Trace‐Rh‐Enabled Holey PtCuRh Metallenes for Highly Efficient Ethanol Electrooxidation

Improving the energy efficiency of direct ethanol fuel cells (DEFCs) hinges on promoting deep ethanol electrooxidation toward CO 2 (C1 pathway) while sustaining high current output under practical operating potentials. Herein, we present a trace‐Rh‐enabled holey PtCuRh metallene (PtCuRh ML) built from five‐atomic‐layer (≈1.3 nm) nanosheets that couple an ultrathin porous architecture with trimetallic electronic synergy. Relative to PtCu metallene (PtCu ML) and commercial Pt nanoparticle (Pt cNP), PtCuRh ML exhibits a substantially lowered onset potential (0.26 V at 100 mA mg −1 ) and delivers 3103.8 mA mg Pt+Rh −1 at 0.8 V with a specific activity of 13.61 mA cm −2 , indicating accelerated intrinsic kinetics beyond surface‐area effects. Density functional theory (DFT) calculations reveal that electronic interactions among Pt, Cu, and Rh modulate the surface electronic structure and adsorption energetics, thereby facilitating CH 3 CO* dehydrogenation and accelerating C–C bond cleavage. Importantly, DEFC equipped with PtCuRh ML as the anodic catalyst reaches a peak power density of 27.5 mW cm −2 , more than threefold higher than that of Pt/C, highlighting the promise of holey metallenes for efficient ethanol‐to‐electricity conversion. These results establish the power of electronic and structural synergy in multimetallic metallenes, offering guiding principles for the design of advanced anodic catalysts for DEFCs.