Construction of dynamic p-n junctions at atomic-scale for unanticipated photocatalytic oxidation activity

Dynamic p-n junction can drive a drift of electrons from p-type to n-type side, and that of holes in the opposite direction simultaneously, which offers a promising avenue for next generation of advanced photocatalysts. However, construction of dynamic p-n junctions still remains challenging. Herein, dynamic p-n junctions at atomic-scale are constructed by hybridizing two n-type semiconductors, Zn-doped TiO2 and P-doped C3N4. The catalyst (Z0.01T/CNP-4) gives a stable and remarkable photo-oxidation ability for tetracycline hydrochloride (TCH), giving a much higher space-time yield than previously reported. h+, •O2−, and •OH radicals are main active species for the TCH photo-oxidation. Most importantly, •O2− species react with photo-generated electrons rapidly separated via atomic-level p-n junctions to yield H2O2 that further promotes the TCH photo-oxidation process. These findings provide new hints in fabricating more novel dynamic p-n junctions for effectively utilizing both photo-generated electrons and holes in the meanwhile to achieve the full potential of photocatalytic reactions.