Ordered Copper Triangular Atomic Sites for Industrial-Grade Electromethanation of CO2 via Self-Regulated Adsorption of Reactants.

Copper single-atom catalysts have shown considerable potential for electrocatalytic CO₂ reduction reaction (CO₂RR) to methane but face constraints of low selectivity at industrial-grade current densities (>400 mA cm^-2) and limited economic viability. Herein, we report an ion exchange strategy to precisely construct ordered Cu triangular atomic sites loaded on poly(heptazine imide) (Cu TAS/PHI), achieving a methane Faradaic efficiency (FE) of 80.5% at 400 mA cm^-2 and >60% across 100-800 mA cm^-2. Remarkably, it enables CO₂ deuteration to high-value methane-d₄ with an FE of 75.1% at 700 mA cm^-2 and an estimated annual return on investment of 425.35%. In situ spectroscopy and theoretical calculations demonstrate that Cu triangular atomic sites enable strengthened adsorption and activation of CO₂, as well as balanced proton supply via self-regulated adsorption of reactants, thus favoring CO₂ deep hydrogenation over hydrogen evolution. Moreover, Cu TAS/PHI unlocks an energetically favorable *C(OH)₂ pathway, circumventing the conventional *CO pathway that typically yields diverse CO₂RR products. This work demonstrates a strategy to construct ordered multiatomic sites for highly selective CO₂RR at industrial-grade current density and highlights the extraordinary financial potential of electrocatalytic CO₂RR to produce high-value deuterated chemicals.