Engineering single-atomic Ni sites stabilized with adjacent spinel nanoparticles to boost CO2 electroreduction

Abstract

Single-atom catalysts show great potential in the electrochemical CO₂ reduction reaction (CO₂RR), but face significant challenges in accelerating reaction kinetics. Herein, we develop a three-dimensional heterostructured MgAl₂O₄/Ni-N-C catalyst via a facile pyrolysis strategy, featuring abundant atomically dispersed Ni sites and ∼14 nm MgAl₂O₄ nanoparticles. The MgAl₂O₄ with rich oxygen vacancies is crucial for stabilizing Ni atoms and promoting CO₂ activation, thereby contributing to an excellent selectivity of nearly 100 % and good stability for CO production. The CO Faraday efficiency remains > 90 % within a large potential window (−0.57 to −0.97 V vs. RHE), and achieves the maximum of 98.7 % at −0.82 V. Theoretical calculations reveal that MgAl₂O₄ introduction can modulate the electron structure of Ni atoms, and accelerate the formation of *COOH intermediate, thus boosting CO₂RR performance. This research provides a novel approach for the design of high-efficiency single-atom catalysts for CO₂ conversion.