Microwave-Assisted Synthesis of BiOCl/BiOBr Composites with Improved Visible-Light Photocatalytic Activity

Abstract

BiOCl/BiOBr composite photocatalysts with different Cl-to-Br molar ratios were synthesized by a simple microwave-assisted coprecipitation (MWAC) method.The structures, morphology and photocatalytic properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, and UV-vis absorption spectrometry. The photocatalytic activities of these BiOCl/BiOBr composites were evaluated by their ability in degradation of Rhodamine B under visible-light irradiation. Results reveal that the MWAC-synthesized 1:5BiOCl/BiOBr composite is much more active than that synthesized by the hydrothermal method. The former composite obviously maintains the high photocatalytic activity after five cycles and thus is the best one among all these photocatalysts. The visible-light photocatalytic activity enhancement of BiOCl/BiOBr composites could be attributed to their strong absorption in the visible region and the low recombination rate of electron-hole pairs. Among different scavengers, the main active species during the photocatalytic process are h + and •O 2− .The possible photocatalytic mechanism was proposed based on the experimental results.

Preparation of high‐activity AgBr/Ag3PO4 photocatalyst based on hexadecyltrimethylammonium bromide and mechanism of photocatalytic enhancement

“…Considering that benzoquinone will react with MO, which will affect the determination of absorbance, we used rhodamine B (RhB) instead of MO as the dye. In this study, the scavengers triethanolamine (TEOA), benzoquinone (BQ) and isopropyl alcohol (IPA) were used to scavenge h + , • O 2− and • OH, respectively . As shown in Figure , after adding IPA, the degradation efficiency of RhB was not significantly reduced, indicating that • OH plays a comparatively minor role for RhB degradation.…”

“…• O 2− and • OH, respectively. [28] As shown in Figure 8, after adding IPA, the degradation efficiency of RhB was not significantly reduced, indicating that • OH plays a comparatively minor role for RhB degradation. In contrast, the degradation efficiency of RhB was greatly reduced after the addition of BQ and TEOA.…”

Room‐Temperature Synthesis and Enhanced Photocatalytic Performance of BiOCl Microsphere

“…The corresponding bandgaps are obtained from the Kubelka‐Munk function, as depicted in Figure b. The bandgap energies are determined via the following equation: [hνF(R)] 1/2 = A(hν‐Eg) where hν is photon energy, F(R) serves as absorption coefficient, E g is band gap energy, and A is proportional constant, the inset demonstrates the Tauc plot of [hνF(R)] 1/2 versus hν. The bandgap energy of the samples was estimated to be approximately 3.17 (S1), 3.42 (S2), 3.41 (S3), 3.39 (S4) and 3.37 eV (S5).…”

A Mechanism Investigation of how the Alloying Effect Improves the Photocatalytic Nitrate Reduction Activity of Bismuth Oxyhalide Nanosheets

“…Bismuth‐based ternary oxide photocatalysts, bismuth oxyhalides (BiOXs, X=Cl, Br, I), are the typical visible light photocatalyst and have excellent catalytic activity than other materials . Recent studies show that alloying another halogen into bismuth oxyhalides to form the alloyed bismuth oxyhalides (BiOCl n Br 1‐n , BiOCl n I 1‐n , and BiOBr n I 1‐n ) will lead to it possesses much more active than their monohalide counterparts . Although the excellent photocatalytic activity of alloyed BiOXs has been confirmed, it is still elusive for the mechanism of the alloying‐dependent photocatalytic performance.…”

“…[22] Recent studies show that alloying another halogen into bismuth oxyhalides to form the alloyed bismuth oxyhalides (BiOCl n Br 1-n , BiOCl n I 1-n , and BiOBr n I 1-n ) will lead to it possesses much more active than their monohalide counterparts. [23][24][25][26] Although the excellent photocatalytic activity of alloyed BiOXs has been confirmed, it is still elusive for the mechanism of the alloying-dependent photocatalytic performance. More importantly, no previous investigation has been conducted on the photocatalytic denitrification ability of alloyed BiOXs, which is very critical for assessing whether the alloyed structure is a new means of constructing high efficiency NO 3 À removal catalysts.…”