Enhanced Synergistic Catalysis of Novel Ag2O/CuO Nanosheets under Visible Light Illumination for the Photodecomposition of Three Dyes

Abstract Visible-light photocatalysis is considered a good alternative for effluent degradation, resulting in eco-friendly biodegradable products. Semiconductors derived bimetallic nanocomposites have sufficient bandgap potential for efficient effluent treatment upon their exposure to the visible light. In this work, Ag2O was deposited over CuO to improve the light captivating properties of the as-synthesized bimetallic catalyst. The bimetallic catalyst was studied for the photodegradation of three different azo dyes, by introducing persulfate as a sacrificial donor, under visible as well as sunlight irradiation. Novel leaf-like Ag2O/CuO catalyst has efficiently degraded 100% Congo Red (CR), 99.9% Rhodamine-B (RhB), and 97% Methyl Orange (MO) dyes within 6 mins, 15 mins, and 20 mins, respectively. Photodecomposition of all three dyes was studied at various pH solutions and the most efficient photodegradation was observed with a neutral pH solution. ESR and radical probe experiments were conducted to identify the active radical species and to reveal the reaction mechanism. SO4•− and HO• radicals were the influential radicals during the photodegradation reaction. Notably, Ag2O/CuO catalyst exhibited 100% photodegradation of Congo Red dye without the addition of persulfate within 8 mins, a superior characteristic than the other known bimetallic catalysts. The developed catalyst is easily recyclable and offered just a 1-2% decrease in its photocatalytic performance, for all three dyes, even after 5 consecutive cycles. Thus, the reported catalyst can be a suitable alternative to expensive rare-earth derived bimetallic catalysts and has a potential application for the detoxification of various organic pollutants, at the field scale.