In Situ Electronic Redistribution Tuning of NiCo2S4 Nanosheets for Enhanced Electrocatalysis

Abstract Metal Ru and vacancy engineering play an important role in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, there are few reports targeted on electrocatalysts by simultaneously employing these two strategies. Herein, theoretical calculation firstly predicts that Ru and V S can regulate the adsorption energy of OER/HER intermediates for NiCo 2 S 4 electrocatalysts. Then, a facile solvothermal‐photochemical strategy is utilized to synthesis series NiCo 2 S 4 samples: through filling the solvothermal‐created V S in NiCo 2 S 4–x with Ru single atoms (Ru‐NiCo 2 S 4–x ) under ultraviolet irradiation as OER catalysts. Besides, Ru nanoclusters are introduced into NiCo 2 S 4 without V S (Ru‐NiCo 2 S 4 ) for HER. As a result, the OER exchange current density of NiCo 2 S 4–x is prominently boosted after decoration of Ru single atom, which possesses an eminently low overpotential of 190 mV@50 mA cm −2 , while Ru‐NiCo 2 S 4 shows superior HER performance (32 mV@10 mA cm −2 ) compared with Ru‐NiCo 2 S 4–x , surpassing most reported electrocatalytic materials. Moreover, Ru‐NiCo 2 S 4–x //Ru‐NiCo 2 S 4 exhibits remarkable stability and catalytic performance in the overall water splitting, with a cell voltage value of 1.46 V at 10 mA cm −2 in 1.0 m KOH. Bader charge analysis unravels the “restricted‐delocalized‐restricted” phenomenon between electrons promote the electron interactions, which in turn improves electrochemical performance.