Overall Water Splitting on (Ga_1-xZn_x)(N_1-xO_x) Solid Solution Photocatalyst:  Relationship between Physical Properties and Photocatalytic Activity

Abstract

The physical and photocatalytic properties of a novel solid solution between GaN and ZnO, (Ga(1-x)Zn(x))(N(1-x)O(x)), are investigated. Nitridation of a mixture of Ga(2)O(3) and ZnO at 1123 K for 5-30 h under NH(3) flow results in the formation of a (Ga(1-x)Zn(x))(N(1-x)O(x)) solid solution with x = 0.05-0.22. With increasing nitridation time, the zinc and oxygen concentrations decrease due to reduction of ZnO and volatilization of zinc, and the crystallinity and band gap energy of the product increase. The highest activity for overall water splitting is obtained for (Ga(1-x)Zn(x))(N(1-x)O(x)) with x = 0.12 after nitridation for 15 h. The crystallinity of the catalyst is also found to increase with increasing the ratio of ZnO to Ga(2)O(3) in the starting material, resulting in an increase in activity.

Hydrogen Production by Photoreforming of Renewable Substrates

“…Doping has been proposed with anions, which more likely shift the valence band to higher energy (reducing in any case the bandgap energy) [53,92]. Some examples of anions doping led however to very limited red-shift [14,18].…”

Hybrid density functional study of band alignment in ZnO–GaN and ZnO–(Ga1−xZnx)(N1−xOx)–GaN heterostructures

“…This trend is in good agreement with the experimental findings. 27 The tunable band gaps of (Ga 1-x Zn x )(N 1-x O x ) are suitable for overall water splitting under visible-light irradiation. .…”

Structural evolution in Pt/Ga-Zn-oxynitride catalysts for photocatalytic reforming of methanol

“…Ga-oxynitrides have a chemical formula of (Ga 1-x x )(N,O) and can adopt the wurtzite-type structure of the hexagonal GaN (GaN h ), in which O substitutes for N and the octahedral sites are randomly occupied by Ga and vacancies [3]. In Ref [8][9][10] a range of (Ga 1-x Zn x )(N 1-x O x ) materials were synthesized; these wurtzite-type phases can be regarded as solid solutions of the two constituents GaN and ZnO, in which Ga and Zn randomly occupy the octahedral cation sites.…”