防水型氢扩散电极的制备和性质

Preparation and Properties of the Semi-Hydrophobic Hydrogen Diffusion Electrode

用蓝色氧化钨和仲钨酸铵分别制取碳化钨。把碳化钨和聚四氟乙烯乳液、碳黑相混和,加工成防水型氢扩散多孔电极。测定了电极在4mol HCl/(kgH_2O)溶浓中的稳态极化曲线。发现超电位在8mV之间的弱极化区,超电位与总表观电流密度呈线性关系;在阳极极化中等程度的区域,有两条塔费尔直线。电位较高区塔费尔直线的斜率为电位较低区直线斜率的一倍。这结果与气体扩散电极的薄层平板模型理论推论相符合,从而阐明了电极在各电位区内极化的性质。X射线衍射照相证明,制得的碳化钨为α-WC,属六方晶系。

The samples of tungsten carbide were prepared from the blue tungsten trioxide and the ammonium paratungstate Separately. The catalytic layer of the hydrogen diffusion electrode was fabricated by mixing the polytetrafluoroethylene emulsion with WC and pressed under pressure with hydrophobic layer to form the porous electrode. The voltammetric behavior of the electrode in 4mol HCl/(kg H_2O) solution was examined in both anodic and cathodic direction in the weakly polarized region. In the moderately polarized anodic region there were two Tafel regions. The slope of the latter Tafel region was twice the slope of the former. The polarization behaviors of the electrode at various current densities were studied and compared with the results predicted by the theory of the plate-like model of thin layers of the gas diffusion electrode. The prepared WC was identified to be hexagonal crystal of a-WC by X-ray powder diffraction method.