Photocatalytic oxidation of hydrocarbons to value-added oxygen-containing compounds is a green and sustainable method. However, the efficient activation of C(sp3)–H bonds under mild conditions remains a significant challenge. In this study, we prepared BiOBr/Bi2MoO6 Z-scheme heterostructure for photocatalytic selective oxidation of toluene to benzaldehyde utilizing acetic acid as solvent. A small amount of water as an additive established an acidic environment to facilitate the formation of highly reactive hydroxyl radicals (·OH) through the O2 →·O2− → H2O2 →·OH process. The ·OH together with photogenerated holes acted as reactive species dissociate C(sp3)–H bonds, which is regarded as the rate-determining step for this reaction, boosting photocatalytic activity. Compared to the reaction system without water, the conversion of toluene increased from 23.6% to 39.0%, reaching a toluene conversion rate of 6110 μmol·g–1·h–1. Additionally, there is a slight improvement in the selectivity of benzaldehyde.
Labinger, J. A.; Bercaw, J. E. Understanding and exploiting C–H bond activation. Nature 2002, 417, 507–514.
Kesavan, L.; Tiruvalam, R.; Ab Rahim, M. H.; Bin Saiman, M. I.; Enache, D. I.; Jenkins, R. L.; Dimitratos, N.; Lopez-Sanchez, J. A.; Taylor, S. H.; Knight, D. W. et al. Solvent-free oxidation of primary carbon-hydrogen bonds in toluene using Au-Pd alloy nanoparticles. Science 2011, 331, 195–199.
Rogge, T.; Kaplaneris, N.; Chatani, N.; Kim, J.; Chang, S.; Punji, B.; Schafer, L. L.; Musaev, D. G.; Wencel-Delord, J.; Roberts, C. A. et al. C–H activation. Nat. Rev. Methods Primers 2021, 1, 43.
Yang, Y. L.; Chen, Z. Y.; Huang, H. L.; Liu, Y. X.; Zou, J. H.; Shen, S. Q.; Yan, J. W.; Zhang, J. S.; Zhuang, Z. Y.; Luo, Z. Z. et al. Synergistic surface activation during photocatalysis on perovskite derivative sites in heterojunction. Appl. Catal. B: Environ. 2023, 323, 122146.
Zhou, B.; Fan, K. Z.; Chong, Y. A.; Xu, S.; Wei, J. W.; Wei, J. K.; Sergeev, A. A.; Wong, K. S.; Li, T.; Chen, G. X. et al. Modulating adsorption-redox sites and charge separation of Cs3Bi2Br9– x @AgBr core–shell heterostructure for selective toluene photooxidation. ACS Energy Lett. 2024, 9, 1743–1752.
Xiong, L. Q.; Tang, J. W. Strategies and challenges on selectivity of photocatalytic oxidation of organic substances. Adv. Energy Mater. 2021, 11, 2003216.
Xu, X.; Wang, J.; Chen, T.; Yang, N.; Wang, S. Y.; Ding, X.; Chen, H. Deep insight into ROS mediated direct and hydroxylated dichlorination process for efficient photocatalytic sodium pentachlorophenate mineralization. Appl. Catal. B: Environ. 2021, 296, 120352.
Bai, Z. J.; Tan, X. P.; Chen, L.; Hu, B.; Tan, Y. X.; Mao, Y.; Shen, S.; Guo, J. K.; Au, C. T.; Liang, Z. W. et al. Efficient photocatalytic toluene selective oxidation over Cs3Bi1.8Sb0.2Br9 nanosheets: Enhanced charge carriers generation and C–H bond dissociation. Chem. Eng. Sci. 2022, 247, 116983.
Tan, Y. X.; Chai, Z. M.; Wang, B. H.; Tian, S.; Deng, X. X.; Bai, Z. J.; Chen, L.; Shen, S.; Guo, J. K.; Cai, M. Q. et al. Boosted photocatalytic oxidation of toluene into benzaldehyde on CdIn2S4-CdS: Synergetic effect of compact heterojunction and S-vacancy. ACS Catal. 2021, 11, 2492–2503.
Li, Z. Z.; Meng, X. C. New insight into reactive oxidation species (ROS) for bismuth-based photocatalysis in phenol removal. J. Hazard. Mater. 2020, 399, 122939.
Ma, H. Y.; Zhao, L. X.; Guo, L. H.; Zhang, H.; Chen, F. J.; Yu, W. C. Roles of reactive oxygen species (ROS) in the photocatalytic degradation of pentachlorophenol and its main toxic intermediates by TiO2/UV. J. Hazard. Mater. 2019, 369, 719–726.
