Publications

Nanocrystalline Ga-Zn Oxynitride Materials: Minimized Defect Density for Improved Photocatalytic Activity?

Lukic, S. and Busser, G.W. and Zhang, S. and Menze, J. and Muhler, M. and Scheu, C. and Winterer, M.

ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE
Volume: 234 Pages: 1133-1153
DOI: 10.1515/zpch-2019-1432
Published: 2020

Abstract
We present an alternative synthesis strategy for developing nanocrystalline (Ga1-xZnx)(N1-xOx) semiconductors known to be very efficient photoabsorbers. In a first step we produce mixtures of highly crystalline β-Ga2O3 and wurtzite-type ZnO nanoparticles by chemical vapor synthesis. (Ga1-xZnx)(N1-xOx) nanoparticles of wurtzite structure are then formed by reaction of these precursor materials with ammonia. Microstructure as well as composition (zinc loss) changes with nitridation time: band gap energy, crystallite size and crystallinity increase, while defect density decreases with increasing nitridation time. Crystallite growth results in a corresponding decrease in specific surface area. In the UV regime photocatalytic activity for overall water splitting can be monitored for samples both before and after nitridation. We find a significantly lower photocatalytic activity in the nitrided samples, even though the crystallinity is significantly higher and the defect density is significantly lower after nitridation. Both properties should have led to a lower probability for charge carrier recombination, and, consequently, to a higher photocatalytic activity. © 2019 Walter de Gruyter GmbH, Berlin/Boston 2019.

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