Grain-Boundary-Rich Pt/Co₃O₄ Nanosheets for Solar-Driven Overall Water Splitting

Interfacial engineering is considered an effective strategy to improve the electrochemical water-splitting activity of catalysts by modulating the local electronic structure to expose more active sites. Therefore, we report a platinum-cobaltic oxide nanosheets (Pt/Co₃O₄ NSs) with plentiful grain boundary as the efficient bifunctional electrocatalyst for water splitting. The Pt/Co₃O₄ NSs exhibit a low overpotential of 55 and 201 mV at a current density of 10 mA cm^-2 for the hydrogen evolution reaction and oxygen evolution reaction in 1.0 M potassium hydroxide, respectively. A negligible degradation of 1.52 V at a current density of 10 mA cm^-2 after continuous operation for 100 h, demonstrates the long-term stability of the catalyst. Furthermore, the overall water-splitting performance of the Pt/Co₃O₄ NSs surpasses that of the commercial Pt/C||RuO₂. The density functional theory calculation results explain that the improvement of catalyst activity is attributed to the moderate adsorption/desorption energy of *H and the low reaction energy barrier of the rate-determining step. This work presents a novel vision to design bifunctional catalysts for the storage and conversion of hydrogen energy.