Nosaka, Y.; Nosaka, A. Y. Generation and detection of reactive oxygen species in photocatalysis. Chem. Rev. 2017, 117, 11302–11336.
Xu, C. Y.; Pan, Y. T.; Wan, G.; Liu, H.; Wang, L.; Zhou, H.; Yu, S. H.; Jiang, H. L. Turning on visible-light photocatalytic C–H oxidation over metal-organic frameworks by introducing metal-to-cluster charge transfer. J. Am. Chem. Soc. 2019, 141, 19110–19117.
Cao, X.; Huang, A. J.; Liang, C.; Chen, H. C.; Han, T.; Lin, R.; Peng, Q.; Zhuang, Z. W.; Shen, R. A.; Chen, H. M. et al. Engineering lattice disorder on a photocatalyst: Photochromic BiOBr nanosheets enhance activation of aromatic C–H Bonds via water oxidation. J. Am. Chem. Soc. 2022, 144, 3386–3397.
Wang, C. Y.; Zhang, X.; Zhang, Y. J.; Chen, J. J.; Huang, G. X.; Jiang, J.; Wang, W. K.; Yu, H. Q. Direct generation of hydroxyl radicals over bismuth oxybromide nanobelts with tuned band structure for photocatalytic pollutant degradation under visible light irradiation. Appl. Catal. B: Environ. 2018, 237, 464–472.
Wang, Y. X.; Li, X.; Liu, S. N.; Liu, Y.; Kong, T.; Zhang, H. Y.; Duan, X. G.; Chen, C. M.; Wang, S. B. Roles of catalyst structure and gas surface reaction in the generation of hydroxyl radicals for photocatalytic oxidation. ACS Catal. 2022, 12, 2770–2780.
Devi, M.; Chakraborty, D.; Barbhuiya, M. H.; Das, B.; Nath, S.; Dhar, S. S. Phase engineering in graphitic carbon nitride with imidazolium sulfonic acid chloride ionic liquid functionalization for photocatalytic side-chain oxidation of toluene. Appl. Catal. A: Gen. 2022, 633, 118515.
Lu, B.; Cai, N.; Sun, J.; Wang, X.; Li, X.; Zhao, J. X.; Cai, Q. H. Solvent-free oxidation of toluene in an ionic liquid with H2O2 as oxidant. Chem. Eng. J. 2013, 225, 266–270.
Zhang, Q. H.; An, B.; Lei, Y.; Gao, Z. X.; Zhang, H. N.; Xue, S.; Jin, X.; Xu, W. G.; Wu, Z. H.; Wu, M. B. et al. Cl2·– mediates direct and selective conversion of inert C(sp3)–H bonds into aldehydes/ketones. Angew. Chem., Int. Ed. 2023, 62, e202304699.
Chen, X.; Sheng, X.; Zhou, H.; Liu, Z. P.; Xu, M. M.; Feng, X. J. Hydrophobicity promoted efficient hydroxyl radical generation in visible-light-driven photocatalytic oxidation. Small 2024, 20, e2310128.
Kondo, Y.; Honda, K.; Kuwahara, Y.; Mori, K.; Kobayashi, H.; Yamashita, H. Boosting photocatalytic hydrogen peroxide production from oxygen and water using a hafnium-based metal-organic framework with missing-linker defects and nickel single atoms. ACS Catal. 2022, 12, 14825–14835.
Xia, H.; Liu, Z. L.; Xu, Y. Y.; Zuo, J. L.; Qin, Z. Z. Highly efficient V–Mo–Fe–O catalysts for selective oxidation of toluene to benzaldehyde. Catal. Commun. 2016, 86, 72–76.
Wu, X. L.; Tan, H. L.; Zhang, C. H.; Teng, Z. Y.; Liu, Z. L.; Hau Ng, Y.; Zhang, Q. T.; Su, C. L. Recent advances in two-dimensional ultrathin Bi-based photocatalysts. Prog. Mater. Sci. 2023, 133, 101047.
Ma, H.; He, Y.; Chen, P.; Wang, H.; Sun, Y. J.; Li, J. Y.; Dong, F.; Xie, G. X.; Sheng, J. P. Ultrathin two-dimensional Bi-based photocatalysts: Synthetic strategies, surface defects, and reaction mechanisms. Chem. Eng. J. 2021, 417, 129305.
