Ternary CdS/MoS 2 /ZnO Photocatalyst: Synthesis, Characterization and Degradation of Ofloxacin Under Visible Light Irrad
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Ternary CdS/MoS2/ZnO Photocatalyst: Synthesis, Characterization and Degradation of Ofloxacin Under Visible Light Irradiation Ali İmran Vaizoğullar1 Received: 26 March 2020 / Accepted: 25 April 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Ternary CdS/MoS2/ZnO (CMZ) photocatalyst was prepared that successfully degraded ofloxacin antibiotic under visible light irradiation. SEM mapping analyses of CMZ showed homogenous elemental distribution. The XRD analysis shows that ternary composites contained ZnO in the hexagonal wurtzite, CdS in cubic phase and MoS2 in the hexagonal structure. UV-DRS results of CMZ exhibited thresholds of ~ 430 nm. The photocatalytic degradation studies were performed with ofloxacin antibiotic (290 nm) under visible light irradiation. BET results presented Type III isotherm and H3 hysteresis. Ternary CMZ showed higher photoelectrochemical and photocatalyic activity due to prolonged lifetime of charge it carries, crystalline defect and surface plasmon resonance of CdS. The kinetic rate constant of ternary CMZ was 4 times higher than that of CdS/MoS2 (CM). This study presents an effective photocatalysis and the mechanism of ofloxacin degradation by CMZ ternary composite heterojunction. Keywords Ternary composites · Ofloxacin · ZnO/MoS2 · CdS/MoS2 · Photocatalytic degradation
1 Introduction The use of semiconductors in the photocatalytic degradation of organic wastewater pollutants and water splitting is attracting the attention of the scientists. However, it is difficult to use semiconductors in each application such as the production of hydrogen gas by splitting water, conversion of CO2, gas sensors, decomposition of organic pollutants [1] etc. To improve the photocatalytic performance of a catalyst that enhances the separation of charge carriers, appropriate co-catalysts can be used [2]. CdS is an II-IV promising semiconductor photocatalysis. Additionally, CdS has high photocatalytic activity and absorb wide range of visible light with narrow band gap [~ 2.2 eV] [3]. However, the oxidation of photo-generated holes, which causes photo-corrosion of CdS, results in poor stability in aqueous solutions [4]. In addition, CdS is an important metal sulfide that provides superior quality hetero composite with MoS2 [5]. The prepared hybrid structures of Cd based composites enhance * Ali İmran Vaizoğullar [email protected] 1
Vocational School of Health Care, Medical Laboratory Programme, Muğla Sıtkı Koçman University, 48000 Muğla, Turkey
the catalytic properties. For example, the homogeneous distribution of catalyst components can be effective in the adsorption and stimulation of active sites. Synergistic effect between components plays a major role in the formation of different electronic arrangements [6]. In crystalline MoS2, Mo atoms are inserted into two sulfur atom, which is well known as a perfect photocatalyst. It also enhances the photocatalytic performance of co-catalysis. The M oS2 can be used as an auxiliary catalyst by producing more superox
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