In-liquid Femtosecond Laser-Engineered Dual-Type Cation and Anion Vacancies Boost Photocatalysis

Surface vacancy engineering is crucial for enhancing charge separation in catalytic reactions. Traditional approaches have largely focused on single-type vacancies that trap either electrons or holes, limiting the effectiveness of overall redox reactions. Constructing dual-type metal-oxygen vacancies (VM-VO) facilitates trapping electrons and holes simultaneously and selectively. However, it poses significant challenges under equilibrium conditions due to the incompatible vacancy-formed conditions. Here, we utilize the non-equilibrium effect of the femtosecond-laser-processing technique to construct surface VM-VO. Taking TiO2 as a model, we confirm the surface engineering of dual-type titanium and oxygen vacancies (VTi-VO), synergistically boosting charge lifetime from 281.4 ps to 1507.6 ps, by 5.4 times. Remarkably, a dramatic enhancement of the apparent quantum efficiency in photocatalytic hydrogen evolution from 12.4% to 80.7% under 365 nm illumination is achieved. This work demonstrates a non-equilibrium femtosecond laser processing strategy for accurately carving VM-VO on metal oxides and highlights the significantly enhanced photocatalysis empowered by VM-VO-induced charge separation.