Anion‐exchange synthesis of hollow BiOCl/Bi ₂ S ₃ hybrids with superior capability for photocatalytic reduction of hexavalent chromium under visible light irradiation

Abstract

BiOCl/Bi 2 S 3 hollow hybrids were synthesised through a mild anion-exchange method from BiOCl microspheres and thiacetamide. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption measurements, ultraviolet-visiblenear-infrared diffuse reflectance spectra, photocurrent, and electrochemical impedance spectroscopy (EIS) were employed to study the composition, structure, and properties of the as-synthesised BiOCl/Bi 2 S 3 hybrids. Compared to pure Bi 2 S 3 and BiOCl products, the as-prepared BiOCl/Bi 2 S 3 hollow hybrids exhibited superior capability for photocatalytic reduction of hexavalent chromium under vis light irradiation. The photocurrent and EIS results demonstrated that the low recombination rate of photoinduced electron-hole pairs was contributed to the enhanced photoreduction activity.

The direct Z-scheme character and roles of S vacancy in BiOCl/Bi2S3-(001) heterostructures for superior photocatalytic activity: a hybrid density functional investigation

“…In BiOCl/Bi 2 S 3 heterostructure experiments, 2,3,5,[15][16][17][18][19] the researchers are very concerned about the reduction ability of the BiOCl/Bi 2 S 3 heterostructures, such as the reduction of Cr 6+ to Cr 3+ and O 2 to O 2 À ; whereas the reduction ability of hydrogen generation from water, which is one of the significant applications of photocatalysts, 1 has been seldom discussed. For water-splitting to produce hydrogen, although BiOCl/Bi 2 S 3 -(001) and BiOCl/V S -Bi 2 S 3 -(001) heterostructures have suitable band edge positions for overall water-splitting, shown in Fig.…”

“…Indeed, constructing BiOCl/Bi 2 S 3 heterostructures in experiments has been demonstrated as a very effective strategy that not only can decrease the recombination of photo-generated carriers but can also improve the visible light absorption, further boosting the photocatalytic performance. [2][3][4][5][6][14][15][16][17][18][19] For example, Jia et al 20 reported that the synthetic BiOCl/Bi 2 S 3 heterostructure exhibits improved optical properties and an enhanced efficient a Guizhou Provincial Key Laboratory of Computational Nano-Material Science, degradation rate of Rhodamine B, compared to single BiOCl and Bi 2 S 3 . Tanveer et al 19 indicated that the BiOCl/Bi 2 S 3 heterostructure exhibits enhanced photocatalytic activity for the degradation of methyl orange due to the highly efficient separation rate of photo-generated electron-hole pairs.…”

“…Tanveer et al 19 indicated that the BiOCl/Bi 2 S 3 heterostructure exhibits enhanced photocatalytic activity for the degradation of methyl orange due to the highly efficient separation rate of photo-generated electron-hole pairs. Among these BiOCl/Bi 2 S 3 heterostructure experiments, [2][3][4][5][6][14][15][16][17][18] several experiments explicitly showed the concrete crystal coupling between BiOCl and Bi 2 S 3 . [2][3][4] Although, in other experiments, the specific crystal facets of BiOCl and Bi 2 S 3 were not reported.…”

“…[7][8][9] Among these methods, constructing a heterostructure with other semiconductors is considered the most promising and popular method for enhancing its photocatalytic efficiency. [10][11][12][13] For example, another significant Bi-based semiconductor photocatalyst Bi 2 S 3 (space group Pbnm (#62)) was adopted to build BiOCl/Bi 2 S 3 heterostructures by many experimental working groups, [2][3][4][5][6][14][15][16][17][18] in order to enhance the photocatalytic activities of both BiOCl and Bi 2 S 3 . One important reason is that Bi 2 S 3 has a narrow band gap of 1.33-1.70 eV that can strongly absorb visible light, 5,14 also has a layered structure, and complements the larger band gap of BiOCl when BiOCl and Bi 2 S 3 are coupled to form a heterostructure.…”

“…[2][3][4] Although, in other experiments, the specific crystal facets of BiOCl and Bi 2 S 3 were not reported. 5,6,15,16,18 Yet, both experimental and theoretical studies have shown that Bi 2 S 3 prefers to grow along the (001) direction, 4,21,22 and BiOCl tends to expose the (001) facet in the crystal growth process. 23,24 Therefore, in several experimental working groups, [2][3][4] the (001) facet of BiOCl with high photocatalytic activity obtained through a controllable preparation strategy was coupled with the Bi 2 S 3 (001) crystal facet to form BiOCl/Bi 2 S 3 -(001) heterostructures and these heterostructures present excellent photocatalytic activities for the tetracycline degradation, Cr 6+ reduction and photoelectrochemical performance.…”