Porous Trimetallic PtRhCu Cubic Nanoboxes for Ethanol Electrooxidation

Direct ethanol fuel cells (DEFCs) have great activity as a green energy conversion device. However, the weak activity of most anode electrocatalysts for the C-C bond cleavage is an obstacle to the DEFCs development. Herein, a simple galvanic replacement reaction strategy to synthesize hollow and porous PtRhCu trimetallic nanoboxes (CNBs) with a tunable Pt/Rh atomic ratio is developed. For the ethanol oxidation reaction (EOR), PtRhCu CNBs show morphology and composition-dependent electrocatalytic activity. The composition optimized Pt54Rh4Cu42 CNBs exhibit excellent specific and mass activity and stability for the EOR, which is attributed to its unique geometric structure and synergistic effects. The hollow porous structure can effectively enhance the atomic utilization and mass transfer. The introduction of Cu improves the antipoisoning capability for CO. The introduction of Rh elevates the self-stability of PtRhCu CNBs. More importantly, further electrochemical results confirm that the introduction of Rh significantly promotes the cleavage of C-C bonds, leading to the transformation of the main catalytic pathway for EOR from C-2 to C-1 pathway. The real concentration detection for C-2 products (CH3COOH and CH3CHO) shows Pt54Rh4Cu42 CNBs have a nearly 11.5-fold C-1 pathway enhancement compared to Pt nanoparticles, showing an obvious selectivity enhancement for the C-1 pathway.