ZIF-8 incorporated CeO2-CdS quantum dots @ 2D g-C3N4 nanosheets as a staggered type II heterojunction for decolouration of a set of dyes

Abstract

Dye toxins, emitted by industries, pose a significant threat to living beings and aquatic life by absorbing light radiation and inhibiting the growth of essential bacteria and microbes, making their removal crucial for health of living beings and flora and fauna. This research endorsed a hydrothermal synthetic route for the photocatalyst CeO2/CdS/g-C3N4 @ZIF8 (or CCdGZ) fabrication to remove a set of hazardous dyes from wastewater streams. Corresponding Analytical methods evaluated the successfully developed CCdGZ photocatalyst's structural, morphological, and compositional properties. Powder X-ray photoelectron (PXRD) analysis showed the structural properties of CCdGZ and the quantum dot nature of the CeO2-CdS hybrid in the heterostructure with a crystallite size of 0.16 nm. The photocatalyst's optical responses were examined using UV–vis spectrophotometry and the UV-diffuse reflectance spectroscopy (UV-DRS) technique. Tauc's plot determined the energy band gap of the CCdGZ to be ∼2.64 eV, confirming a slight modification of the valence band (VB) and conduction band (CB) edges of the moieties CeO2, CdS, and g-C3N4. Thus, the heterostructure's moieties synergised to produce photocatalytic degradation. Under visible light irradiation, the photocatalyst CCdGZ photodegraded Victoria blue R (VBR) dye by 96.54% in 55 min. Photodegradation followed pseudo-first-order kinetics with a specific reaction rate of 0.06159 min−1 {coefficient of determination (R2) = 0.99847}. The corresponding TOC removal was 83.27%, while COD got reduced to 78.98% of its initial magnitude. Multiple reaction parameters, heterostructure reusability (over 89% efficient till the 5th run), the scavengers' experiment, inorganic ion effects, and water matrices were also evaluated. The study concludes with a photocatalytic reaction mechanism that explains the moieties' roles. This study designs a heterostructure photocatalyst that disintegrates emerging non-degradable organic pollutants in the UV–visible range, is recoverable, and has better photostability.