Electronic Structure Tuning in Cu-Co Dual Single Atom Catalysts for Enhanced COOH* Spillover and Electrocalytic CO Reduction Activity.

The development of efficient electrocatalysts for CO reduction to CO is challenging due to competing hydrogen evolution and intermediate over-stabilization. In this study, a Cu-Co dual single-atom catalyst (CuCo-DSAC) anchored on carbon black was synthesized via scalable pyrolysis. The catalyst achieves 98.5% CO Faradaic efficiency at 500 mA cm, maintaining > 95% selectivity across a 400 mV window with < 6% decay over 48 h, which is superior to the corresponding single-atom control samples. In situ spectroscopy and DFT calculations reveal a synergistic mechanism: Co sites activate CO and stabilize *COOH intermediates, while adjacent Cu sites facilitate CO desorption by lowering the energy barrier through charge redistribution. This dynamic buffer system mitigates active-site blocking and suppresses HER by weakening H adsorption. The electronic interplay between Cu and Co optimizes intermediate energetics, enabling industrial-level performance. This work demonstrates the potential of tailored dual-site architectures for complex electrocatalytic processes, offering a promising approach to overcoming traditional limitations.