Increased Photocatalytic Properties of Nanoporous GaN-Based MQWs/TiO2 with Nanoporous GaN Distributed Bragg Reflectors

Nanoporous gallium nitride (GaN)-based multiple quantum wells (MQWs) with nanoporous GaN distributed Bragg reflectors (NP-MQWs) are used as substrates for the regrowth of niobium (Nb) doped TiO2 thin films via pulsed laser deposition (PLD). Electrochemical tests present that nanoporous heterojunction structures of NP-MQWs-based TiO2 (NP-MQWs/TiO2) increase the separation and transfer efficiency of the photogenerated charge. Compared with as-grown MQWs-based TiO2 (AG-MQWs/TiO2), NP-MQWs/TiO2 shows significantly increased photodegradation amounts of Rhodamine B (RhB) at various pHs, which can be put down to decreased stress, improved crystal quality, and rising light absorption of the MQWs structure and the TiO2 layer. Moreover, the photocatalytic mechanism of NP-MQWs/TiO2 is revealed.