碱性介质中高择优取向(220)镍电极上丙醇的电氧化

Electrooxidation of Propanol on Highly Preferred Orientation(220) Nickel Electrode in Alkaline Media

对1．0mol／LNiSO4和0．5mol／LH3BO3体系，控制电位为-1．25V，沉积60min，制得高择优取向镍电极．该镍电极经X射线衍射测定其织构度TC220为92％．采用循环伏安法研究了1mol／LNaOH溶液中高择优取向镍电极上丙醇的电催化氧化机理及活性，结果表明：高择优取向镍电极对正面醇的电催化活性高，对异丙醇的电催化活性小；推导出正丙醇的电氧化动力学方程，运用稳态极化曲线测定了其电氧化过程的动力学参数．Ni（Ⅱ）氧化为Ni（Ⅲ）的反应速度常数K1（E）＝5．25×10－13exp（0．488FE／RT），Ni（Ⅲ）还原为Ni（Ⅱ）的反应速度常数K-1（E）＝2．46×10-4exp（-0．512FE／RT），Ni（Ⅲ）氧化正丙醇的反应速度常数K2＝5．64×10－6L·mol-1s-1．

Ni electrode with (220) highly preferred orientation was obtained with potentio-static electrodeposition in the solution containing 1. 0mol/L NiSO4 and 0. 5 mol/L H3BO3.The Ni electrode deposited at - 1.25 V for 60 min was examined with X-ray diffaction. It was shown that the Ni electrode has a highly preferred orientation with texture degree of 92%. The mechanism and catalytic activities of propanol oxidation on the highly preferred orientation (220) Ni electrode were studied with cyclic voltammetry. It was shown that the electrocatalytic activity of the Ni electrode for propanol oxidation is higher than that for iso-propanol. The kinetic equation of propanol electrooxidation was derived. The kinetic param-eters were measured with polarization curves- The rate constant [K1, (E)] for the oxidation of Ni(Ⅱ) to Ni(Ⅲ) is 5. 25×10-13exp(0. 488FE/RT), The rate constant [k-1(E)j]for the re-duction of Ni(Ⅲ) to Ni(Ⅲ) is 2. 46×10-4exp(-0.512FE/RT) and the rate constant (k2)for the oxidation of propanol by Ni(Ⅲ) is 5. 64×10-6 L. mol-1s-1.