Single-Atom Catalysts Dispersed on Graphitic Carbon Nitride (g-CN): Eley-Rideal-Driven CO-to-Ethanol Conversion.

The electrochemical reduction of carbon monoxide (COER) offers a promising route for generating value-added multi-carbon (C) products, such as ethanol, but achieving high catalytic performance remains a significant challenge. Herein, we performed comprehensive density functional theory (DFT) computations to evaluate CO-to-ethanol conversion on single metal atoms anchored on graphitic carbon nitride (TM/g-CN). We showed that these metal atoms stably coordinate with edge N sites of g-CN to form active catalytic centers. Screening 20 TM/g-CN candidates, we identified V/g-CN and Zn/g-CN as optimal catalysts: both exhibit low free-energy barriers (<0.50 eV) for the key CO hydrogenation steps and facilitate C-C coupling via an Eley-Rideal mechanism with a negligible kinetic barrier (~0.10 eV) to yield ethanol at low limiting potentials, which explains their superior COER performance. An analysis of d-band centers, charge transfer, and bonding-antibonding orbital distributions revealed the origin of their activity. This work provides theoretical insights and useful guidelines for designing high-performance single-atom COER catalysts.