LAUSR

For the electrochemical CO-2 reduction reaction (CO2RR), the single-metal atom catalysts (SACs) on N-doped carbon are considered promising alternatives to conventional catalysts owing to their unique electrocatalytic properties. However, environmentally friendly methods to prepare SACs are still required. Herein, Ni SAC was synthesized using lignin derived from biomass whose structural and chemical properties render it suitable as both a base carbon matrix and a metal chelating agent. The coordination environment of active Ni-Nx sites was readily manipulated by controlling thermal activation. The Ni SAC on lignin-derived N-doped carbon achieved an outstanding CO Faradaic efficiency of 98.2% at -0.9 V vs. RHE, which is comparable to those of conventional SACs. Experimental results combined with DFT calculations demonstrate the optimal conditions for manufacturing Ni SAC which is highly selective for CO-2-to-CO conversion and the effect of the electronic structure of Ni atom on CO2RR kinetics.