Sun, Y.; Ahmadi, Y.; Kim, K. H.; Lee, J. The use of bismuth-based photocatalysts for the production of ammonia through photocatalytic nitrogen fixation. Renew. Sustain. Energy Rev. 2022, 170, 112967.
Yu, H. B.; Jiang, L. B.; Wang, H.; Huang, B. B.; Yuan, X. Z.; Huang, J. H.; Zhang, J.; Zeng, G. M. Modulation of Bi2MoO6-based materials for photocatalytic water splitting and environmental application: A critical review. Small 2019, 15, 1901008.
Zhao, Q. Y.; Hou, X. L.; Liu, X. L.; Chong, M. B.; Cheng, D. G.; Chen, F. Q.; Zhan, X. L. Facet-dependent oxygen mobility and reaction pathways for oxidative dehydrogenation of 1-butene over Bi2MoO6. ACS Catal. 2024, 14, 3543–3555.
Chen, H. J.; Xu, R. H.; Chen, D.; Lu, T. L.; Li, H. J.; Wang, M. Subsurface Mo vacancy in bismuth molybdate promotes photocatalytic oxidation of lactate to pyruvate. ACS Catal. 2024, 14, 1977–1986.
Ding, F.; Chen, P.; Liu, F.; Chen, L.; Guo, J. K.; Shen, S.; Zhang, Q.; Meng, L. H.; Au, C. T.; Yin, S. F. Bi2MoO6/g-C3N4 of 0D/2D heterostructure as efficient photocatalyst for selective oxidation of aromatic alkanes. Appl. Surf. Sci. 2019, 490, 102–108.
Cai, K.; Lv, S. Y.; Song, L. N.; Chen, L.; He, J.; Chen, P.; Au, C. T.; Yin, S. F. Facile preparation of ultrathin Bi2MoO6 nanosheets for photocatalytic oxidation of toluene to benzaldehyde under visible light irradiation. J. Solid State Chem. 2019, 269, 145–150.
Zhang, K. F.; Chen, H. X.; Liu, Y. X.; Deng, J. G.; Jing, L.; Rastegarpanah, A.; Pei, W. B.; Han, Z.; Dai, H. X. Two-dimensional Bi2W x Mo1- x O6 solid solution nanosheets for enhanced photocatalytic toluene oxidation to benzaldehyde. Appl. Catal. B: Environ. 2022, 315, 121545.
Hao, Y. C.; Dong, X. L.; Wang, X. Y.; Zhai, S. R.; Ma, H. C.; Zhang, X. F. Controllable electrostatic self-assembly of sub-3 nm graphene quantum dots incorporated into mesoporous Bi2MoO6 frameworks: Efficient physical and chemical simultaneous co-catalysis for photocatalytic oxidation. J. Mater. Chem. A. 2016, 4, 8298–8307.
Chen, C.; Qiu, G. H.; Wang, T.; Zheng, Z. Q.; Huang, M. T.; Li, B. X. Modulating oxygen vacancies on bismuth-molybdate hierarchical hollow microspheres for photocatalytic selective alcohol oxidation with hydrogen peroxide production. J. Colloid Interface Sci. 2021, 592, 1–12.
Kresse, G.; Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 1996, 6, 15–50.
Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 1999, 59, 1758–1775.
Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 1996, 77, 3865–3868.
Ma, T. X.; Yang, C. M.; Guo, L.; Soomro, R. A.; Wang, D. J.; Xu, B.; Fu, F. Refining electronic properties of Bi2MoO6 by In-doping for boosting overall nitrogen fixation via relay catalysis. Appl. Catal. B: Environ. 2023, 330, 122643.
Liu, Z.; Tian, J.; Yu, C. L.; Fan, Q. Z.; Liu, X. Q. Solvothermal fabrication of Bi2MoO6 nanocrystals with tunable oxygen vacancies and excellent photocatalytic oxidation performance in quinoline production and antibiotics degradation. Chin. J. Catal. 2022, 43, 472–484.
Jing, K. Q.; Xiong, J. H.; Qin, N.; Song, Y. J.; Li, L. Y.; Yu, Y.; Liang, S. J.; Wu, L. Development and photocatalytic mechanism of monolayer Bi2MoO6 nanosheets for the selective oxidation of benzylic alcohols. Chem. Commun. 2017, 53, 8604–8607.
