Lattice expansion in Ni3ZnC0.7@C weakening CO adsorption for efficient CO2 electroreduction

The metallic Ni catalyst suffers from strong binding with the *CO intermediate, resulting in poisoning of the catalyst surface. It is feasible to facilitate the generation of CO by alleviating the binding strength of the *CO intermediate on the Ni metal surface through a lattice expansion strategy. Here, Ni₃ZnC_0.7@C with lattice expansion was synthesized by co-doping with Zn and interstitial C through high-temperature pyrolysis. Structural characterization confirms that the lattice of Ni₃ZnC_0.7 expands by 5.47 % compared to Ni due to the co-doping of Zn and interstitial C. The Ni₃ZnC_0.7@C possesses excellent catalytic performance with Faradaic efficiency (FE) of CO exceeding 90 % over a wide potential range from −0.8 to −1.4 V versus reversible hydrogen electrode (vs. RHE) with a peak FE_CO of 96.6 % at −1.0 V vs. RHE. In membrane electrode assembly (MEA) testing, Ni₃ZnC_0.7@C achieves a FE_CO of 81.4 % at the industrial-level current density of 400 mA cm⁻². In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations reveal that the co-introduction of Zn and interstitial C in the Ni crystal can significantly promote the desorption of *CO intermediate, which facilitates the generation of CO. This study demonstrates a viable way for designing efficient transition metal catalysts for CO₂ electroreduction through lattice strain engineering.