Modulation of surface oxygen vacancies on bismuth-rich Bi5O7I nanoparticles for efficiently boosting photocatalytic overall water splitting

To promote the spatial separation of photogenerated charge carriers is a critical challenge in the practical application of photocatalytic reaction. Surface oxygen vacancies (OVs) of catalysts have been confirmed to play a significant role for boosting photocatalytic quantum efficiency. Herein, Bi5O7I nanoparticles with abundant oxygen vacancies (DBOI) were prepared via a facile solution method. STEM-HAADF, HRTEM, low temperature EPR, XPS and PAS measurements were adopted to demonstrate the surface OVs. DFT calculations confirmed a DOS appeared in the forbidden band and the band gap of DBOI was consequently reduced. The surface OVs make DBOI have more coordinately unsaturated sites and defect states, functioning as the traps to capture charge carriers and reactants and thus effectively accelerate photocatalytic reaction. The optimal production rate of H2, O2 and H2O2 without cocatalyst over DBOI was respectively 1.18, 106.7 and 3.05 mmol h−1 g−1, which manifested significant improvement than Bi5O7I with less OVs. This work presented that surface OVs can endow Bi5O7I nanoparticles with efficient charge separation to acquire superior photocatalytic overall water splitting activity.