N-C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy.The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation.Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix,the catalyst exhibits excellent activity for NRR with high activity and selectivity,achieving a high Faradaic efficiency of 32.02%for ammonia synthesis at−0.45 V versus reversible hydrogen electrode.Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N_(2) adsorption,activation and selective reduction to NH_(3) by the distal mechanism.This work provides a simple synthesis process for Mn-N-C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites.
基金Supported by Research Project of Korea Rural Economic Research Institute in 2014
文摘Based on the survey and research of awareness,preferences and purchasing behavior of residents about Korean food and agricultural products in Beijing,Shanghai,Shenyang,Qingdao and Chongqing in 2014,this paper makes a statistical analysis of the influence of consumers' personal characteristics,awareness,buying habits and income on Chinese consumers' identification and purchase of Korean food and agricultural products,and performs an empirical analysis on the purchasing behavior using Tobit model. The results show that consumers' personal characteristics have no significant influence on the purchase of Korean food; consumers' income levels have a significant positive effect on the purchasing amount of Korean food; consumers' location has a significant effect on the purchasing amount; consumers' recognition has a positive effect on consumers' purchasing behavior,but it is not significant.
基金financially supported by the National Natural Science Foundation of China(Nos.51622106 and 51871049).
文摘N-alkylation of sulfosalicylic acid-doped polyaniline(PANI-SSA)was used to promote the anticorrosion performance of PANI-SSA/epoxy coating for 5083 Al alloy.PANI-SSA was modified with C5H11Br and C12H25Br in polar solvents IPA(isopropanol)and DMF(dimethylformamide),and then characterized by FTIR,XPS and sedimentation experiments.Results showed that alkanes were successfully linked onto the PANI-SSA chains.The compatibility between N-alkylated PANI-SSA and epoxy/xylene solution was improved.SEM results proved a better dispersion performance of N-alkylated PANI-SSA in epoxy coatings,with less holes and aggregations.Corrosion protection of the epoxy coatings incorporating PANI-SSA and N-alkylated PANI-SSA on 5083 Al alloy was studied by EIS and adhesion measurements in 3.5%NaCl solution.It turned out that the epoxy coating including C12H25Br-modified PANI-SSA in DMF has yielded the highest values of impedance modulus and best protective properties.
基金financially supported by the National Natural Science Foundation of China(Nos.52001214 and 51902204)the China Postdoctoral Science Foundation(No.2020M672796)+2 种基金the Bureau of Industry and Information Technology of Shenzhen(No.201901171518)the Shenzhen Science and Technology Program(No.JSGG20191129141016881)the technical support provided by Instrumental Analysis Center of Shenzhen University(Xili Campus)and the Shiyanjia lab(www.shiyanjia.com)。
文摘A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy(WEP)composite coatings.The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants,cetyl trimethyl ammonium bromide(CTAB)and sodium dodecyl sulfate(SDS).The nanosheets containing solution thus formed are subjected to a quick dialysis and then directly used as a diluent for WEP without any further treatment.This preparation method overcomes the commonly identified problems of aggregations and‘corrosion promotion’effect associated with graphene,and increases the impedance of the composite coatings by more than two orders of magnitude.The analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition capabilities.The strategy reported herein may pave the path to the large-scale production of graphene anticorrosion coatings.
