Quaternary PdAuAgPt alloy branched nanosheets for enhanced C1 pathway selectivity in ethanol oxidation

The ethanol oxidation reaction (EOR) is plagued by sluggish kinetics and inefficient C–C bond cleavage, which restricts complete 12-electron oxidation via the C1 pathway in direct ethanol fuel cells. Herein, quaternary PdAuAgPt alloy dendritic nanosheets (DNSs) are synthesized via galvanic replacement of pristine, densely branched PdAuAg DNS templates with H 2 PtCl 6 . By adjusting the Pt precursor dosage, the branch density and surface structure of the DNSs are finely modulated, generating abundant low-coordination active sites at the optimal composition. Electrochemical evaluation shows that the optimized catalyst delivers a mass activity of 1673.3 mA mg −1 and a specific activity of 13.660 mA cm −2 in alkaline media, substantially outperforming the PdAuAg DNS counterpart and commercial Pt/C, along with accelerated reaction kinetics and enhanced anti-poisoning tolerance. Notably, in situ surface-enhanced Raman spectroscopy confirms the activation of the C1 pathway, as evidenced by a distinct *CO 3 2 ⁻ band at ∼1066 cm −1 observed at 0.92 V versus RHE, directly demonstrating efficient C–C bond scission. Density functional theory calculations confirm that alloying-mediated electronic structure modulation lowers the kinetic barrier of C–C bond cleavage, which represents the intrinsic origin of the enhanced C1 pathway selectivity on the PdAuAgPt catalyst. This work provides a robust multimetallic nanostructure for high-performance EOR electrocatalysis and offers mechanistic insights into steering reaction selectivity toward the C1 pathway.