采用水热-煅烧法制备了磁性镍铁尖晶石载体NiFe_(2)O_(4),再采用浸渍-还原法在载体上负载Ru纳米粒子制备Ru/NiFe_(2)O_(4)催化剂。采用X射线衍射(XRD)、N2吸附-脱附(BET)、NH3程序升温脱附(NH3-TPD)、H_(2)程序升温还原(H_(2)-TPR)、X...采用水热-煅烧法制备了磁性镍铁尖晶石载体NiFe_(2)O_(4),再采用浸渍-还原法在载体上负载Ru纳米粒子制备Ru/NiFe_(2)O_(4)催化剂。采用X射线衍射(XRD)、N2吸附-脱附(BET)、NH3程序升温脱附(NH3-TPD)、H_(2)程序升温还原(H_(2)-TPR)、X射线光电子能谱(XPS)和电感耦合等离子体发射光谱(ICP-OES)测试对催化剂进行表征分析。结果表明,Ru/NiFe_(2)O_(4)催化剂表面氧物种丰富,相较于载体,负载Ru后催化剂比表面积和表面酸量增加,Ru与载体存在相互作用,这可能是催化剂高活性和高稳定性的关键。将催化剂用于5-羟甲基糠醛(HMF)的选择性氧化,负载Ru后,催化剂催化活性显著提升。对反应条件进行优化,在添加0.08 g KHCO3,氧化剂O2压力为1 MPa,反应温度为80℃,使用0.1 g Ru/NiFe_(2)O_(4)催化剂,在水溶液中反应12 h HMF能完全转化,2,5-呋喃二甲酸(FDCA)产率为98.1%。Ru/NiFe_(2)O_(4)循环使用5次后仍能保持较高的活性,催化剂上活性组分Ru不易浸出,并且催化剂具有磁性能便于与反应溶液分离。为今后工业化催化HMF高效选择性氧化合成FDCA提供参考。展开更多
Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Her...Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Herein,hollow oxygen deficiency-enriched NiFe_(2)O_(4) is synthesized by pyrolytic FeNi bimetallic MOF.The defects of rGO during carbonization can act as nucleation sites for FeNi particles.After nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO.These deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe_(2)O_(4) together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic activity.The resultant NiFe_(2)O_(4)@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^(-2) for OER and 157 mV at 10 mA cm^(-2) for HER in 1 M KOH,respectively.When used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^(-2),respectively.展开更多
4.25Cu-0.75Ni/NiFe2O4 cermets were prepared by doping NiFe2O4 ceramic matrix with the mixed powders of Cu and Ni or Cu-Ni alloy powder as the electrical conducting metallic elements. The effects of technological param...4.25Cu-0.75Ni/NiFe2O4 cermets were prepared by doping NiFe2O4 ceramic matrix with the mixed powders of Cu and Ni or Cu-Ni alloy powder as the electrical conducting metallic elements. The effects of technological parameters, such as the adding modes of metallic elements, the ball milling time, the sintering time and the sintering temperature, on the relative density and resistivity of the cermets were studied. The results show that the resistivity of 4.25Cu-0.75Ni/NiFe2O4 cermets decreases with increasing temperature, and has a turning point at 590℃, which is similar to that of NiFe2O4 ceramic. The sintering temperature and adding modes of metallic elements have a great influence on the properties of 4.25Cu-0.75Ni/NiFe2O4 cermets. When the sintering temperature increases from 1200℃ to 1300℃, the relative density increases from 89.86% to 95.33%, and the resistivity at 960℃ decreases from 0.11Ω·cm to 0.03Ω·cm, respectively. When the metallic elements are added with the mixed powders of Cu and Ni, the cermets of finely and uniformly dispersed metallic phase, high density and electric conductivity are obtained. The relative density and resistivity at 960℃ are 90.23% and 0.04Ω·cm respectively for the cermet samples sintered at 1200℃ for 2h, which are both better than those of the cermets prepared under the same technique conditions but with the metallic elements added as 85Cu-15Ni alloy powders.展开更多
文摘采用水热-煅烧法制备了磁性镍铁尖晶石载体NiFe_(2)O_(4),再采用浸渍-还原法在载体上负载Ru纳米粒子制备Ru/NiFe_(2)O_(4)催化剂。采用X射线衍射(XRD)、N2吸附-脱附(BET)、NH3程序升温脱附(NH3-TPD)、H_(2)程序升温还原(H_(2)-TPR)、X射线光电子能谱(XPS)和电感耦合等离子体发射光谱(ICP-OES)测试对催化剂进行表征分析。结果表明,Ru/NiFe_(2)O_(4)催化剂表面氧物种丰富,相较于载体,负载Ru后催化剂比表面积和表面酸量增加,Ru与载体存在相互作用,这可能是催化剂高活性和高稳定性的关键。将催化剂用于5-羟甲基糠醛(HMF)的选择性氧化,负载Ru后,催化剂催化活性显著提升。对反应条件进行优化,在添加0.08 g KHCO3,氧化剂O2压力为1 MPa,反应温度为80℃,使用0.1 g Ru/NiFe_(2)O_(4)催化剂,在水溶液中反应12 h HMF能完全转化,2,5-呋喃二甲酸(FDCA)产率为98.1%。Ru/NiFe_(2)O_(4)循环使用5次后仍能保持较高的活性,催化剂上活性组分Ru不易浸出,并且催化剂具有磁性能便于与反应溶液分离。为今后工业化催化HMF高效选择性氧化合成FDCA提供参考。
基金financially supported by the National Natural Science Foundation of China(Nos.21878231,21676202 and 51603145)Natural Science Foundation of Tianjin(Nos.19JCZDJC37300 and 17JCZDJC38100)supported by the Science and Technology Plans of Tianjin(Nos.17PTSYJC00040 and 18PTSYJC00180)。
文摘Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Herein,hollow oxygen deficiency-enriched NiFe_(2)O_(4) is synthesized by pyrolytic FeNi bimetallic MOF.The defects of rGO during carbonization can act as nucleation sites for FeNi particles.After nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO.These deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe_(2)O_(4) together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic activity.The resultant NiFe_(2)O_(4)@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^(-2) for OER and 157 mV at 10 mA cm^(-2) for HER in 1 M KOH,respectively.When used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^(-2),respectively.
文摘4.25Cu-0.75Ni/NiFe2O4 cermets were prepared by doping NiFe2O4 ceramic matrix with the mixed powders of Cu and Ni or Cu-Ni alloy powder as the electrical conducting metallic elements. The effects of technological parameters, such as the adding modes of metallic elements, the ball milling time, the sintering time and the sintering temperature, on the relative density and resistivity of the cermets were studied. The results show that the resistivity of 4.25Cu-0.75Ni/NiFe2O4 cermets decreases with increasing temperature, and has a turning point at 590℃, which is similar to that of NiFe2O4 ceramic. The sintering temperature and adding modes of metallic elements have a great influence on the properties of 4.25Cu-0.75Ni/NiFe2O4 cermets. When the sintering temperature increases from 1200℃ to 1300℃, the relative density increases from 89.86% to 95.33%, and the resistivity at 960℃ decreases from 0.11Ω·cm to 0.03Ω·cm, respectively. When the metallic elements are added with the mixed powders of Cu and Ni, the cermets of finely and uniformly dispersed metallic phase, high density and electric conductivity are obtained. The relative density and resistivity at 960℃ are 90.23% and 0.04Ω·cm respectively for the cermet samples sintered at 1200℃ for 2h, which are both better than those of the cermets prepared under the same technique conditions but with the metallic elements added as 85Cu-15Ni alloy powders.
