Morphology Regulation Mechanism and Enhancement of Photocatalytic Performance of BiOX (X = Cl, Br, I) via Mannitol-Assisted Synthesis

Abstract

BiOX (X=Cl, Br, I) photocatalysts with dominant (110) facets were synthesized via a mannitol-assisted solvothermal method. This is the first report on the exposed (110) facets-, size-, and defects-controlled synthesis of BiOX achieved by solvothermal synthesis with mannitol. This polyol alcohol acted simultaneously as a solvent, capping agent, and/or soft template. The mannitol concentration on the new photocatalysts morphology and surface properties was investigated in detail. At the lowest concentration tested, mannitol acted as a structure-directing agent, causing unification of nanoparticles, while at higher concentrations, it functioned as a solvent and soft template. The effect of exposed (110) facet and surface defects (Bi(3−x)+, Bi4+, Bi5+) of BiOX on the photocatalytic activity of nanomaterials under the UV–Vis irradiation were evaluated by oxidation of Rhodamine B (RhB) and 5-fluorouracil (5-FU), an anticancer drug, and by reduction of Cr(VI). Additionally, the influence of crucial factors on the formation of BiOX in the synthesis with mannitol was discussed extensively, and the mechanism of BiOX formation was proposed. These studies presented a new simple method for synthesizing BiOX without any additional surfactants or shape control agents with good photocatalytic activity. The study also provided a better understanding of the effects of solvothermal conditions on the BiOX crystal growth.

Synergy of oxygen vacancies and Bi nanoparticles on BiOBr nanosheets for enhanced photocatalytic H2O2 production

“…The formations of metal Bi and BiOBr are two competitive reactions that are going on at the same time, 42 and BiO + reduction is a dynamic reversible reaction due to the weak reducibility of mannitol. 43 At first, due to the high density and viscosity of the mannitol solution and the weak interaction with bromine ions, the formation of BiOBr nanosheets is relative slower, leading to a large amount of free BiO + ion exposition to the reductive mannitol in a long time, which is advantageous to the BiO + reduction. As the reaction time increases, the amount of free BiO + is relative decreased.…”

Oxygen Vacancy-Modified BiOCl Nanoplates via Three Minutes Mannitol-Assisted Grinding Treatment for Excellent Photocatalytic Applications

“…After the addition of different proportions of mannitol, the growth of its (001) surface was inhibited, and BiOCl nanoplates became ultrathin. This is caused by the Bi 3+ reaction with mannitol to form a homogeneous Bi[OCH 2 (CHOH) 4 OH] 2+ solution; then, the hydrogen bond interaction between the surface hydroxyl groups of the mannitol molecule and the oxygen atom in the BiOCl (001) plane takes place . However, the diffraction peak (110) at 32.6° indicates that modified BiOCl has a high (110) surface area for exposure to light.…”

Bismuth Oxyhalide-Based Materials (BiOX: X = Cl, Br, I) and Their Application in Photoelectrocatalytic Degradation of Organic Pollutants in Water: A Review

“…The ability of BiOXs to absorb light in the visible spectrum plays a key role in their photocatalytic activity ( Wilczewska et al, 2021 ). The success of BiOX-based materials in photocatalytic and photoelectrocatalytic applications is related to the hierarchy of their surface structures, which significantly improve the ability to absorb visible light with respect to BiOXs.…”