PDF《Ni/NiCo2O4 复合电极的制备及其在碱性介质中的析氧性能》

Ni/NiCo2O4复合电极的制备及其在碱性介质中的析氧性能 鲍晋珍 王森林* (华侨大学材料科学与工程学院应用化学系, 福建 厦门 361021) 摘要: 采用共沉淀法制备尖晶石型复合氧化物 NiCo2O4, 然后将其加入瓦特镀镍液中, 复合电沉积了 Ni/ NiCo2O4复合镀层.

通过改变镀液pH值、 阴极电流密度jk等条件, 探索复合电沉积的最佳工艺条件. 运用扫描电 子显微镜(SEM)、 能谱分析(EDS)和X射线衍射(XRD)表征了复合镀层的表面形貌、 颗粒含量和结构. 结果表 明: 在镀液pH=6.2和jk=100 mA ・ cm-2 的条件下所得Ni/NiCo2O4 复合镀层中, NiCo2O4 的含量达到最高(30.6%, w). 在5 mol ・ L-1 的KOH溶液中, 采用循环伏安、 稳态极化和电化学阻抗法研究了电极的电催化析氧性能. 与镍 电极对比, Ni/NiCo2O4 复合电极的电催化析氧性能更高, 表观活化自由能降低了53.2 kJ ・ mol-1 , 其析氧反应的 表观交换电流密度是镍电极的7倍. 电化学阻抗谱分析表明, Ni/NiCo2O4复合电极在碱性溶液中析氧反应由电 化学步骤和扩散步骤联合控制. 恒电位长时间电解析氧实验表明, 该Ni/NiCo2O4复合电极在碱性溶液中的析氧 具有高的稳定性. 关键词: Ni/NiCo2O4;

尖晶石;

复合电沉积;

析氧电极;

稳定性能 中图分类号: O646 Preparation of the Ni/NiCo2O4 Composite Electrode and Its Properties toward the Oxygen Evolution Reaction in Alkaline Media BAO Jin-Zhen WANG Sen-Lin* (Department of Applied Chemistry, College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, Fujian Province, P. R. China) Abstract: A NiCo2O4 spinel composite oxide was obtained by co-precipitation. A Ni/NiCo2O4 composite coating was prepared by composite electrodeposition in a Ni plating solution by mixing with NiCo2O4 powder. The best plating conditions for the composite electrodeposition were investigated by changing factors such as the plating bath pH and the cathode current density jk. The surface morphology, the NiCo2O4 content, and the structure of the Ni/NiCo2O4 composite coating were characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). As a result, the NiCo2O4 content in the Ni/NiCo2O4 composite coating was found to be the highest (30.6%, w) for a bath pH of 6.2 and a cathodic current density jk of

100 mA・cm-2 . In

5 mol・L-1 KOH solution the electrocatalytic properties toward the oxygen evolution reaction (OER) of the Ni/NiCo2O4 composite electrode was studied using cyclic voltammetry, electrochemical steady-state polarization, and electrochemical impendence spectroscopy (EIS). Compared with the Ni electrode, the electrocatalytic properties for the OER of the Ni/NiCo2O4 composite electrode improved greatly and the apparent activation energy was reduced to 53.2 kJ ・ mol-1 . The apparent exchange current density of the Ni/NiCo2O4 composite electrode toward the OER was

7 times as high as that of a nickel electrode. An electrochemical impendence spectroscopy analysis indicated that the oxygen evolution reaction of the Ni/NiCo2O4 composite electrode was co-controlled by an electrochemical step and a diffusion step. Constant potential electrolysis over extended periods for the OER shows that the stability of the Ni/NiCo2O4 composite electrode is good. [Article] doi: 10.3866/PKU.WHXB20112849 www.whxb.pku.edu.cn 物理化学学报(Wuli Huaxue Xuebao) Acta Phys. -Chim. Sin. 2011,

27 (12), 2849-2856 December Received: June 20, 2011;