Constructing CoP/NiP Heterostructure Confined Ru Sub-Nanoclusters for Enhanced Water Splitting in Wide pH Conditions.

Developing efficient electrocatalysts for water splitting is of great significance for realizing sustainable energy conversion. In this work, Ru sub-nanoclusters anchored on cobalt-nickel bimetallic phosphides (Ru-CoP/NiP) are constructed by an interfacial confinement strategy. Remarkably, Ru-CoP/NiP with low noble metal loading (33.1 µg cm) shows superior activity for hydrogen evolution reaction (HER) in all pH values, whose turnover frequency (TOF) is 8.7, 15.3, and 124.7 times higher than that of Pt/C in acidic, alkaline, and neutral conditions, respectively. Meanwhile, it only requires the overpotential of 171 mV@10 mA cm for oxygen evolution reaction (OER) and corresponding TOF is 20.3 times higher than that of RuO. More importantly, the Ru-CoP/NiP||Ru-CoP/NiP displays superior mass activity of 4017 mA mg at 2.0 V in flowing alkaline water electrolyzer, which is 105.1 times higher than that of Pt/C||IrO. In situ Raman spectroscopy demonstrates that the Ru sites in Ru-CoP/NiP play a key role for water splitting and follow the adsorption evolution mechanism toward OER. Further mechanism studies disclose the confined Ru atom contributes to the desorption of H during HER and the formation of O-O bond during OER, leading to fast reaction kinetics. This study emphasizes the importance of interface confinement for enhancing electrocatalytic activity.