Promoting the methanol oxidation catalytic activity by introducing surface nickel on platinum nanoparticles

Abstract

High performance methanol oxidation reaction (MOR) catalysts are critical to the performance of attractive, direct methanol fuel cells. Here, we use surface controlled PtNi alloy nanoparticles as model catalysts to study the MOR mechanism and give further guidance to the design of new high performance MOR catalysts. The enhanced MOR activity of PtNi alloy was mainly attributed to the enhanced OH adsorption owing to surface Ni sites. This suggests that the MOR undergoes the Langmuir–Hinshelwood mechanism, whereby adsorbed CO is removed with the assistance of adsorbed OH. Within the PtNi catalyst, Pt provides methanol adsorption sites (in which methanol is converted to adsorbed CO) and Ni provides OH adsorption sites. The optimized Pt–Ni ratio for MOR was found to be 1:1. This suggests that bifunctional catalysts with both CO and OH adsorption sites can lead to highly active MOR catalysts.