Engineering the oxygen vacancies enables Ni single-atom catalyst for stable and efficient C-H activation

Ni single-atom catalysts (SACs) can perform with the extremely high activity in the activation of the C-H bond, however, deactivation caused by carbon deposition became the main obstacle for commercialization. Herein, Ni/CeO₂ SAC was synthesized and employed in dry reforming of methane (DRM) reaction. The oxygen vacancies (O_V) with different concentrations were successfully regulated on CeO₂ surface by the replacement of Ce⁴⁺ cation by a smaller-size cation M (M= Mg, Co, Zn). The catalyst with the highest O_V concentration has performed with the highest activity retention and a high turnover frequency of methane (14.5 s⁻¹). During the DRM process, along with the increase of the O_V concentration from 21.9% to 30.8%, the amount of carbon deposition decreased by 50%. The effective C-H activation function from Ni SACs and CO₂ activation function from O_V were synergistically combined, leading to a high activity of methane conversion and an effective carbon removal process in the O_V-SAC catalytic system. This work provides a novel strategy to obtain a robust O_V-SAC catalytic system for efficient and stable C-H activation.