Modulating the Electronic Properties of Single Ni Atom Catalyst via First‐Shell Coordination Engineering to Boost Electrocatalytic Flue Gas CO₂ Reduction

Abstract Electrochemical converting CO₂ to CO via single atom catalyst is an effective strategy for reducing CO₂ concentration in the atmosphere and achieving a carbon‐neutral cycle. However, the relatively low CO₂ concentration in industrial processes and large energy barriers for activating CO₂ severely obstruct the actual application. Reasonably modulating the coordination shell of the active center is an effective strategy to enhance the activity of single atom catalysts. Herein, a well‐designed single‐atom electrocatalyst Ni‐N₃S₁ is developed via a large‐scale synthesis strategy. The constructed Ni‐N₃S‐C exhibits a superior catalytic activity than Ni‐N₄‐C for CO₂ to CO conversion in H‐type cells, and the industrial‐level current density with excellent durability at a wide pH range can be achieved in gas‐diffusion flow cells. Experimental results and density functional theory (DFT) calculation demonstrate that introducing low electronegative S in an active center can significantly regulate the electronic structure of the active site, promoting the CO₂ adsorption capacity and decreasing the energy barrier of *COOH formation, thus the larger size and flexibility of sulfur mitigate the nickel agglomeration and enhance the stability of Ni‐N₃S‐C catalyst. This work provides an effective strategy for designing highly active single‐atom catalysts for electrocatalysis via modulating the coordination shell of reactive sites.