Preparation and Electrocatalytic Activity of Tungsten Carbide-Montmorillonite Composite

Abstract

The tungsten carbide catalyst is a hot research topic because its catalytic properties are similar to those of platinum. In this paper, a tungsten carbide-montmorillonite (MMT) nanocomposite was fabricated by combining chemical immersion with reduction and carbonization in situ using tungsten hexachloride as the tungsten source and an exfoliated MMT layer as the support. The crystal phase of the sample is composed of monotungsten carbide (WC), bitungsten carbide (W2C), and MMT, and tungsten carbide is distributed on the outer surface of MMT with a granular or lamellar manner. The components of the crystal phase of the sample are related to the reduction and carbonization time during preparation. The microstructure of the sample is related to the ratio of tungsten to MMT in the precursor used to prepare the sample. The electrocatalytic activity of the sample for methanol oxidation was measured by cyclic voltammetry with a three-electrode system in acidic solution. The results show that the electrocatalytic activity of the sample is improved by compositing tungsten carbide on the surface of MMT, and the electrocatalytic activity is similar to that of platinum. After 5 h reduction and carbonization, a precursor with a 4:1 ratio of tungsten to MMT transformed into a sample with 82% and 18% of WC and W2C, respectively (ratio of WC to W2C 4.556). The WC phase forms a uniform loaded layer on the surface of MMT. The electrocatalytic activity of this sample is the highest of the compositions considered. This outline a method to fabricate a tungsten carbide electrocatalyst with similar electrocatalytic activity to platinum.