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Application of Z–Scheme CdS - WO 3 Nanocomposite for Photodegradation of Ethylparaben under Irradiation with Visible Light: A Combined Experimental and Theoretical Study
Author(s) -
Ngigi Eric Mwangi,
Kiarii Ephraim Muriithi,
Nomngongo Philiswa Nosizo,
Ngila Catherine Jane
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201802136
Subject(s) - nanocomposite , photodegradation , bicarbonate , materials science , photocatalysis , catalysis , chemical engineering , degradation (telecommunications) , adsorption , nuclear chemistry , inorganic chemistry , photochemistry , chemistry , nanotechnology , organic chemistry , telecommunications , computer science , engineering
The CdS - WO 3 nanocomposite was successfully synthesized using the hydrothermal method. The catalytic capacity of CdS - WO 3 nanocomposite was evaluated based on various parameters, such as pH, catalyst load, bicarbonate and persulfate concentrations. The ratios of CdS to WO 3 was also examined to acquire the photocatalytic performance in addition, the by–products and pathway were also studied. The findings showed that CdS - WO 3 (ratio 3:7) produced better photodegradation performance in comparison to CdS - WO 3 (ratio 1:1). Also, from the same investigation, the CdS - WO 3 nanocomposite exhibited a slightly higher catalytic ability in the presence of 150 mg L –1 S 2 O 8 2– ions (at pH 3) than with bicarbonate ions. A 40% degradation was observed in the presence of 150 mg L –1 S 2 O 8 2– ions (at pH 3). Moreover, about 38% of adsorption was observed with bicarbonate ions. In this study, we systematically reveal the underlying mechanism of the improved photoactivity of CdS–WO 3 nanocomposite using a hybrid density functional theory calculation. The interfacial interaction led to the formation of a built–in internal electric field at the CdS–WO 3 interface to promote the separation of charge carriers, The theoretical results rationalise the experimental findings and offer a new understanding of the underlying mechanism of the photoactivity of CdS–WO 3 nanocomposite. The degradation pathway of Ethylparaben, which involved dealkylation of ethyl unit was proposed.