Interfacial Ru nanoclusters in tandem with single atoms on oxygen-vacancy regulated CeO2 for anion exchange membrane seawater-splitting

Abstract

A hydrogen spillover-bridged water dissociation/hydrogen formation could concurrently promote Volmer/Tafel process and improve the efficiency of hydrogen evolution reaction (HER) under alkaline conditions. However, it is still challenging to promote occurrence of hydrogen spillover for the large interfacial transport barriers of H₂O and hydrogen on active sites. Herein, the strategy of energy barrier gradient to induce hydrogen spillover was proposed by constructing Ru nanoclusters coupled with single atom onto oxygen vacancy cerium dioxide (Ru/CeO₂-Ov-2). Density functional theory (DFT) calculations uncover that the adsorption/desorption of H₂O occurs at the Ru clusters sites and then the dissociated H* spontaneously overflows from Ru clusters with high binding energy into the adjacent Ru single atom sites with low binding energy, which facilitate the hydrogen formation. Consequently, the synthesized Ru/CeO₂-Ov-2 exhibits a small overpotential of 41 mV at 10 mA cm⁻² and good stability at 500 mA cm⁻² for 100 h in alkaline seawater, which could be ascribed to the rapid hydrogen spillover and strong coupling interaction between Ru and CeO₂-O_V. This work provides a novel insight that synthesizing cooperative sites with energy barrier gradient helps to promote hydrogen spillover and accelerate the Volmer/Tafel process of HER.