A highly efficient dual-phase GaN(O)/Nb₂O₅(N) photocatalyst prepared through nitridation and reoxidation process for NO removal

Dual-phase Nb₂O₅(N)/GaN(O) photocatalyst with N doping in Nb₂O₅ and O doping in GaN was synthesized via nitridation and re-oxidation (NRO) of GaNbO₄. The NRO process induced the formation of nanosized heterojunctions between the Nb₂O₅(N) and GaN(O) phase. The utilization of GaNbO₄ as a precursor enhances the nitridation process than pure gallium oxide while retards the oxidation of pure niobium nitride to give an improved doping composite showing a desired bandgap around 2.0 eV with indirect transition. The photocatalyst exhibited very high NO removal efficiency (nearly 100%) under visible-light and very high selectivity (89%) for the formation of ionic species rather than more toxic NO₂, which could be related to the intimate junction between the GaN(O) phase with high conduction band minimum and Nb₂O₅ phase with low valence band maximum for the simultaneous generation of •O₂¯ and •OH radicals, respectively. The NRO process sheds light on the preparation of a nanoscale dual-phase photocatalyst containing nitride and oxide.