Construction of Ti³⁺ self-doped TiO₂/BCN heterojunction with enhanced photoelectrochemical performance for water splitting

Ti³⁺ self-doped TiO₂/BCN heterojunction (Ti³⁺-TiO₂/BCN) was constructed via a hydrothermal method with using NaBH₄ as reducing agent. The BCN nanosheets function as a good support to block the agglomeration of Ti³⁺-TiO₂ nanoparticles, which decreased the recombination of photogenerated charge carriers. The Ti³⁺-TiO₂/BCN sample exhibited enhanced electronic conductivity and absorption in visible light region because of the introduction of Ti³⁺ and oxygen vacancies (Ov). The as-prepared Ti³⁺-TiO₂/BCN sample showed enhanced photoelectrochemical (PEC) performance as confirmed by analyses of LSV, EIS, Bode plots and M–S. Under the visible light irradiation, the optimally Ti³⁺ self-doped TiO₂/BCN heterojunction sample yield a photocurrent density of ∼ 0.69 mA/cm² at 1.23 V versus RHE, which is over three times as high as BCN and TiO₂/BCN at the same conditions.