High performance visible light response of a Z-type Bi2WO6/BiOBr/RGO heterojunction photocatalyst for the degradation of norfloxacin

A novel Bi12O17Cl2/GO/Co3O4 Z-type heterojunction photocatalyst with ZIF-67 derivative modified for highly efficient degradation of antibiotics under visible light

Levofloxacin (LVX) is difficult to be naturally degraded by microorganisms in water, and its residues in water will pose significant risks to human health and ecological environment. In this study, Bi12O17Cl2 was used as the main body, Bi12O17Cl2/GO/Co3O4 composite photocatalyst was prepared by pyrolysis of zeolitic imidazolate framework-67 (ZIF-67) combined with in-situ precipitation method and used to degrade LVX. A sequence of characterizations shows that addition of Co3O4 and graphene oxide (GO) increases the visible light response range, improves the separation efficiency of photogenerated electrons and holes (e--h+) of photocatalyst, and thus improves the degradation efficiency of LVX. Under the optimal reaction conditions, the LVX degradation rate of Bi12O17Cl2/1.5GO/7.5Co3O4 can reach 91.2 % at 120 min, and its reaction rate constant is the largest (0.0151 min-1), which is 2.17, 13.14 and 1.53 times that of Bi12O17Cl2, Co3O4 and Bi12O17Cl2/7.5Co3O4, respectively, showing better photocatalytic performance. Simultaneously, the recycling stability of Bi12O17Cl2/1.5GO/7.5Co3O4 was also verified. The capture experiments and electron EPR test results showed that superoxide radicals (•O2-) and photogenerated holes (h+) were the primary active substances in the reaction process. Finally, combined with HPLC-MS results, the photocatalytic degradation pathway of LVX was derived. This work will provide a theoretical basis for the design of Metal Organic Frameworks (MOFs)-derivative modified Bi12O17Cl2-based photocatalysts.

Floatable Cu2(OH)PO4/rGO Aerogel for Full Spectrum Driven Photocatalytic Degradation of Organic Pollutants

Photocatalytic technology is an attractive option for environmental remediation because of its green and sustainable nature. However, the inefficient utilization of solar energy and powder morphology currently impede its practical application. Here, we designed a floatable photocatalyst by anchoring 0D Cu2(OH)PO4 (CHP) nanoparticles on 2D graphene to construct 0D/2D CHP/reduced graphene oxide (rGO) aerogels. The CHP/rGO aerogels have interconnected mesopores that provide a large surface area, promoting particle dispersion and increasing the number of active sites. Moreover, the optical response of the CHP/rGO aerogel has been significantly expanded to cover the full spectrum of the solar light. Notably, the 20%CHP/rGO aerogel displayed a high degradation rate (k = 0.178 min-1) taking methylene blue (MB) as a model pollutant under light irradiation (λ > 420 nm). The enhanced photocatalytic activity is ascribed to the rapid electron transfer in the CHP/rGO heterostructures, as supported by the DFT theoretical calculations. Our research highlights the utilization of full spectrum responsive photocatalysts for the elimination of organic pollutants from wastewater under solar light irradiation, as well as the potential for catalyst recovery using floatable aerogels to meet industrial requirements.

Coupling Z-Scheme g-C3N4/rGO/MoS2 Ternary Heterojunction as an Efficient Visible Light Photocatalyst for Hydrogen Evolution and RhB Degradation

Coupling heterostructures to synergistically improve the light adsorption and promote the charge carrier separation has been regarded as an operative approach to advance the photocatalytic performances. However, it is still challenging to construct heterostructures with appropriate optical properties and interfacial energy structures at the same time. In this work, a Z-scheme g-C3N4/rGO/MoS2 ternary composite photocatalyst is successfully synthesized via an effective hydrothermal method. The as-synthesized g-C3N4/rGO/MoS2 composite photocatalyst exhibited significant improvement for visible light absorption and boosted the separation efficiency of photoinduced electron-hole pairs. The g-C3N4/rGO/MoS2 system exhibited optimum visible-light-induced photocatalytic activity in hydrogen (H2) from water splitting and degrading pollutant rhodamin B (RhB), which is 22 times and 5 times higher than that of pure g-C3N4, respectively. The excellent photocatalytic activities are attributed to the synergetic effects of coupling rGO, g-C3N4, and MoS2 ternary structures to the composite photocatalyst. These combinations of intimate two-dimensional nanoconjugations can effectively inhibit charge recombination and accelerate charge transfer kinetics, forming a Z-scheme-assisted photocatalytic mechanism, thereby exhibiting superior photocatalytic activity.

Recent Progress in Photocatalytic Degradation of Water Pollution by Bismuth Tungstate

Photocatalysis has emerged as a highly promising, green, and efficient technology for degrading pollutants in wastewater. Among the various photocatalysts, Bismuth tungstate (Bi2WO6) has gained significant attention in the research community due to its potential in environmental remediation and photocatalytic energy conversion. However, the limited light absorption ability and rapid recombination of photogenerated carriers hinder the further improvement of Bi2WO6's photocatalytic performance. This review aims to present recent advancements in the development of Bi2WO6-based photocatalysts. It delves into the photocatalytic mechanism of Bi2WO6 and summarizes the achieved photocatalytic characteristics by controlling its morphology, employing metal and non-metal doping, constructing semiconductor heterojunctions, and implementing defective engineering. Additionally, this review explores the practical applications of these modified Bi2WO6 photocatalysts in wastewater purification. Furthermore, this review addresses existing challenges and suggests prospects for the development of efficient Bi2WO6 photocatalysts. It is hoped that this comprehensive review will serve as a valuable reference and guide for researchers seeking to advance the field of Bi2WO6 photocatalysis.

Iron doped BiOBr loaded on carbon spheres for improved visible-light-driven detoxification of 2-chloroethyl sulfide

In this study, flower-like porous iron doped bismuth oxybromide on porous activated carbon visible light catalysts (BiOBr/Fe@AC) were prepared by a reactive imidazole ionic liquid surfactant assisted solvothermal process. The morphologies, structures, optical properties and photocatalytic properties were investigated in detail. The morphology of the synthesized Fe doped BiOBr composites gradually changed from a regular spherical shape to a non-specific shape with the increase of the alkyl chain length of the ionic liquid surfactants. The photocurrent of BiOBr/Fe@AC composites is greatly influenced by the content of Fe, the type of carbon sphere and the size of the composites. The photocatalytic activity of the obtained BiOBr/Fe@AC composites was evaluated by the degradation of 2-chloroethyl sulfide (CEES) under visible light. The BiOBr/Fe@AC composites exhibited significantly enhanced photocatalytic performance compared to that of pure BiOBr and the 10.0% Fe doped BiOBr/Fe@AC composite displayed the highest photocatalytic activity. The main active species were determined to be holes and superoxide radicals by electron spin resonance (ESR) analysis and free radical trapping experiments. The introduction of iron can improve the separation and transfer rate of photoinduced charges. Carbon spheres can enhance light harvesting, improve electron transfer and increase the number of catalytic active sites. Iron and carbon embellishment is an effective strategy to enhance the photocatalytic efficiency of BiOBr. Finally, a possible photocatalytic mechanism of BiOBr/Fe@AC has been proposed.