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 center dot O-2(-) over bar and center dot OH radicals, respectively. The NRO process sheds light on the preparation of a nanoscale dual-phase photocatalyst containing nitride and oxide.