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Structure Analysis and Photocatalytic Properties of Spinel Zinc Gallium Oxonitrides
Author(s) -
Ram Boppana Venkata Bharat,
Schmidt Heather,
Jiao Feng,
Doren Douglas J.,
Lobo Raul F.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101196
Subject(s) - photocatalysis , rhodamine b , spinel , zinc , band gap , photochemistry , inorganic chemistry , materials science , photodegradation , catalysis , raman spectroscopy , chemistry , organic chemistry , physics , optoelectronics , optics , metallurgy
Abstract This report describes a detailed structural, electronic, and catalytic characterization of zinc gallium oxonitride photocatalysts with a spinel crystal structure. The bandgap decreases to less than 3 eV with increasing nitrogen content (<3 wt %) and these photocatalysts are active in visible light (λ>420 nm) for the degradation of cresol and rhodamine B. Density functional theory calculations show that this bandgap reduction is in part associated with hybridization between the dopant N 2p states and Zn 3d orbitals at the top of the valence band. X‐ray photoelectron measurements indicate that nitrogen is indeed interacting with the oxide precursor through the formation of both nitride‐ and oxonitride‐type species. The incorporation of nitrogen reduces the uniformity of the local structure of the spinel Zn‐Ga‐O‐N (ZGON) species, as reflected in X‐ray absorption spectra and Raman measurements relative to zinc gallate, which suggests the presence of defects. The oxonitrides exhibit faster photocatalytic rates of reaction than the oxide precursor. The degradation mechanisms were determined to be via the attack by hydroxyl radicals and holes for rhodamine B and cresol, respectively. Addition of Pt as a co‐catalyst increased the rate of photodegradation, a result attributed to better charge separation.