Surface defects induced charge imbalance for boosting charge separation and solar-driven photocatalytic hydrogen evolution

Mesoporous TiO2 nanospheres with engineered surface defects are fabricated through surfactant-mediated self-assembly solvothermal approach combined with surface hydrogenation, which exhibit excellent solar-driven photocatalytic hydrogen evolution, due to surface defects induced charge imbalance improving charge separation, and unique spherical mesoporous structure supplying adequate surface-active sites and facilitating mass transfer. [Display omitted] •Surface defects induced charge imbalance promote charge separation.•Mesoporous TiO2 nanospheres with engineered surface defects are fabricated.•Nanoscale mesoporous spheres have closed packing and low surface energy.•It exhibits excellent solar-driven photocatalytic H2 evolution and high stability.•Surface defects and mesostructure favor charge separation and mass transfer. Low charge separation efficiency of semiconductor materials is the main obstacle for high-performance photocatalyst. Herein, we report surface defects engineered uniform mesoporous TiO2 nanospheres (DMTNSs) through surfactant-mediated self-assembly solvothermal approach combined with hydrogenation strategy to promote charge separation. The surface defects induced charge imbalance result in the formation of built-in field, which can promote photogenerated charge separation efficiently and be confirmed by experimental and density functional theory (DFT) calculations. Under AM 1.5G irradiation, the photocatalytic hydrogen evolution of DMTNSs is ~3.34 mmol h−1 g−1, almost 3.5 times higher than that of pristine non-defective TiO2 nanospheres (0.97 mmol h−1 g−1), due to the engineered surface defects narrowing the bandgap (~3.01 eV) and inducing charge imbalance to boost spatial charge separation and extend visible-light response. The defect induced charge imbalance strategy opens a new valuable perspective for fabricating other high-efficient oxide photocatalysts.