Boosting the Ni–Zn interplay via O/N dual coordination for high-efficiency CO2 electroreduction

Abstract

Design of supportive atomic sites with a controllably adjusted coordinating environment is essential to advancing the reduction of CO2 to value-added fuels and chemicals and to achieving carbon neutralization. Herein, atomic Ni (Zn) sites that are uniquely coordinated with ternary Zn (Ni)/N/O ligands were successfully decorated on formamide-derived porous carbon nanomaterials, possibly forming an atomic structure of Ni(N2O1)-Zn(N2O1), as studied by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. With the mediation of additional O coordination, the Ni–Zn dual site induces significantly decreased desorption of molecular CO. The NiZn-NC decorated with rich Ni(N2O1)-Zn(N2O1) sites remarkably gained >97% CO Faraday efficiency over a wide potential range of ‒0.8 to ‒1.1 V (relative to reversible hydrogen electrode). Density functional theory computations suggest that the N/O dual coordination effectively modulates the electronic structure of the Ni–Zn duplex and optimizes the adsorption and conversion properties of CO2 and subsequent intermediates. Different from the conventional pathway of using Ni as the active site in the Ni–Zn duplex, it is found that the Ni-neighboring Zn sites in the Ni(N2O1)-Zn(N2O1) coordination showed much lower energy barriers of the CO2 protonation step and the subsequent dehydroxylation step.