碳化钨纳米晶薄膜电极在对硝基苯酚电化学还原中的催化性能

采用磁控溅射物理气相沉积和等离子体增强化学气相沉积技术,在金属镍基体上制备具有纳米晶结构的碳化钨薄膜;采用循环伏安、准稳态极化和恒电位阶跃等电化学方法研究了对硝基苯酚(PNP)在碳化钨纳米晶薄膜电极上电化学还原的特性和机理.研究表明,采用磁控溅射物理气相沉积技术制备得到的薄膜是由直径为20nm的WC1-X构成,在这种薄膜电极上,PNP电化学还原在电位为(0.95V(Vs. SCE)时,出现一个电流密度为6.0mA(cm(2还原峰,还原反应的表观活化能为12.0kJ(mol(1;而采用等离子体增强化学气相沉积技术制备得到的薄膜是由直径为35nm的纯相WC构成,PNP在该薄膜电极上电化学还原峰电位为(1.05 V(Vs. SCE),还原电流达10.0 mA(cm(2,表观活化能为10.9 kJ(mol(1. PNP在这两种碳化钨薄膜电极上都经过两步不可逆的电化学反应还原成对氨基苯酚,控制步骤为电极反应的电荷传递过程.

Electrocatalytic Properties of Nanocrystalline Tungsten Carbide Thin Film as Cathode Electrode for p-nitrophenol Electro-reduction

The nano-crystalline tungsten carbide thin films were deposited on Ni substrate by the method of plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering physical vapor deposition(MSPVD) respectively. Electrocatalytic properties and reaction mechanism of p-nitrophenol electroreduction on nano-crystalline tungsten carbide thin film electrode was investigated by cyclic voltammetry, quasi-stable state polarization and potentiostatic phase step methods. The results indicate that the main component of the MSPVD-WC is WC1-x with uniform grains of diameter about 20 nm. Current peak of 6.0mA?cm?2 during p-nitrophenol electroreduction appeares at ?0.95V(Vs.SCE) and the activation energy is 12.0 kJ?mol?1. For PECVD-WC, the main component is pure WC with diameter 35nm, electro-reduction current peak is 10.0 mA?cm?2 observed at potential ?1.05V(Vs.SCE), the activation energy is 10.9 kJ?mol?1. p-Nitrophenol is reduced to p-aminophenol after two irreversible electrochemical reaction on these thin film electrodes. The control step of p-nitrophenol eleroreduction on WC thin film electrode is electron exchange process.