Floating black TiO2-HGMs (hollow glass microspheres) with tunable defects for boosted seawater splitting and petroleum pollutants degradation

Developing photocatalytic materials with both recyclability and high activity has been a challenging task that has garnered increasing attention. In order to address this challenge, the black TiO₂ coated on the surface of hollow glass microsphere (HGMs) was prepared by using a facile sol-gel method and NaBH₄ solid-state reduction. Ti³⁺ and oxygen vacancies with tunable defects can be introduced by adjusting the amount of NaBH₄, which can not only enhance the absorption of visible light, but also improve the separation efficiency of photo-generated carriers. The as-prepared black TiO₂/HGMs manifested excellent recyclability and high photocatalytic activity in splitting seawater for H₂ evolution and degradation of diesel pollutants. Its hydrogen evolution rate and degradation efficiency are increased by 2.5 times and 1.3 times respectively compared to white TiO₂/HGMs and possess excellent cycling stability. Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy(XPS) and band gap analysis reveal the reason for the excellent photocatalytic performance of black TiO₂/HGMs. This study offers a unique approach for designing and preparing high-performance photocatalysts that can be easily recycled, which has potential applications in the environmental restoration and energy conversion fields.