Co-introduction of oxygen vacancies and cocatalysts into protonic titanate derived TiO2 nanoparticles for enhanced photocatalytic hydrogen production

Abstract

Photocatalytically splitting water into hydrogen upon semiconductors has tremendous potential for alleviating environmental and energy crisis issues. There is increasing attention on improving solar light utilization and engineering photogenerated charge transfer of TiO₂ photocatalyst because it has advantages of low cost, non-toxicity, and high chemical stability. Herein, oxygen vacancies and cocatalysts (Cu and MoS₂) were simultaneously introduced into TiO₂ nanoparticles from protonic titanate by a one-pot solvothermal method. The composition and structure characterization confirmed that the pristine TiO₂ nanoparticle was rich in oxygen vacancies. The photocatalytic performances of the composites were evaluated by solar-to-hydrogen evolution test. The results revealed that both Cu-TiO₂ and MoS₂-TiO₂ could improve the photocatalytic hydrogen evolution ability. Among them, 0.8% Cu-TiO₂ showed the best hydrogen evolution rate of 7245.01 μmol·g⁻¹·h⁻¹, which was 3.57 and 1.34 times of 1.25% MoS₂-TiO₂ (2726.22 μmol·g⁻¹·h⁻¹) and pristine TiO₂ material (2028.46 μmol·g⁻¹·h⁻¹), respectively. These two kinds of composites also had good stability for hydrogen evolution. Combined with the results of photocurrent density and electrochemical impedance spectra, the incorporation of oxygen vacancies and cocatalysts (Cu and MoS₂) could not only enhance the light-harvesting of TiO₂ but also improve the separation and transfer capabilities of light-induced charge carriers, thus promoting water splitting to hydrogen.