Ultrafine and superdispersed heterojunction of RuO2/TiO2 as an efficient pH-Universal bifunctional water-splitting electrocatalyst

Electrolysis of water to produce green hydrogen is one of the important ways to achieve efficient utilization of renewable energy. Herein, we use TiO2 nanoparticles as supports, utilizing their abundant oxygen-containing functional groups on the surface to adsorb ruthenium precursors. A bifunctional electrocatalyst with Mott-Schottky heterojunction structure can be obtained (RuO2/TiO2). Due to the Mott-Schottky effect, self-driven charge transfer occurs at the RuO2/TiO2 heterojunction interface, thereby optimizing the electronic structure of the material. Under both acidic and alkaline conditions, RuO2/TiO2-250 exhibits excellent HER and OER catalytic performance. In 0.5 M H2SO4, the overpotential of HER and OER was only 62 mV and 201 mV at 10 mA cm−2, respectively. In 1 M KOH, the overpotential of HER and OER was only 22 mV and 301 mV at 10 mA cm−2, respectively. Moreover, RuO2 nanoparticles achieve ultrafine and superdispersed effects, fully exposing active sites, thus RuO2/TiO2-250 has high mass activity. In 0.5 M H2SO4, the mass activity of HER (overpotential: 50 mV) and OER (overpotential: 300 mV) of RuO2/TiO2-250 reached 3.24 A mg−1 and 31.3 A mg−1, respectively. Under acidic conditions, when RuO2/TiO2-250 was used as both an anode and cathode catalyst for water-splitting, the decomposition voltage was only 1.454 V.