Bi and oxygen defects improved visible light photocatalysis with BiOBr nanosheets

Recent advances on bismuth oxyhalides for photocatalytic CO2 reduction

Photocatalytic conversion of CO2 into fuels such as CO, CH4, and CH3OH, is a promising approach for achieving carbon neutrality. Bismuth oxyhalides (BiOX, where X = Cl, Br, and I) are appropriate photocatalysts for this purpose due to the merits of visible-light-active, efficient charge separation, and easy-to-modify crystal structure and surface properties. For practical applications, multiple strategies have been proposed to develop high-efficiency BiOX-based photocatalysts. This review summarizes the development of different approaches to prepare BiOX-based photocatalysts for efficient CO2 reduction. In the review, the fundamentals of photocatalytic CO2 reduction are introduced. Then, several widely used modification methods for BiOX photocatalysts are systematacially discussed, including heterojunction construction, introducing oxygen vacancies (OVs), Bi-enrichment, heteroatom-doping, and morphology design. Finally, the challenges and prospects in the design of future BiOX-based photocatalysis for efficient CO2 reduction are examined.

Enhanced visible light photocatalytic performance of a novel FeIn2S4 microsphere/BiOBr nanoplate heterojunction with a Z-scheme configuration

The rational design of heterojunction photocatalysts is an effective way to improve semiconductor photocatalytic activity. The simple solvothermal method was used to successfully prepare visible light-driven FeIn₂S₄ microsphere/BiOBr nanoplate binary heterojunction photocatalysts with varying FeIn₂S₄ contents. The crystal structure, morphology, surface composition, specific surface area, charge separation, and optical properties of the as-prepared photocatalysts were investigated using a variety of analytical methods. In the photocatalytic degradation of rhodamine B, the FeIn₂S₄/BiOBr photocatalysts obtained a degradation efficiency of 96% within 60 min, which was approximately 5.33 and 2.59 times higher than pure FeIn₂S₄ and BiOBr, respectively. Radical trapping experiments and ESR measurements revealed the main active species (·OH, ·O₂^-, and h⁺) produced during photocatalytic degradation. The increased photocatalytic activity was due to the formation of Z-scheme heterojunctions between FeIn₂S₄ and BiOBr, which contributed to the improved effective charge separation of photogenerated charge carriers, augmented specific surface area, and enhanced redox capacity. It is expected that our current study will provide a hopeful way for future environmental remediation research.

Bi@BiOx(OH)y modified oxidized g-C3N4 photocatalytic removal of tetracycline hydrochloride with highly effective oxygen activation

A novel Bi@BiOx(OH)y-modified oxidized g-C₃N₄ photocatalyst was successfully prepared via wet chemical reduction under alkaline conditions for the tetracycline hydrochloride removal. The prepared materials were characterized comprehensively and fully. Sufficient structural representation analyses confirmed the successful loading of Bi in the form of Bi@BiOx(OH)y complex beads. Based on basic photocatalytic studies, 10% (mass percentage) was found to be the best metal Bi loading. DRS, PL, transient photocurrent and EIS have explored the improvement of the photochemical properties of materials by loading Bi@BiOx(OH)y groups, particularly the improvement of photocatalytic properties by the SPR effect and electron traps. 10%Bi-OxCN exhibited the most suitable particle size of nonagglomerated Bi-metal groups, the largest specific surface area (43.53 m² g^-1), the most adsorption sites and the most significant photocurrent (8.694 × 10^-2 mA cm^-2) (7.78 times that of OxCN). This indicated that 10%Bi-OxCN had good adsorption capacity and excellent light response capability. In addition, 10%Bi-OxCN showed the best tetracycline hydrochloride removal efficiency (96.0%), with ∙O₂^- as the main active substance and ¹O₂ as the second most important substance made of ∙O₂^- and h⁺. The excellent photocatalytic effect and good reusability were fundamentally dependent on the modification of OxCN by Bi@BiOx(OH)y groups to produce a large number of active substances (including the separation efficiency of electron-hole pairs and the generation efficiency of ∙O₂^- and ¹O₂). These advantages are all related to the high specific surface area, a large number of active sites, narrow bandgap width, Bi-SPR effect, and BiOx(OH)y electron trap caused by successful loading of Bi groups.