Atomically Dispersed Cerium Sites Immobilized on Vanadium Vacancies of Monolayer Nickel-Vanadium Layered Double Hydroxide: Accelerating Water Splitting Kinetics

Rational design of efficient single-atom catalysts is a potential avenue to mitigate the sluggish oxygen evolution reaction (OER) kinetics. Adopting appropriate matrixes to stabilize the single-atom active centers with the optimized geometric and electronic structure plays an essential role in enhancing catalytic activities. Herein, massive isolated Ce atoms are successfully anchored on monolayer nickel-vanadium layered double hydroxide support (Ce SAs/m-NiV LDH) via the vanadium defects trapping strategy, resulting in stabilized Ce single-atom with the maximum loading of 8.07 wt.%. Benefitting from the strong synergetic electronic interaction between Ce single atoms and monolayer NiV LDH matrix, thus-prepared catalyst possesses favorable OER (209 mV @ 10 mA cm-2) and water electrolysis performance (1.47 V @ 10 mA cm-2), surpassing other catalysts and even the commercial RuO2 catalyst. Density functional theory (DFT) calculations in combination with in situ electrochemical impedance spectroscopy analysis reveal that the immobilization of monatomic Ce can effectively narrow the band gap and strengthen the density states near the Fermi level as well as more easily adsorb the surficial OH-, leading to a lower charge transfer barrier and faster water splitting kinetics. The novel V vacancies trapped Ce single-atom catalyst is successfully constructed on the monolayer nickel-vanadium layered double hydroxide (NiV LDH). The physicochemical characterization and theoretical calculations demonstrate that the incorporation of single Ce atoms delivers a positive effect. Specifically, the synergistic effect results from the strong electronic coupling interactions between the Ce single-atom and monolayer NiV LDH matrix inducing an enhanced water electrolysis kinetics.image

Automated summary

Designing efficient single-atom catalysts is an effective strategy to enhance the kinetics of the oxygen evolution reaction. In this study, massive isolated Ce atoms are successfully anchored on a monolayer nickel-vanadium layered double hydroxide support, resulting in a stable Ce single-atom catalyst with enhanced catalytic activities. The strong electronic coupling interactions between the Ce single atoms and the monolayer NiV LDH matrix contribute to the improved water electrolysis kinetics.