Improved charge separation of NiS nanoparticles modified defect-engineered black TiO₂ hollow nanotubes for boosting solar-driven photocatalytic H₂ evolution

NiS nanoparticles modified black TiO₂ hollow nanotubes (NBTNs) are successfully synthesized via surface hydrogenation and the facile solvothermal method. The unique structure with intensified surface and interface characteristics endow NBTNs with more catalytic sites, and increase charge carrier separation efficiency with an extended charge lifetime, overwhelmingly promoting its photocatalytic performance. The resultant NBTNs possess a relatively high surface area and pore size of ∼89 m² g⁻¹ and ∼9.8 nm, respectively. The resultant NBTNs exhibit an excellent solar-driven photocatalytic hydrogen rate (3.17 mmol h⁻¹ g⁻¹), which is almost as high as that of Pt as cocatalyst, in which the apparent quantum yield of 5.4% (420 nm) is recorded for the NBTNs sample. Moreover, the turnover number can be up to 116 000 within 48 h and the turnover frequency is 2400 for NiS. This novel strategy could provide a better understanding of cocatalyst photocatalytic mechanisms, and a scheme simultaneously regulating the morphology and structure of photocatalysts for promoting H₂ generation. (paper)