Band gap engineered Nb2O5 thin films fabricated from sol-gel processed modified precursors for enhanced photocatalytic activity: A comparative study

Abstract

Reactions of niobium (V) ethoxide (1) with 2,4-pentanedione derivatives [3-Chloro-2,4-pentanedione, 1,1,1-Trifluoro-2, 4 pentanedione, 3,3-Dimethyl-2,4-pentanedione,] afforded heteroleptic niobium alkoxide complexes [Nb(OEt)4 (CH3COCHClCOCH3)](2), [Nb(OEt)4(CF3COCH2COCH3)] (3) and [Nb(OEt)4(CH3COC(CH3)2COCH3)] (4). Two sets of Nb2O5 sculptured thin films (STFs) were deposited on ITO coated glass substrates by spin casting the gels obtained by sol gel processing of the synthesized complexes (2-4). One set of the films (Na, Nb and Nc) were calcined under ammonia gas flow and the other (a, b and c) under oxygen gas flow respectively at 500°C for 1h. A film (d) was also fabricated from niobium (V) ethoxide and calcined under oxygen gas flow at 500°C for 1h for comparisons with regard to structure, topography, optical and photocatalytic properties of Nb2O5. Crystal structure, topography, optical and photocatalytic properties of the films were determined by X-ray diffraction, atomic force microscopy, ellipsometry and UV-Vis spectroscopy. Significant band gap narrowing i.e. from 3.48 eV (d) to 2.73 eV (Nc) was observed for the films calcined under ammonia gas flux. Investigation of photodegradation of methylene blue (MB) by niobia films under UV irradiation demonstrated enhanced degradation efficiency of methylene blue dye. Copyright © 2018 VBRI Press.