Cu-bipy-BTC衍生碳基材料的制备及其氧还原电催化性能

Preparations and Electrocatalytic Properties of Cu-bipy-BTC-Derived Carbon-Based Catalyst for Oxygen Reduction Reaction

制备高效、廉价的氧还原(ORR)电催化剂是燃料电池的技术关键.本文采用水热法制备出前驱体金属有机骨架化合物(MOF:Cu-bipy-BTC,bipy=2,2′-联吡啶,BTC=均苯三甲酸)后,再高温煅烧得到碳基材料MOF-800.采用扫描电镜、X射线衍射、红外光谱、氮气吸附/脱附等温线和X射线光电子谱表征了材料的形貌和结构特征;采用线性扫描伏安曲线、i-t曲线等考察了材料的氧还原催化性能.结果表明,与前驱体Cu-bipy-BTC相比,MOF-800含有大量的微孔(0.5~1.3 nm),为铜、氮掺杂多孔碳. MOF-800的电荷转移阻抗为10.6Ω,比Cu-bipy-BTC降低了97.2%,具有优良的导电性. MOF-800具有优异的ORR催化性能,其起始电位约为-0.04 V (vs. Ag/AgCl),其电子转移数接近4.铜、氮掺杂的多孔碳结构导电性好,高含量的吡啶氮、吡咯氮和石墨氮提供了大量催化活性位点(CN, Cu-N_x),是MOF-800具有高氧还原电催化性能的主要原因.本研究可为煅烧Cu-bipy-BTC制备碳基材料用于燃料电池修饰阴极提供技术支撑与理论依据.

Efficient and low-cost oxygen reduction reaction(ORR)electrocatalyst plays a key role for fuel cells.In this paper,ORR active metal organic framework(MOF:Cu-bipy-BTC,bipy=2,2′-bipyridine,BTC=1,3,5-tricarboxylate)was prepared using hydrothermal method,and then carbon-based material MOF-800 was obtained from pyrolyzing Cu-bipy-BTC at 800 oC.Scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),nitrogen sorption isotherm and X-ray photolectron spectroscopy(XPS)were used to characterize the morphologies and structures of the catalysts.Linear sweep voltammetry(LSV)and current-time curve(i-t)were adopted to evaluate the electrocatalytic properties of the catalysts.The results showed that the MOF-800 originated a certain amount of micropores(0.5~1.3 nm)compared with the MOF precursor.The MOF-800 had excellent electrical conductivity with a charge transfer resistance of 10.6Ω,reduced by 97.2%compared to Cu-bipy-BTC.It also exhibited excellent ORR electrocatalytic performance with the onset potential of ca.-0.04 V(vs.Ag/AgCl)and the electron transfer number close to 4.As a Cu,N-incorporated carbon-based catalyst,MOF-800 had good electrical conductivity,and the large amounts of pyridinic,pyrrolic and graphitic nitrogen provided abundant active sites(C-N,Cu-N_x),which resulted in the improved ORR electrocatalytic activity.This study provided technical and theoretical validations for the improvements in electrical conductivity and ORR catalytic performance of Cu-bipy-BTC by pyrolyzing.