Ternary Z-Scheme Heterojunction of Bi2WO6 with Reduced Graphene Oxide (rGO) and Bi25FeO40 for Enhanced Visible-Light Photocatalysis

Design of Z-scheme g-C3N4/BC/Bi25FeO40 photocatalyst with unique electron transfer channels for efficient degradation of tetracycline hydrochloride waste

High electron transfer rates and a higher number of electron transfer active sites play important roles in inhibiting the recombination of photogenerated electron-hole pairs. In the experiments described in this article, the g-C₃N₄/BC/Bi₂₅FeO₄₀ composite material was prepared to use biochar (BC) as the conductive channel. The presence of BC significantly increases the electron transfer rate due to its excellent electrical conductivity and can provide more electron transfer active sites. At the same time, BC provides a larger surface area and has a loose porous structure, which lead to excellent adsorption performance. Based on various characterization results, it was confirmed that the Z-scheme heterojunction was successfully constructed between g-C₃N₄ and Bi₂₅FeO₄₀. The photocatalytic experiment results showed that the degradation efficiency of g-C₃N₄/BC/Bi₂₅FeO₄₀ on the tetracycline hydrochloride (TCH) could reach 92.2% within 60 min. Parameters such as circulation stability, pH value of the solution and the amount of composite materials were studied. The synthesized composite material has good reusability and high efficiency in a wide pH range of 3-11. Its excellent photocatalytic activity is attributed to the formation of an effective Z-scheme heterostructure, as well as the rapid photoelectron transfer and excellent adsorption capacity of BC. This work provides a way to design new photocatalysts using semiconductor composite materials and BC materials.

Recent advances in degradation of pharmaceuticals using Bi2WO6 mediated photocatalysis - A comprehensive review

The pollution of water bodies by residual pharmaceuticals is a major problem globally. Bismuth tungstate mediated photocatalysis has been effective in the removal of these organics from water. Bismuth tungstate (Bi₂WO₆) has proven to be an excellent visible light active photocatalyst because of its non-toxicity, low band gap energy and ease of preparation. It has been widely applied for the removal of a wide array of organic pollutants, particularly dyes, from wastewater. However, recently, much attention has been channelled to its application for the degradation of pharmaceuticals. In this present review, the recent trends in the applications of Bi₂WO₆ based photocatalysts for the removal of pharmaceuticals in wastewater are comprehensively discussed. The fabrication of Bi₂WO₆ based photocatalysts with enhanced photocatalytic performances through morphology control, doping and formation of heterojunctions are highlighted. Much discussion centres on the mechanisms and possible degradation pathways of antibiotic pharmaceuticals in wastewater. Finally, areas needing more attention and investigation on the use of Bi₂WO₆ based photocatalysts for removal of pharmaceuticals from wastewater especially towards real-life applications are presented for future research directions.

Photocatalytic reduction of 4-nitroaniline in aqueous solution using BiOCl/BiOBr/rGO ternary heterojunction under simulated UV-visible light irradiation

BiOCl/BiOBr/rGO ternary heterojunctions were synthesized and characterized, and their photocatalytic activities were examined. Three different rGO mass ratios were incorporated into BiOCl_75%BiOBr_25%; 1% rGO, 3% rGO, and 5% rGO, respectively. The successful incorporation of rGO into the composites was confirmed using powder X-ray diffraction (PXRD). Furthermore, calculated band gap, elemental composition, and composites' morphology were investigated using UV-visible (UV-Vis) diffuse reflectance spectroscopy (DRS), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM), respectively. The photocatalytic activities of the ternary heterojunctions were evaluated toward the photocatalytic reduction of 4-nitroaniline (4-NA) in aqueous solution. Experimental results reveal that rGO incorporation enhances the activity of the prepared heterojunction photocatalysts, where photocatalyst containing 5% rGO exhibited the highest activity achieving rate of 0.84 min^-1.

Review on the Visible Light Photocatalysis for the Decomposition of Ciprofloxacin, Norfloxacin, Tetracyclines, and Sulfonamides Antibiotics in Wastewater

Antibiotics are chemical compounds that are used to kill or prevent bacterial growth. They are used in different fields, such as the medical field, agriculture, and veterinary. Antibiotics end up in wastewater, which causes the threat of developing antibacterial resistance; therefore, antibiotics must be eliminated from wastewater. Different conventional elimination methods are limited due to their high cost and effort, or incomplete elimination. Semiconductor-assisted photocatalysis arises as an effective elimination method for different organic wastes including antibiotics. A variety of semiconducting materials were tested to eliminate antibiotics from wastewater; nevertheless, research is still ongoing due to some limitations. This review summarizes the recent studies regarding semiconducting material modifications for antibiotic degradation using visible light irradiation.