Engineering Lattice Disorder on a Photocatalyst: Photochromic BiOBr Nanosheets Enhance Activation of Aromatic C–H Bonds via Water Oxidation

Abstract

Solar-driven photocatalytic reactions can mildly activate hydrocarbon C–H bonds to produce value-added chemicals. However, the inefficient utilization of photogenerated carriers hinders the application. Here, we report reversible photochromic BiOBr (denoted as p-BiOBr) nanosheets that were colored by trapping photogenerated holes upon visible light irradiation and bleached by water oxidation to generate hydroxyl radicals, demonstrating enhanced carrier separation and water oxidation. The photocatalytic coupling and oxidation reactions of ethylbenzene were efficiently realized by p-BiOBr in a water-based medium under ambient temperature and pressure (apparent quantum yield is 14 times that of pristine BiOBr). The p-BiOBr nanosheets feature lattice disordered defects on the surface, providing rich uncoordinated catalytic sites and inducing structural distortions and lattice strain, which further leads to an altered band structure and significantly enhanced photocatalytic performances. These hole-trapping materials open up the possibility of substantially elevating the utilization efficiency of photogenerated holes for high-efficiency photocatalytic activation of various saturated C–H bonds.

BiOX/Bi/BiOX (X = Cl, Br) Double‐Side Nanosheet Arrays: Synthesis, Structures, and Photo(electro)catalytic Applications

“…BiOX (X = Cl, Br), as a promising photocatalyst, has been widely used because of its characteristic layered structure, ideal band gap, and excellent chemical stability. [2] The catalytic performance of BiOX can further be tuned by the fabrication of 2D/3D layered structures, [3][4][5] construction of heterojunction composite, [6] crystal engineering, [3] and the use of hybrid materials. [7] The construction of a heterojunction structure, which can broaden the light absorption and provide high active sites, is an effective way to improve photocatalytic performance.…”

“…BiOX (X = Cl, Br), as a promising photocatalyst, has been widely used because of its characteristic layered structure, ideal band gap, and excellent chemical stability. [ 2 ] The catalytic performance of BiOX can further be tuned by the fabrication of 2D/3D layered structures, [ 3–5 ] construction of heterojunction composite, [ 6 ] crystal engineering, [ 3 ] and the use of hybrid materials. [ 7 ]…”

Enhanced Selective Photooxidation of Toluene to Benzaldehyde over Co3O4‐Modified BiOBr/AgBr S‐Scheme Heterojunction

“…Then, the benzyl radicals can react with •O 2 À radical to produce the peroxyl products, which can be easily decompose to benzaldehyde through a dehydration process. [1,2] Considering that the formation of benzyl alcohol requires hydroxyl radical, [63] it is reasonable that the are mainly benzaldehyde because of the water-lack reaction condition.…”

“…is of vital importance for organic synthesis and transformation among the field of manufacturing industry. [1][2][3] However, because of the strong bond dissociation energy of sp 3 C─H in toluene (85.5 kcal mol À1 ), [4] the thermal activation and oxidation of C─H process is tough and energy consuming. [5][6][7][8][9] In a typical thermal catalytic procedure, harsh conditions, including high temperature and pressure, as well as the addition of toxic and aggressive oxidation reagents, are required, thus causing poor product selectivity.…”

“…[19] Among various semiconductor photocatalysts, BiOBr draws much attention because of its unique laminar structure and suitable band configuration as well as stable physicochemical properties. [2,[20][21][22] Specifically, BiOBr possesses a unique 2D layered structure that the [Bi 2 O 2 ] 2þ sheets are sandwiched by two-layer of Br À via van der Waals interaction along vertical direction. Such a structure induces the formation of an internal electric field between layers in the direction of [001], which benefits the charge-carrier migration and separation process.…”