Highly efficient photocatalytic activities, band alignment of BiVO4/BiOCl {001} prepared by in situ chemical transformation

Deep-Eutectic-Solvent-Assisted Synthesis of a Z-Scheme BiVO4/BiOCl/S,N-GQDS Heterojunction with Enhanced Photocatalytic Degradation Activity under Visible-Light Irradiation

Z-scheme heterojunction photocatalytic nanomaterial designs have attracted attention due to their high catalytic performance. Deep eutectic solvents (DESs) have been used as green, sustainable media, acting as solvents and structure inducers in the synthesis of nanomaterials. In this work, a novel visible-light-absorption-enhanced bismuth vanadate/bismuth oxychloride/sulfur, nitrogen co-doped graphene quantum dot (BiVO₄/BiOCl/S,N-GQDS) heterojunction photocatalyst was prepared in a deep eutectic solvent. The photosynthetic activity of the BiVO₄/BiOCl/S,N-GQDS composite was determined by the photocatalytic degradation of rhodamine B (RhB) under visible-light irradiation. The results showed that the highest photocatalytic activity of BiVO₄/BiOCl/S,N-GQDS was achieved when the doping amount of S,N-GQDS was 3%, and the degradation rate of RhB reached 70% within 5 h. The kinetic and photocatalytic cycles showed that the degradation of Rhb was in accordance with the quasi-primary degradation kinetic model, and the photocatalytic performance remained stable after four photocatalytic cycles. Ultraviolet-visible diffuse reflectance (UV-DRS) and photoluminescence (PL) experiments confirmed that BiVO₄/BiOCl/S,N-GQDS ternary heterojunctions have a narrow band gap energy (2.35 eV), which can effectively improve the separation efficiency of the photogenerated electron-hole pairs and suppress their complexation. This is due to the construction of a Z-scheme charge process between the BiVO₄/BiOCl binary heterojunction and S,N-GQDS, which achieves effective carrier separation and thus a strong photocatalytic capability. This work not only provides new insights into the design of catalysts using a green solvent approach but also provides a reference for the study of heterojunction photocatalytic materials based on bismuth vanadate, as well as new ideas for other photocatalytic materials.

Advances in facet-dependent photocatalytic properties of BiOCl catalyst for environmental remediation

Bismuth chloride oxide (BiOCl) is a typical V-VI-VII ternary oxide material, which is one of the widely studied metal oxides due to its unique surface, electronic and photocatalytic properties. However, the broad bandgap and the large number of photogenerated electron-hole pair complexes of BiOCl limit its photocatalytic efficiency. Since the photocatalytic performance of BiOCl is highly dependent on its exposed crystallographic facets, research attention has increasingly focused on the different structures and properties possessed by different crystallographic facets of BiOCl. This article reviews the basic principles of using different crystalline surfaces of BiOCl materials to enhance photocatalytic activity, summarizes the applications of BiOCl single-crystal catalysts and composite catalysts in the environmental field, and provides an outlook on the challenges and new research directions for future development in this emerging frontier area. It is hoped that the crystalline surface-related photocatalysis of BiOCl can be used to provide new guidance for the rational design of novel catalysts for various energy and environment-related applications.

Construction of a Bioinspired Hierarchical BiVO4/BiOCl Heterojunction and Its Enhanced Photocatalytic Activity for Phenol Degradation

Development of a p-n heterojunction to achieve efficient degradation of organic pollutants is a promising approach in the field of photocatalysis. Herein, BiVO₄ with bioinspired hierarchical structures was prepared with the sol-gel method and combined with BiOCl nanoplates to construct a 3D/2D configuration via an in situ deposition route. The hierarchical BiVO₄ served as an excellent substrate to achieve the uniform loading of BiOCl nanoplates. The obtained 3D/2D BiVO₄/BiOCl hybrids exhibited significantly enhanced photocatalytic efficiency for degrading phenol under visible light irradiation, with a first-order reaction rate constant that was 9.9 and 1.9 times higher than those of hierarchical BiVO₄ and the BiVO₄/BiOCl hybrids without hierarchical structures, respectively. Moreover, the hierarchical BiVO₄/BiOCl also displayed good photochemical stability for the degradation of phenol after three recycles. The p-n heterojunction and hierarchical structure worked together to form a spatial conductive network framework, which possessed improved visible light absorption, high specific surface area, as well as effective separation and transfer of photogenerated charge carriers.

One-Pot Synthesized Visible Light-Driven BiOCl/AgCl/BiVO4 n-p Heterojunction for Photocatalytic Degradation of Pharmaceutical Pollutants

A novel enhanced visible light absorption BiOCl/AgCl/BiVO₄ heterojunction of photocatalysts could be obtained through a one-pot hydrothermal method used with two different pH solutions. There was a relationship between synthesis pH and the ratio of BiOCl to BiVO₄ in XRD planes and their photocatalytic activity. The visible light photocatalytic performances of photocatalysts were evaluated via degradation of diclofenac (DCFF) as a pharmaceutical model pollutant. Furthermore, kinetic studies showed that DCF degradation followed pseudo-first-order kinetics. The photocatalytic degradation rates of BiOCl/AgCl/BiVO₄ synthesized at pH = 1.2 and pH = 4 for DCF were 72% and 47%, respectively, showing the higher activity of the photocatalyst which was synthesized at a lower pH value. It was concluded that the excellent photocatalytic activity of BiOCl/AgCl/BiVO₄ is due to the enhanced visible light absorption formation of a heterostructure, which increased the lifetime of photo-produced electron–hole pairs by creating a heterojunction. The influence of pH during synthesis on photocatalytic activity in order to create different phases was investigated. This work suggests that the BiOCl/AgCl/BiVO₄ p-n heterojunction is more active when the ratio of BiOCl to BiVO₄ is smaller, and this could be achieved simply by the pH adjustment. This is a promising method of modifying the photocatalyst for the purpose of pollutant degradation under visible light illumination.

An α-Bi2O3/BiOBr core–shell heterojunction with high photocatalytic activity

We prepared α-Bi₂O₃/BiOBr core–shell heterojunction via a facile in situ chemical transformation method. The prepared α-Bi₂O₃/BiOBr photocatalyst is characteristic of porous and high specific surface area, and shows high photocatalytic activity.

In situ chemical transformation synthesis of Bi4Ti3O12/I–BiOCl 2D/2D heterojunction systems for water pollution treatment and hydrogen production

Enhancing visible light response and inhibiting the recombination of photogenerated charge carriers are vital for Bi₄Ti₃O₁₂ nanosheets to achieve high activity in the fields of hydrogen generation and water pollutant treatment.