Double-defect-induced polarization enhanced OV-BiOBr/Cu2−xS high-low junction for boosted photoelectrochemical hydrogen evolution

In order to improve the carrier transfer driving force and separation efficiency, OV-BiOBr/Cu2−xS high-low junction with double defects (Oxygen vacancy and Copper vacancy) was successfully prepared by a facile two-step solvothermal in situ growth technique. OV-BiOBr/Cu2−xS-0.2 showed the highest hydrogen evolution rate (509.75 μmol·cm−2·h−1), which was 12.45, 6.94 and 3.44 times that of pure BiOBr, OV-BiOBr and BiOBr/Cu2−xS composite, respectively. Obvious free radicals (·OH and ·O2-) were observed in the dark state for the first time. Theoretical and experimental results demonstrate that the charge imbalance within OV-BiOBr/Cu2−xS intensifies after the introduction of the double defects, resulting in enhanced interfacial polarization phenomena. Boosted photoelectrochemical hydrogen evolution activities were achieved with the synergistic effect of the internal electric field and polarization electric field. This study will lay a scientific and experimental foundation for the preparation of high-performance photoelectrochemical anode materials with double defect heterojunction.