Realization of high photocatalytic hydrogen generation activity by nanostructured Ga1-xZnxO1-zNz solid-solution without co-catalyst

摘要

Photocatalysis requires light absorption as well as efficient extraction of the photo-generated electron hole pairs to chemically active sites. To avoid electron hole recombination, we need tailored nanostructures which can demonstrate novel light absorption and thermodynamic properties. This work shows that band gap modificationarrowing due to the formation of solid solution along with an increased surface area of the nanostructures are ideal for solar harvesting and is a self sufficient photocatalytic agent even in absence of a co-catalyst. The present study suggests that the rate of H-2 production for GaN was negligible and it increased to 32.43 mu mol/g/h for the solid solution under visible light irradiation (>400 nm) even in the absence of a co-catalyst. The apparent quantum yield (AQY) efficiency of H-2 evolution was found to be 0.8%. This highly desirable increased H-2 generation activity is attributed to the additional linewidth broadening in the photoluminescence spectra of nanostructured wurtzite Ga1-xZnxO1-zNz solid-solution due to Ga/Zn and N/O interdiffusion giving rise to a modified bandgap and N2p-O2p interaction in the lattice. These inferences are also corroborated by diffuse reflectance spectra of the samples. For the first time, origin of hitherto unreported weak features appearing in the low energy Raman spectrum is also discussed. A series of characterization tools including structural, microstructural, optical, spectroscopic and Photocatalytic hydrogen production studies were employed to support our claim. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.