Ga doped ZnO photonic crystals with enhanced photocatalytic activity and its reaction mechanism

In this study, Ga doped ZnO photonic crystals were developed for the purpose of achieving the cooperative enhancement from the photonic crystals structure and Ga doping. The Ga doped ZnO photonic crystals with highly ordered skeleton structure could be obtained via a dip-coating infiltration method. By varying the pore diameter of photonic crystals, the slow photon effect could be found over the sample with a pore diameter of 217 nm and the corresponding electronic band gap absorption was enhanced. Moreover, the introduction of Ga increased the specific surface area of Ga doped ZnO photonic crystals while the concentration of hydroxyl oxygen on the surface decreased simultaneously, which formed a competitive relationship in determining the photocatalytic performance of Ga doped ZnO photonic crystals. The photocatalytic activities for the degradation of rhodamine B showed that 3 at% Ga doped ZnO photonic crystals with a pore diameter of 217 nm exhibited higher activity compared with other samples. The higher activity could be attributed to the slow photon effect from the photonic crystal structure and increased specific surface area after Ga doping. Furthermore, based on the results of the detection of radicals, the degradation mechanism was discussed in details.