Efficient light harvesting over a CdS/In2O3 photonic crystal photocatalyst for hydrogenation of 4-nitroaniline to p-phenylenediamine

Efficient light harvesting was observed over CdS photodeposited on In2O3 photonic crystals during the photocatalytic hydrogenation of 4-nitroaniline to p-phenylenediamine. The highest conversion of 4-nitroaniline and selectivity of p-phenylenediamine over the In2O3 photonic crystal supported CdS were similar to 93% and similar to 99%, respectively, which were better than that achieved for commercial hexagonal CdS. The existence of the photonic crystal structure was responsible for the higher efficiency of In2O3 photonic crystal supported CdS. The ordered structure facilitated the mass transport. The elaborate tuning of the photonic band gap activated the slow photon enhancement effect on the blue edge for intensifying the light harvesting efficiency of CdS. Moreover, CdS supported on In2O3 photonic crystals exhibited higher photocatalytic stability than that on the In2O3 nanocrystals. The mechanism of photocatalytic hydrogenation over In2O3 photonic crystal supported CdS was discussed. Our results provided guidance for efficiently utilizing light for photocatalysis by applying photonic crystals as support.