Effect of surface carbon on the hydrogen evolution reactivity of tungsten carbide (WC) and Pt-modified WC electrocatalysts

Tungsten carbide (WC) has been previously identified as both an electrocatalyst and a support for several types of electrochemical reactions. The synthesis of WC often leads to excess surface carbon that can greatly affect its electrocatalytic activity. This work will evaluate the effect of surface carbon on WC both as a catalyst and as a support for monolayer (ML) amounts of platinum (Pt). WC thin films with no surface carbon, along with those with 1, 2, 3, or 4 equivalent ML of surface carbon, were synthesized. The hydrogen evolution reaction (HER) activity was used as a probe to test the effect of surface carbon on the electrochemical activity of WC and 1 ML Pt on WC (Pt/WC) using linear sweep voltammogram (LSV) in 0.5 M sulfuric acid. The HER activity of WC was relatively unaffected for very small amounts of surface carbon but decreased when several MLs or more of surface carbon was present. Pt/WC without surface carbon was found to have slightly higher HER activity as compared to Pt deposited on WC with surface carbon.

► The effect of surface carbon was investigated on phase-pure WC as a catalyst and a support. ► WC films with 0, 1, 2, 3 and 4 ML of graphitic-like surface carbon were synthesized and characterized. ► HER activity of WC and Pt/WC was affected by the presence of surface carbon.