Ru-specific promotion in electrodeposited Pt-based bimetallic catalysts for isopropanol electrooxidation

Abstract

Isopropanol/acetone is a promising electroactive liquid organic hydrogen carrier pair due to its high hydrogen storage capacity (3.4 wt%), low toxicity, and large-scale availability. The slow electrocatalytic oxidation of isopropanol is the bottleneck for the isopropanol/acetone pair's energy-storage applications. Platinum-based catalysts have shown distinguished catalytic activity in this reaction but suffer from catalyst poisoning and performance degradation. Second-metal doping, especially ruthenium, is considered a common strategy to enhance catalytic performance. To clarify whether the enhancement originates from a general bimetallic effect or a ruthenium-specific promotion, this study prepared platinum–ruthenium and platinum–rhodium catalysts with varying metal ratios via electrodeposition and evaluated them for isopropanol electrooxidation. Electrochemical analysis reveals that ruthenium doping is superior to rhodium doping, and that a 1 : 1 atomic ratio is optimal. Kinetic and thermodynamic investigations reveal that both alterations in the electronic structure and ruthenium-specific oxygen affinity contribute to the enhanced efficiency and stability of bimetallic catalysts in the oxidation of isopropanol, with the latter being more pronounced.