Synergistic Effect of PtCu Alloy Composition on Catalytic Efficiency in Acidic Alcohol Oxidation Reactions

Precise compositional control of Pt-based alloys is essential for designing efficient and cost-effective electrocatalysts for direct alcohol fuel cells (DAFCs). Here, we report the synthesis of structurally uniform and composition-tunable PtCu alloy nanoclusters via cluster beam deposition using a single magnetron source. By the adjustment of the exposed Pt target area on a custom-designed sputtering ring, the Pt-to-Cu ratio was precisely controlled in a scalable manner. High-resolution electron microscopy confirmed homogeneous, size-tunable alloy clusters, while X-ray photoelectron spectroscopy revealed electron transfer from Cu to Pt, indicating electronic modification upon alloying. Theoretical calculations further support a fully miscible alloy configuration. Electrochemical measurements demonstrated that Cu incorporation significantly enhances the catalytic activity of Pt clusters for both methanol and ethanol oxidation in acidic media while reducing the Pt content. Notably, Pt1Cu1 nanoclusters achieved mass activities 53-fold (methanol oxidation reaction) and 14-fold (ethanol oxidation reaction) higher than commercial Pt/C, with activity exhibiting a volcano-type dependence on alloy composition. These results highlight the critical role of composition-structure tuning in dictating catalytic behavior and establish a general strategy for designing high-performance, resource-efficient bimetallic catalysts for DAFC applications.