CoSeO_3化合物的制备及对阴极氧还原的催化性能

Synthesis and Performance of CoSeO_3 Compound as a Cathodic Catalyst for Oxygen Reduction

以Co4（CO）12和Se为原料,采用低温回流方法在乙二醇介质中合成了CoSeO3化合物。利用扫描电镜（SEM）、X射线衍射仪（XRD）和旋转圆盘电极（RDE）技术表征合成的化合物微观形貌、结构特征和电化学性能。这种化合物主要由单斜结构的CoSeO3 H2O晶粒组成,粒径大小约为26.7 nm,具有规则的晶体外形。在25℃,0.5 mol/L H2SO4电解液中,CoSeO3化合物对氧还原反应（ORR）表现出明显的电催化活性,开路电位为0.80 V（vs NHE）。根据Koutecky-Levich方程计算出每个氧分子还原过程转移的电子数约为3.8。在0.64~0.76 V（vs NHE）电位范围内,测得催化剂的传递系数、Tafel斜率和交换电流密度分别为0.50、119 mV和1.98×10-6mA/cm2。

Novel CoSeO3 nanoparticles were successfully synthesized by low temperature refluxing method using dodecacarbonyltetracobalt [Co4（CO）12] and selenium （Se） as raw materials in glycol solvent. The crystalline structure, morphology and electrochemical performances of the as-prepared product were characterized by scanning electron microscope （SEM）, X-ray diffraction （XRD） and rotating disk electrode （RDE） technique. Results show that the as-obtained CoSeO3 compound presents the structural characteristics of monoclinic CoSeO3·H20 with the particle size of 26.7 nm and regular figure. The catalyst demonstrates significant electrocatalytic activity towards oxygen reduction reaction （ORR）, showing an open circuit potential （OCP） of 0.80 V （vs NHE） in 0.5 mol/L H2SO4 solution at 25℃. The transfer process of about 3.8 electrons is determined during the reduction per oxygen molecule by using Koutecky-Levich equation. The transfer coefficient, Tafel slope and exchange current density are 0.50, 119 mV and 1.98 × 10^（-6） mA/cm^2 in the potential region of 0.64-0.76 V （vs NHE）, respectively. The catalytic activity and electro- chemical stability of the catalyst are compared with a commercial Pt catalyst.