Microenvironment Engineering of Ru Single-Atom Catalysts by Regulating the Cation Vacancies in NiFe-Layered Double Hydroxides

Single-atom catalysts (SACs) with rationally designed microenvironments (defined as coordination environments and electronic configurations) show superior catalytic activity, selectivity, and stability in a majority of reactions. However, the construction of isolated SACs with definite microenvironments to understand the microenvironment-activity relationship is still challenging. Herein, a facile strategy is developed to construct a series of Ru SACs with tunable geometric and electronic structures by employing NiFe-layered double hydroxides (LDH) with different cation vacancies (M-II or M-III) as supports. Detailed spectroscopic characterizations and theoretical calculations reveal that the Ru-O coordination environments and electronic configurations of single-atomic Ru can be easily tailored by the vacancy regulation. As a result, isolated Ru atoms anchored by M-III vacancies (denoted as Ru-1/LDH-V-III) with Ru-O-Ni coordination environments facilitate the desorption of benzaldehyde, thus leading to higher efficiency of benzyl alcohol oxidation with a superior turnover frequency of 1331 h(-1).