Tuning Microscopic Water Orientation in Nickel Single-Atom Catalyst for Commercial-Scale CO₂ Electrolysis to CO

Electrochemical CO₂ reduction (ECR) to carbon monoxide (CO) offers a sustainable route for fuel and chemical production. Achieving commercial-scale performance remains difficult, largely due to limited proton supply at high current densities. While single-atom catalysts exhibit excellent CO₂-to-CO selectivity, their isolated active sites limit simultaneous optimization of CO₂ activation and water dissociation. Recent studies have highlighted the impact of interfacial water orientation on water dissociation kinetics, but this factor remains underexplored in ECR systems. Here, we demonstrate that modifying Ni-N₄ catalysts with CeO₂ clusters alters the microscopic orientation of interfacial water, thereby enabling industrial-scale CO production. The CeO₂-modified Ni-N₄ achieves nearly 100% CO Faradaic efficiency at current densities ranging from 50 to 600 mA cm^‒2 in flow cell and maintains 96% at 800 mA cm^‒2. In a membrane electrode assembly, it sustains over 96% Faradaic efficiency across 50-400 mA cm^‒2 and maintains >95% for 118 h at 150 mA cm^‒2. Experimental and computational analyses reveal that CeO₂ shifts the water orientation from oxygen-down to hydrogen-down configurations, thereby lowering the energy barriers for water dissociation and accelerating protonation. This work demonstrates that interfacial water orientation manipulation is a powerful strategy to enhance the performance of single-atom catalysts in CO₂ electrolysis.