Reduced Graphene Oxide-supported Tungsten Carbide Modified with Ultralow-Platinum and Ruthenium-loading for Methanol Oxidation

• Reduced graphene oxide-supported tungsten carbide (WC/RGO) was used as support.
• Novel electrocatalyst contains ultra-low noble metals but displays higher activity.
• New approach is established for loading ultra-low bimetallic system on WC/RGO.

Reduced graphene oxide-supported tungsten carbide (WC/RGO) was prepared in a fine structure with nanocrystallites WC fixing on the layers of RGO. Pt and Ru nanoparticles were loaded on WC/RGO sequentially to synthesize electrocatalysts (Pt:Ru)n-WC/RGO via Cu underpotential deposition-redox replacement. Pt and Ru are supposed to present in the form of Pt-adatom and Ru-adatom layer by layer, which leads to a considerably low content of Pt and Ru in the catalysts. A series of electrochemical experiments on different systems, including (Pt:Ru)n-WC/RGO, (Pt)4-WC/RGO, (Pt:Ru)4-RGO and (Pt)4-RGO verified that the increased interaction among Pt, Ru and WC by this method was responsible for the performance enhancement in the (Pt:Ru)4-WC/RGO catalyst for methanol oxidation. The large cathodic shift of the CO stripping peak of the (Pt:Ru)4-WC/RGO catalyst suggests the improved CO tolerance. The optimal Pt/Ru ratio for methanol electro-oxidation was also investigated by controlling deposition amount of Pt and Ru. It was found that the optimal Pt/Ru ratio was 3:2 in our system.