Hierarchical Dual Single-Atom Catalysts with Coupled CoN₄ and NiN₄ Moieties for Industrial-Level CO₂ Electroreduction to Syngas

Renewable-driven electrochemical CO₂ reduction reaction (CO₂RR) to syngas is an encouraging alternative strategy to traditional fossil fuel-based syngas production, and the development of industrial-level electrocatalysts is vital. Herein, based on theoretical optimization of metal species, hierarchical Co_xNi_1–x–N–C dual single-atom catalyst (DSAC) with individual NiN₄ (CO preferential) and CoN₄ (H₂ preferential) moieties was constructed by a two-step pyrolysis route. The Co_0.5Ni_0.5–N–C exhibits a stable CO Faradaic efficiency of 50 ± 5% and an industrial-level current density of 101–365 mA cm^–2 in an ultrawide potential window of −0.5 to −1.1 V. The CO/H₂ ratio of syngas can be conveniently tuned by regulating the Co/Ni ratio. The coupled effect of NiN₄ and CoN₄ moieties under a local high-pH microenvironment is responsible for the regulation of the CO/H₂ selectivity and yield for the Co_xNi_1–x–N–C catalyst, which is not present in the mixed Co–N–C and Ni–N–C catalyst. This study provides a promising DSAC strategy for achieving industrial-level syngas production via CO₂RR.