Breaking the symmetry of dual-atom catalysts enables efficient electrocatalytic CO2 reduction over ultra-wide potential window

Achieving high-selectivity electrocatalytic CO 2 reduction (CO 2 RR) across a broad potential window is crucial for utilizing intermittent renewable electricity. Herein, we developed a precise synthesis strategy to break the symmetrical coordination environment of CuNi-NCNTs dual-atom catalysts (DACs) by introducing sulfur to construct asymmetrical DAC of CuNi-SNCNTs on carbon nanotubes. Investigations reveal that doping S, with lower electronegativity and empty 3d orbitals compared to N, establishes robust electronic modulator around bridged Cu–Ni dual sites, accelerating proton feeding to CO 2 , whereas suppressing HER. Particularly, the optimized coordination environment enables effective synergy between Cu and Ni, wherein Ni manages CO 2 activation while Cu assists water dissociation, facilitating the key intermediate formation. Consequently, the asymmetrical CuNi-SNCNTs DAC can achieve the constant ∼100% Faradaic efficiency for CO 2 -to-CO conversion over an ultra-wide potential window of 1500 mV from −0.3 to −1.8 V vs. RHE, and a high CO partial current density of 821 mA cm −2 . • The CuNi-SNCNTs DAC catalyst anchored on CNTs enhances active sites. • Doping S in CuNi-SNCNTs to break the symmetry of the catalyst can suppress HER. • The Cu–Ni dual atoms boost catalysis by synergistically activating CO 2 and H 2 O. • CuNi-SNCNTs exhibits ∼100% FE CO across 1.5 V window, achieving a high CO partial current density of 821 mA cm −2 .