Copper Sulfide Based Heterojunctions as Photocatalysts for Dyes Photodegradation

Abstract

The presence of toxic, non-biodegradable and harmful organic pollutants in soils, wastewater, and atmosphere has become an indisputable, and global fact as a significant environmental problem. The heterogeneous photocatalysis, an advanced oxidation process (AOP) using semiconductor materials as catalysts, is a topic of great interest considering the possibility of the pollutants removal from water. The photocatalytic degradation of organic contaminants (i.e., dyes, pesticides, phenolic compounds) present in water using semiconductor materials depends on a number of parameters such as: the bandgap energy, phase composition, crystallinity, morphology and surface area of catalyst, electron-hole recombination rate, intensity of light, and adsorption capacity of the dye on the photocatalyst surface. One of the important constraints related to the catalyst photocatalytic efficiency is the fast recombination of the photogenerated electrons and holes. Therefore, various strategies have been involved in promoting the charge separation, including the development of heterojunction between two semiconductor materials, by tailoring the photocatalysts properties. This mini-review deals with the recent developments on dyes photodegradation using as catalysts various heterojunctions based on copper sulfide nanostructures, such as copper sulfide/metal oxide, copper sulfide/metal sulfide, copper sulfide/graphene, copper sulfide/organic semiconductors etc. The effects of different parameters, such as synthesis parameters, particle size, bandgap energy, surface area, and morphology on the photocatalytic activity of copper sulfide heterojunctions for dyes degradation is also highlighted.

Electrochemical Fingerprint of CuS-Hexagonal Chemistry from (Bis(N-1,4-Phenyl-N-(4-Morpholinedithiocarbamato) Copper(II) Complexes) as Photon Absorber in Quantum-Dot/Dye-Sensitised Solar Cells

“…This has emphasised the choice of semiconductors that could harvest the entire solar spectrum through their use as QD sensitisers. A major class of semiconductors consists of metal sulfide semiconductor-based photocatalysts that can alter size distribution without changing chemical constituents [16,17]. Copper monosulfide (CuS) has distinguished itself among metal sulfides owing to its different band gap and various morphologies.…”

In Situ Construction of CNT/CuS Hybrids and Their Application in Photodegradation for Removing Organic Dyes

“…Simultaneously, the photoexcited CNT is a good electron donor, readily leading to the migration of the photoexcited electrons in the LUMO of CNT to the CB of CuS. The interesting electron transfer process is somewhat similar to the Z-scheme charge mechanism (but different from the type II heterojunction [72]), and can efficiently prevent the recombination of the CB electrons with the VB holes in CuS. This is the dominant mechanism resulting in the enhanced photodegradation performance of the CNT/CuS composites compared to bare CuS.…”

Recent Advances in Zinc Oxide Nanostructures with Antimicrobial Activities

“…Certain conditions must be met for achieving improved photocatalytic activity of semiconductor heterostructures under visible light. There exists three types of coupled heterojunctions, i.e., type-I, type-II and type-III in terms of the alignment of their energy levels (Figure 10a) [181][182][183][184][185][186]. In type-I heterostructure, the CB and VB levels of the smaller bandgap semiconductor lie between those of a wider bandgap semiconductor.…”

“…The ZnO nanostructures produced include nanorods, nanoplates, nanoboxes, polyhedral drums and irregularly-shaped particles. Those nanostructures generally grow either along the <0001> or <1010> plane directions [186]. The ratio between the Zn vapor pressure and oxygen pressure, or the Zn/O flux ratio must be carefully monitored for attaining the desired ZnO nanostructures [187] [188].…”