碱性燃料电池Co-N/C复合催化剂的电化学性能

碳黑经过酸处理后再加入醋酸钴经氨气900 ℃热处理后, 以其制备的气体扩散电极在6 mol•L^―1 KOH溶液中对氧还原反应(ORR)的电催化性能得到大大提高. XRD物相分析表明: 碳粉中加入醋酸钴经氨气热处理生成了氮化钴(Co_5.47N). 通过极化曲线和交流阻抗方法对制备的气体扩散电极在空气中的性能进行了研究. 室温时在－0.2 V (vs. Hg/HgO)电位下, 未经处理的碳电极对氧还原基本没有电流产生; 用酸处理后的碳电极在空气中的电流密度提高到57 mA•cm^―2; 而Co-N/C复合电极在同样条件下电流密度可达170 mA•cm^―2, 交流阻抗显示氮化物的生成减小了氧还原反应的阻抗, 增强了对氧还原反应的电催化作用.

Electrochemical Performance of Co-N/C Complex Catalyst for Alkaline Fuel Cell

After acid-treatment and addition of cobalt acetate followed by heat-treatment via ammonia gas at 900 ℃, the carbon black was produced into a gas diffusion electrode and its electro-catalytic performance for oxygen reduction improved greatly in 6 mol•L^－1 KOH electrolyte. The phase and structure of the produced sample were analyzed by X-ray diffraction and cobalt nitride (Co_5.47N) generated by adding cobalt acetate followed by heat-treatment with ammonia gas. The performance of gas diffusion electrodes for oxygen reduction reaction (ORR) in air was studied by polarization curves and AC impedance. At room temperature, the carbon electrode had no effect on ORR. After the carbon black was treated by acid, the current density for ORR in air achieved 57 mA•cm^－2 at potential of －0.2 V versus a Hg/HgO reference electrode. While the current density of 170 mA•cm^－2 of the Co-N/C complex electrode could be achieved in the same condition. AC impedance shows that because of the generation of cobalt nitride, the impedance of oxygen reduction greatly reduced, which was in favor of oxygen reduction. And the chronoamperometric curves indicate that the Co-N/C complex electrode exhibits high catalytic activity and stability.