Defective RuO2/TiO2 nano-heterostructure advances hydrogen production by electrochemical water splitting

Exploring highly active and stable catalysts toward hydrogen evolution reactions and oxygen evolution reactions (HER/OER) is the key for electrochemical water splitting. Herein, density functional theory (DFT) calculation results forecast that the defect-rich RuO2 and TiO2 nano-heterostructures can effectively adjust the electron structure of RuO2, and accelerate the water electrocatalysis, consequently reinforcing the intrinsic activity of the catalyst. Experimentally, to form an integrated nano-heterostructure, a facile approach is designed for in situ fabrication of TiO2 on Ti mesh (TM), simultaneously combined with defective RuO2 (D-RuO2) nanoparticles. Benefiting from the rich active sites, the D-RuO2/TiO2/TM nano-heterostructure formed provides current densities of 50 mA/cm2 at 71 mV for HER and 10 mA/cm2 at 296 mV for OER in alkaline media. For overall water splitting, the electrolyzer assembled with D-RuO2/TiO2/TM electrode can reach 10 mA/cm2 with a voltage of only 1.59 V. Moreover, under a fixed current density, such an electrolyzer also achieves an outstanding stability.