Compositional control of the photocatalytic activity of Ga2O3 nanocrystals enabled by defect-induced carrier trapping

Highlights: • We investigated photocatalytic activity of In³⁺ and Zn²⁺-doped Ga₂O₃ nanocrystals. • Doping allows for a control of charge carrier trapping in native defect states. • Carrier trapping in donor/acceptor defects studied by fast time-resolved emission. • Photocatalytic activity correlates with the donor-acceptor recombination lifetime. • We demonstrate a design of single-phase photocatalysts via compositional modulation. We investigated photocatalytic activity of γ-Ga₂O₃ nanocrystals with varying compositions. Substitutional doping with In³⁺ and Zn²⁺ allows for a control of charge carrier trapping in native defect states, which was studied by time-resolved photoluminescence spectroscopy. Doping nanocrystals with In³⁺ decreases while doping with Zn²⁺ increases the lifetime of the carriers trapped on donor and acceptor sites. The apparent rate constant for the photocatalytic dye degradation correlates well with the average donor-acceptor recombination lifetime, suggesting critical importance of carrier trapping for charge separation. The results of this work demonstrate the design of single-phase photocatalysts by controlling carrier trapping via compositional manipulation.