Solid-solution surface alloying of Cu nanocubes with platinum-group metals: pathway switching and catalyst stabilization in CO2 reduction

Abstract

Precise control over morphology and alloy configuration is essential for addressing complex reactions, such as the electrochemical CO₂ reduction reaction (CO₂RR), which proceeds through multiple intermediates and requires enhanced selectivity, activity and stability. However, achieving simultaneous regulation of these two structural features remains a formidable challenge. Here we report novel shape-controlled Cu-based solid-solution surface-alloy nanocrystals composed of Cu nanocube (NC) cores surrounded by atomically alloyed platinum-group metal shells (Cu/Cu_1−xM_x NCs, M = Pd, Pt, Ir, Ru) that alter CO₂RR performance of Cu. In particular, surface alloying of Cu NCs with Ir switched product selectivity from C₂H₄ to HCOOH. Cu/Cu_1−xIr_x NCs exhibited superior HCOOH activity and stability compared with a Sn catalyst, which is a well-known element for producing HCOOH. Furthermore, Ir surface alloying preserved the cubic morphology of Cu NCs, whereas pure Cu degraded into nanograins. Our findings highlight a valuable approach to controlling reaction pathways through heteroatom interfaces and to designing highly active and stable electrocatalysts.