Novel Type-II Heterojunction Binary Composite (CdS/AgI) with Outstanding Visible Light-Driven Photocatalytic Performances toward Methyl Orange and Tetracycline Hydrochloride

Abstract

In this study, an effective type-II heterojunction CdS/AgI binary composite was constructed by an in situ precipitation approach. To validate the successful formation of heterojunction between AgI and CdS photocatalysts, the synthesized binary composites were characterized by various analytical techniques. UV−vis diffuse-reflectance spectroscopy (UV−vis DRS) revealed that heterojunction formation led to a red shift in the absorbance spectra of the CdS/AgI binary composite. The optimized 20AgI/CdS binary composite showed a least intense photoluminescence (PL) peak indicating highly improved charge carrier (e − /h + pairs) separation efficiency. The photocatalytic efficiency of the synthesized materials was assessed based on the degradation of methyl orange (MO) and tetracycline hydrochloride (TCH) in the presence of visible light. Compared to bare photocatalysts and other binary composites, the 20AgI/CdS binary composite showed the highest photocatalytic degradation performances. Additionally, the trapping studies showed that superoxide radical anion (O 2•− ) was the most dominant active species involved in photodegradation processes. Based on the results of active species trapping studies, a mechanism was proposed to describe the formation of type-II heterojunctions for CdS/AgI binary composite. Overall, the synthesized binary composite has tremendous promise for environmental remediation due to its straightforward synthesis approach and excellent photocatalytic efficacy.

A floating photocatalytic fabric integrated with a AgI/UiO-66-NH2 heterojunction as a facile strategy for wastewater treatment

“…2a-d). 40,52 It is noted that the offset of binding energy represents the change of surface charge density; for example, an increase in the binding energy suggests the reduced electron density. 40 In this analysis, it is speculated that the changes of electron density in hybrid materials result from the formation of heterojunction.…”

La/Fe bimetallic MOF-derived p-LaFeO3/n-CdS heterojunction: efficient photocatalytic degradation of organic contaminants and adsorption isotherms

“…Simultaneously, the holes in the VB of LaFeO 3 moved to the VB of CdS, interacted with the contaminants directly and converted into degraded products. The holes are unable to convert into the hydroxyl radicals ( OH) on reaction with H 2 O, because the redox potential of CdS (+1.68) is less positive than the OH/OH À potential (+2.38 eV vs. NHE) 65 and the H 2 O/ OH potential (+2.71 eV vs. NHE). 66 Consequently, the formation of electron-hole (e À /h + ) pairs in the LaFeO 3 /CdS is expected to result in the construction of a heterojunction between LaFeO 3 and CdS.…”

Recent Progress on Semiconductor Heterogeneous Photocatalysts in Clean Energy Production and Environmental Remediation

“…Among conventional heterojunctions, type-II heterojunction is the most suitable structure for designing high-performance photocatalysts owing to its improved charge separation and transmission. Ahmad et al fabricated [160] AgI/CdS binary composite via an in situ precipitation method and examined its performance for photodegradation of methyl orange (MO) and tetracycline hydrochloride (TCH) under visible light illumination. The as-prepared photocatalyst showed high efficiency of 94.5 and 91% for MO and TCH degradation, respectively.…”