Insight into the photocatalytic mechanism of the optimal x value in the BiOBrxI1-x, BiOClxI1-x and BiOClxBr1-x series varying with pollutant type

Visible-Light-Active Iodide-Doped BiOBr Coatings for Sustainable Infrastructure

The search for efficient materials for sustainable infrastructure is an urgent challenge toward potential negative emission technologies and the global environmental crisis. Pleasant, efficient sunlight-activated coatings for applications in self-cleaning windows are sought in the glass industry, particularly those produced from scalable technologies. The current work presents visible-light-active iodide-doped BiOBr thin films fabricated using aerosol-assisted chemical vapor deposition. The impact of dopant concentration on the structural, morphological, and optical properties was studied systematically. The photocatalytic properties of the parent materials and as-deposited doped films were evaluated using the smart ink test. An optimized material was identified as containing 2.7 atom % iodide dopant. Insight into the photocatalytic behavior of these coatings was gathered from photoluminescence and photoelectrochemical studies. The optimum photocatalytic performance could be explained from a balance between photon absorption, charge generation, carrier separation, and charge transport properties under 450 nm irradiation. This optimized iodide-doped BiOBr coating is an excellent candidate for the photodegradation of volatile organic pollutants, with potential applications in self-cleaning windows and other surfaces.

Facile construction of photocatalytic cellulose-based sponge with stable flotation properties as efficient and recyclable photocatalysts for sewage treatment

Dispersion and recycling of powdered nano-photocatalysts for water purification is still not an easy task. The self-supporting and floating photocatalytic cellulose-based sponges ware conveniently prepared by anchoring BiOX nanosheet arrays on cellulose-based sponge's surface. The introduction of sodium alginate into the cellulose-based sponge significantly enhanced the electrostatic adsorption of bismuth oxygen ions and promoted the formation of bismuth oxyhalide (BiOX) crystal nuclei. Among the photocatalytic cellulose-based sponges, the sponge (BiOBr-SA/CNF) modified with bismuth oxybromide displayed excellent photocatalytic ability for photodegrading 96.1 % rhodamine B within 90 min under 300 W Xe lamp irradiation (λ > 400 nm). The loading of bismuth oxybromide on cellulose-based sponge's surface improves the flotation stability of the cellulose-based sponge. Benefiting from excellent load fastness of bismuth oxybromide nanosheet and flotation stability of BiOBr-SA/CNF sponge, after 5 cycles of recycling, the photodegradation rates of BiOBr-SA/CNF sponge to rhodamine B remained above 90.2 % (90 min), and it also has excellent photocatalytic degradation effect on methyl orange and herbicide isoproteron. This work may provide a convenient and efficient method to construct self-supporting and floating photocatalytic sponges using cellulose based materials as substrates for sewage treatment.