Built‐In Electronic Asymmetry in PdCu/Cu Heterostructures Drives Bias‐Free Electrocatalytic Co‐Valorization of Nitroaromatics and Aldehydes

ABSTRACT

Paired electrocatalysis offers a compelling route to atom‐economical and energy‐efficient chemical synthesis by coupling complementary redox half‐reactions within a single process. Yet its practical implementation demands macroscopic reactor infrastructure whose inherent resistance and kinetic penalties erode the very efficiency gains the concept promises. Here, we report an interface‐engineered PdCu/Cu heterostructure (PdCu/OD‐Cu) in which the intrinsic work function difference between PdCu and Cu domains drives interfacial charge redistribution, establishing a built‐in electronic asymmetry that simultaneously optimizes nitroaromatic reduction on PdCu domains and aldehyde oxidation on Cu domains. This asymmetry enforces directional internal electron flow that synchronizes both half‐reactions without external circuits, ion‐exchange membranes, or applied bias, reducing the effective anode–cathode separation from the centimeter scale of conventional electrolyzers to the nanometer scale of individual catalyst particles. Isotope‐labeled differential electrochemical mass spectrometry establishes internal electrochemical electron transfer as the coupling mechanism, excluding transfer hydrogenation. The wireless platform achieves near‐quantitative nitroaromatic conversion with aniline selectivity exceeding 95% and aldehyde oxidation yields exceeding 97%, outperforming conventional membrane‐based H‐cells operated under identical conditions, even when the latter are supplied with an external bias. These results establish work function mismatch‐driven interfacial electronic asymmetry as a general design principle for paired electrocatalysis without an externally applied bias.