Ionic liquid induced mechanochemical synthesis of BiOBr ultrathin nanosheets at ambient temperature with superior visible-light-driven photocatalysis

Photocatalytically self-cleaning graphene oxide nanofiltration membranes reinforced with bismuth oxybromide for high-performance water purification

Graphene oxide (GO) membranes have emerged as promising candidates for water purification applications, owing to their unique physicochemical attributes. Nevertheless, the trade-off between permeability and selectivity, coupled with their vulnerability to membrane fouling, poses significant challenges to their widespread industrial deployment. In this study, we introduce an innovative in-situ growth and layer-by-layer assembly technique for fabricating multilayer GO membranes reinforced with bismuth oxybromide (BiOBr) on commonly employed Nylon substrates. This method allows for the creation of two-dimensional lamellar membranes capable of photocatalytic self-cleaning and tunable nanochannel dimensions. The synthesized GO/BiOBr composite membranes exhibit remarkable water permeance rates (approximately 493.9 LMH/bar) and high molecular rejection efficiency (>99 % for Victoria Blue B and Congo Red dyes). Notably, these membranes showcase an enhanced photocatalytic self-cleaning performance upon exposure to visible light. Our work provides a viable route for the fabrication of functionalized GO-based nanofiltration membranes with BiOBr inclusions, offering a synergistic combination of high water permeability, modifiable nanochannels, and effective self-cleaning capabilities through photocatalysis.

A review on the progress of the photocatalytic removal of refractory pollutants from water by BiOBr-based nanocomposites

Organic matters from various sources such as the manufacturing, agricultural, and pharmaceuticals industries is continuously discharged into water bodies, leading to increasingly serious water pollution. Photocatalytic technology is a clean and green advanced oxidation process, that can successfully decompose various organic pollutants into small inorganic molecules such as carbon dioxide and water under visible light irradiation. Bismuth oxybromide (BiOBr) is an attractive visible light photocatalyst with good photocatalytic performance, suitable forbidden bandwidth, and a unique layered structure. However, the rapid combination of the electron-hole pairs generated in BiOBr leads to low photocatalytic activity, which limits its photocatalytic performance. Due to its unique electronic structure, BiOBr can be coupled with a variety of different functional materials to improve its photocatalytic performance. In this paper, We present the morphologically controllable BiOBr and its preparation process with the influence of raw materials, additives, solvents, synthesis methods, and synthesis conditions. Based on this, we propose design synthesis considerations for BiOBr-based nanocomplexes in four aspects: structure, morphology and crystalline phase, reduction of electron-hole pair complexation, photocorrosion resistance, and scale-up synthesis. The literature on BiOBr-based nanocomposites in the last 10 years (2012-2022) are summarized into seven categories, and the mechanism of enhanced photocatalytic activity of BiOBr-based nanocomposites is reviewed. Moreover, the applications of BiOBr-based nanocomposites in the fields of degradation of dye wastewater, antibiotic wastewater, pesticide wastewater, and phenol-containing wastewater are reviewed. Finally, the current challenges and prospects of BiOBr-based nanocomposites are briefly described. In general, this paper reviews the construction of BiOBr-based nanocomposites, the mechanism of photocatalytic activity enhancement and its research status and application prospects in the degradation of organic pollutants.

Polyvinyl pyrrolidone-coordinated ultrathin bismuth oxybromide nanosheets for boosting photoreduction of carbon dioxide via ligand-to-metal charge transfer

Photoreduction of CO₂ to useful ingredients remains a great challenge due to the high energy barrier of CO₂ activation and poor product selectivity. Herein, Polyvinyl pyrrolidone (PVP) coordinated BiOBr was synthesized by a facile chemical precipitation method at room temperature. The CO₂ photoreduction behaviors of PVP coordinated BiOBr were evaluated with H₂O without sacrificial agent under the simulated sunlight. The evolution rates of CO and CH₄ are 263.2 µmol g^-1h^-1 and 3.3 µmol g^-1h^-1, which are 8 times and 2 times higher than those of pure BiOBr respectively. Furthermore, the coordination of PVP on BiOBr surface enhances greatly the selectivity of product CO, which is close to 100%. Loading PVP onto BiOBr could not only induce and stabilize the oxygen vacancy, but also increase the charge density of BiOBr via the ligand to metal charge transfer (LMCT), which could be beneficial to the adsorption and activation of CO₂ molecule. The photoreduction mechanism of CO₂ for PVP coordinated BiOBr was proposed based on the improved charge density of BiOBr by the experimental results and Density functional theory (DFT) calculations. This finding provides a new pathway to boost the conversion efficiency and selectivity for the activation of CO₂ photoreduction and new molecule insights into the role of PVP in photocatalysis.

Doping and facet effects synergistically mediated interfacial reaction mechanism and selectivity in photocatalytic NO abatement

The surface atomic coordination and arrangement largely determine photocatalytic properties. Whereas, the intrinsic impact of surface microstructures on the reaction mechanism and pathway is still unclear. Herein, via constructing N-doped Bi₂O₂CO₃ photocatalysts with diverse exposed facets, (1 1 0) and (0 0 1) facet, we testify that the pivotal roles of crystal facet and doping effect on the intermediate production and reactivity for photocatalytic nitric oxide (NO) abatement. The photoreactivity of N-doped Bi₂O₂CO₃ is documented to be higher than that of the pure samples because of the enhanced light absorption and charge transfer. Further in situ probing experiments and theoretical calculations verify that the unique adsorption patterns and activated intermediates on the (1 1 0) facet facilitate the formation of final products and inhibit the generation of toxic NO₂ by-product in terms of thermodynamics. More importantly, we found that the selective and nonselective oxidation processes are emerged over (1 1 0) and (0 0 1) facets of Bi₂O₂CO₃, respectively.

Oriented construction of S-doped, exposed {001} facet BiOBr nanosheets with abundant oxygen vacancies and promoted visible-light-driven photocatalytic performance

S-doping orients the facet growth of BiOBr nanosheets from original exposed {010} plane towards {001}-dominant plane, resulting in narrower bandgap energy, higher efficient charges separation and oxygen vacancies (OVs) concentration.