The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles

The catalytic activity of WC/Pt electrocatalysts towards hydrogen oxidation reaction (HOR) in acid solution was studied. Tungsten carbide (WC) prepared by polycondensation of resorcinol and formaldehyde in the presence of ammonium metatungstate salt and CTABr surfactant was used as the support of a Pt electrocatalyst (WC/Pt). The obtained WC/Pt electrodes were characterized by XRD, HRTEM, EDS, EELS and electrochemical measurements. HRTEM analysis showed that the WC particles possess a core–shell structure with a metallic tungsten core and a shell composed of a mixture of tungsten carbides shell (WC and W2C). The WC/Pt catalyst is composed of well-dispersed sub-nanometer Pt clusters which consist of a few to several tens of Pt atoms. EELS measurements indicate that the WC particles function as nucleation sites for Pt nanoparticles. Based on the Tafel–Heyrovsky–Volmer mechanism the corresponding kinetic equations were derived to describe the HOR current–potential behavior over the entire potential region on RDE. The fitting showed that in the lower potential region HOR on Pt proceeds most likely via the Tafel–Volmer (TV) pathway. The kinetic results also showed that the WC/Pt(1%) when compared to the standard C/Pt(1%) electrode led to a remarkable enhancement of the hydrogen oxidation in an acidic medium, which was explained by H-spill-over between platinum and tungsten carbide.