Cs₃Bi₂Br₉ Nanodots Stabilized on Defective BiOBr Nanosheets by Interfacial Chemical Bonding: Modulated Charge Transfer for Photocatalytic C(sp³)–H Bond Activation

Abstract

In the design of photocatalysts for C­(sp 3)–H selective oxidation, photogenerated holes have been regarded as critical for C­(sp 3)–H dissociation. However, poor charge-transfer efficiency restricts the localization of holes on the surface of the catalyst. Herein, a Z-scheme structure modulated by interfacial chemical bonding is constructed via the in situ growth of Cs3Bi2Br9 nanodots (CBB) on defective BiOBr nanosheets (d-BiOBr) for photocatalytic toluene selective oxidation. Benefited from the interfacial internal electric field, the Bi–Br bond becomes a direct channel to accelerate electron transfer from the conduction band of d-BiOBr to the valence band of CBB, resulting in a higher localization of charges on the surface of CBB/d-BiOBr. By in situ diffuse reflectance infrared Fourier transform spectroscopy, electron paramagnetic resonance, and density functional theory calculations, the surface localization of holes is proved to be essential for toluene adsorption and the dissociation of C­(sp 3)–H bond. The optimized CBB/d-BiOBr performs well in the selective oxidation of toluene to benzaldehyde and benzyl alcohol, giving a conversion rate of up to 72.3 μmol h–1 and a selectivity of nearly 100%. The activity of CBB/d-BiOBr is 26.6-fold and 6.8-fold that of pristine d-BiOBr and CBB, respectively.

Ce Doping Boosts the Photocatalytic Activity of Ultrathin Bi2MoO6 Nanosheets for Toluene Selective Oxidation

“…For further verifying the reaction process of photocatalytic toluene selective oxidation and the generation of ROS, the generated superoxide radicals are monitored in situ by ESR. 61,62 As shown in Figure 8b, after 10 min of irradiation, the signal peak in 5-CBMOS is significantly stronger than those in BMOS and BMO. It indicates that many more superoxide radicals (•O 2 − ) are generated over 5-CBMOS.…”

“…The results show that when the substituent group of toluene is an electron-absorbing group such as −Br and −NC, the catalytic activity of the catalyst is reduced, and when the substituent group is an electron-donating group such as −OH and −C­(CH 3 ) 3 , the catalytic activity of the reactant is enhanced. It indicates that the activation of toluene C–H can be promoted by electron-donating groups to a certain extent, while it may be inhibited by electron-absorbing groups. ,, In conclusion, 5-CBMOS is a kind of photocatalyst with good substrate applicability and excellent performance.…”

“…It indicates that the activation of toluene C−H can be promoted by electrondonating groups to a certain extent, while it may be inhibited by electron-absorbing groups. 8,27,62 In conclusion, 5-CBMOS is a kind of photocatalyst with good substrate applicability and excellent performance.…”

“…Combined with the experimental results of the reaction under vacuum conditions, it fully demonstrates that the hole and superoxide radical species are the main active species in the reaction. For further verifying the reaction process of photocatalytic toluene selective oxidation and the generation of ROS, the generated superoxide radicals are monitored in situ by ESR. , As shown in Figure b, after 10 min of irradiation, the signal peak in 5-CBMOS is significantly stronger than those in BMOS and BMO. It indicates that many more superoxide radicals (•O 2 – ) are generated over 5-CBMOS.…”

Recent developments in lead-free bismuth-based halide perovskite nanomaterials for heterogeneous photocatalysis under visible light

“…In addition, some composite materials such as Cs 3 Bi 2 Br 9 -TiO 2 or -BiOBr or -CdS or -Ti 3 C 2 T x or -C 3 N 4 have been successfully applied in C–H bond activation with improved photocatalytic performance, especially for the oxidation of toluene. 107,108,113,156,157…”