Band gap modified zinc oxide nanoparticles: an efficient visible light active catalyst for wastewater treatment
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ORIGINAL PAPER
Band gap modified zinc oxide nanoparticles: an efficient visible light active catalyst for wastewater treatment S. S. Sharma1,2 · S. Palaty1 · A. K. John1 Received: 18 April 2020 / Revised: 21 July 2020 / Accepted: 30 September 2020 © Islamic Azad University (IAU) 2020
Abstract The use of photocatalysis in wastewater treatment using low cost photocatalyst plays a vital role in thwarting the enigma of water pollution. In this work, we report synthesis of metal- and non-metal-doped zinc oxide (ZnO) nanostructures via solid state, solvent and surfactant-free microwave-assisted thermal decomposition method. HRTEM images confirm the formation of highly crystalline nanorod morphology in the case of sodium-doped ZnO. The photocatalytic activity of the synthesized samples initially assessed by the degradation of methylene blue under visible light illumination suggests that SZO-3 (15wt% Na-doped) with admirable degradation rate (95% in 180 min with apparent rate constant of 1.69 × 10–2 min−1) and tenacious photostability envisages its potential applications in water treatment processes. The coalescence of ultrasound, visible light and catalyst resulted in augmented degradation (99.5%) in 60 min. Keywords Sonophotocatalysis · Water treatment · Doped zinc oxide nanostructures · Band gap engineering
Introduction Over the last decade, researchers around the globe have been thriving to address the water pollution resulting from the accumulation of noxious organic dyes from numerous industries. The decomposition of organic dyes in effluent water by semiconductor-mediated catalysis by utilizing ultrasonic irradiation and photocatalysis is at the forefront among the diverse methods (Qi et al. 2017; Horzum et al. 2018; Liao et al. 2018; Nenavathu et al. 2018; Zhou and Fu 2018). Zinc oxide (ZnO) nanoparticles play a prominent role in photocatalysis as well as sonocatalysis, and its competence is as good as or better than the extensively used photocatalyst, titanium dioxide (TiO2). ZnO has paramount importance in photocatalysis due to its synthesis methods by which its morphology, crystal structure and optical properties can be tailored to extend the visible light absorption (Chen et al. Editorial Responsibility: R Saravanan. * S. Palaty [email protected] 1
Department of Chemistry, Bharata Mata College, Thrikkakara, Kochi, India
Department of Chemistry, Sree Sankara Vidyapeetom College, Valayanchirangara, India
2
2017; Alam et al. 2018; Duo et al. 2018). Despite the admirable traits of nano-ZnO such as high photosensitivity, versatile and low cost synthesis methods, photocatalysis suffers limitations such as high recombination rate of charge carriers and limited absorption in the visible light range (Kumari et al. 2015; Bazazi et al. 2018). Various strategies have been employed to overcome the limitations of ZnO photocatalyst such as doping with metals and non-metals, coupling with other semiconductors and carbon structures forming hetero junctions, enriching the defects and engineering the expos
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