Highly photocatalytic p-type Cu2O thin films fabricated on a quartz glass substrate at 180°C in air, by spraying aqueous precursor solutions involving Cu(II) complexes

Abstract

ABSTRACT The p-type Cu2O thin films on a quartz glass substrate were facilely fabricated at 180°C in air by spraying aqueous precursor solutions. The spray solutions were prepared in a diluted ammonia solution by dissolving Cu(II) formate and ammonium formate whose molar ratios to Cu(II) ion were 0, 2, 6 and 14. In the cases of the molar ratios at 6 and 14, the Cu2O thin films of 140 and 350 nm thickness respectively indicated a highly photocatalytic activity under visible-light irradiation of 0.45 mW cm–2, and the pseudo-first-order rate constants of 0.056 and 0.087 min–1 were respectively obtained by tracing the discoloration of a methyl orange solution. The O-defect site was found in the Raman spectra of these photocatalytic thin films whose adhesion strength onto the quartz substrate were larger than 5.6 N. The morphology, chemical component, and optical and electrical properties were also examined in detail.