Unexpected visible light driven photocatalytic activity without cocatalysts and sacrificial reagents from a (GaN)1-x(ZnO)x solid solution synthesized at high pressure over the entire composition rangeElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ra08509e

• Main Authors: Dharmagunawardhane, H. A. Naveen, James, Alwin, Wu, Qiyuan, Woerner, William R, Palomino, Robert M, Sinclair, Alexandra, Orlov, Alexander, Parise, John B
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c7ra08509e

Optical and photocatalytic properties were determined for the solid solution series (GaN) 1- x (ZnO) x synthesized at high pressure over the entire compositional range ( x = 0.07 to 0.9). We report for the first time photocatalytic H 2 evolution activity from water for (GaN) 1- x (ZnO) x without cocatalysts, pH modifiers and sacrificial reagents. Syntheses were carried out by reacting GaN and ZnO in appropriate amounts at temperatures ranging from 1150 to 1200 °C, and at a pressure of 1 GPa. ZnGa 2 O 4 was observed as a second phase, with the amount decreasing from 12.8 wt% at x = 0.07 to ∼0.5 wt% at x = 0.9. The smallest band gap of 2.65 eV and the largest average photocatalytic H 2 evolution rate of 2.31 μmol h −1 were observed at x = 0.51. Samples with x = 0.07, 0.24 and 0.76 have band gaps of 2.89 eV, 2.78 eV and 2.83 eV, and average hydrogen evolution rates of 1.8 μmol h −1 , 0.55 μmol h −1 and 0.48 μmol h −1 , respectively. The sample with x = 0.9 has a band gap of 2.82 eV, but did not evolve hydrogen. An extended photocatalytic test showed considerable reduction of activity over 20 hours. (GaN) 1- x (ZnO) x synthesized at high pressure produces H 2 in the presence of visible light without any cocatalysts or sacrificial reagents.