Preparations and Electrocatalytic Properties of Cu-bipy-BTC-Derived Carbon-Based Catalyst for Oxygen Reduction Reaction
- 2019年第25卷 
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10.6 Ω，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(C-N, Cu-Nx)，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 °C. 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 10.6 Ω, 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–Nx), 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.