Zheng, Y.; Zhou, T. F.; Zhao, X. D.; Pang, W. K.; Gao, H.; Li, S. A.; Zhou, Z.; Liu, H. K.; Guo, Z. P. Atomic interface engineering and electric-field effect in ultrathin Bi2MoO6 nanosheets for superior lithium ion storage. Adv. Mater. 2017, 29, 1700396.
Feng, R. Z.; Guo, M. N.; Yang, Z. Q.; Qiu, J. Q.; Wang, Z. Q.; Zhao, Y. L. 0D/2D Bi2MoO6 quantum dots/rGO heterojunction boosting full solar spectrum-driven photothermal catalytic CO2 reduction to solar fuels. Carbon 2024, 224, 119079.
Tian, S.; Ding, Y. F.; Cai, M. Q.; Chen, L.; Au, C. T.; Yin, S. F. Enhanced photocatalytic activity of the direct Z-scheme black phosphorus/BiOX (X = Cl, Br, I) heterostructures. Phys. Chem. Chem. Phys. 2021, 23, 17894–17903.
Zhang, J. R.; Deng, X. Z.; Gao, B.; Chen, L.; Au, C. T.; Li, K. L.; Yin, S. F.; Cai, M. Q. Theoretical study on the intrinsic properties of In2Se3/MoS2 as a photocatalyst driven by near-infrared, visible and ultraviolet light. Catal. Sci. Technol. 2019, 9, 4659–4667.
Yang, X. M.; Wang, X. N.; Liang, C. H.; Su, W. G.; Wang, C.; Feng, Z. C.; Li, C.; Qiu, J. S. Aerobic oxidation of alcohols over Au/TiO2: An insight on the promotion effect of water on the catalytic activity of Au/TiO2. Catal. Commun. 2008, 9, 2278–2281.
Wei, Q. B.; Yu, C.; Song, X. D.; Zhong, Y. P.; Ni, L.; Ren, Y. W.; Guo, W.; Yu, J. H.; Qiu, J. S. Recognition of water-induced effects toward enhanced interaction between catalyst and reactant in alcohol oxidation. J. Am. Chem. Soc. 2021, 143, 6071–6078.
Bai, Z. J.; Mao, Y.; Wang, B. H.; Chen, L.; Tian, S.; Hu, B.; Li, Y. J.; Au, C. T.; Yin, S. F. Tuning photocatalytic performance of Cs3Bi2Br9 perovskite by g-C3N4 for C(sp3)–H bond activation. Nano Res. 2023, 16, 6104–6112.
Chai, Z. M.; Wang, B. H.; Tan, Y. X.; Bai, Z. J.; Pan, J. B.; Chen, L.; Shen, S.; Guo, J. K.; Xie, T. L.; Au, C. T. et al. Enhanced photocatalytic activity for selective oxidation of toluene over cubic-hexagonal CdS phase junctions. Ind. Eng. Chem. Res. 2021, 60, 11106–11116.
Deng, X. X.; Tian, S.; Chai, Z. M.; Bai, Z. J.; Tan, Y. X.; Chen, L.; Guo, J. K.; Shen, S.; Cai, M. Q.; Au, C. T. et al. Boosted activity for toluene selective photooxidation over Fe-doped Bi2WO6. Ind. Eng. Chem. Res. 2020, 59, 13528–13538.
Jiang, Y.; Jiang, Y. S.; Cheng, S. Y.; Xi, Y. Y.; Sun, X.; Xu, Y. C.; Yang, Z. D. Modulate synthesis of CeMn solid solution using various alcohols for toluene catalytic oxidation: Synergistic effect of Ce–Mn and reaction mechanism. J. Hazard. Mater. 2024, 476, 135051.
Mi, R. L.; Li, D.; Hu, Z.; Yang, R. T. Morphology effects of CeO2 nanomaterials on the catalytic combustion of toluene: A combined kinetics and diffuse reflectance infrared fourier transform spectroscopy study. ACS Catal. 2021, 11, 7876–7889.
Xue, Z.; Yang, J. R.; Ma, L. N.; Li, H. C.; Luo, L.; Ji, K. Y.; Li, Z. H.; Kong, X. G.; Shao, M. F.; Zheng, L. R. et al. Efficient benzylic C–H bond activation over single-atom yttrium supported on TiO2 via facilitated molecular oxygen and surface lattice oxygen activation. ACS Catal. 2024, 14, 249–261.
Shi, Y. Z.; Li, P.; Chen, H. L.; Wang, Z. W.; Song, Y. J.; Tang, Y.; Lin, S.; Yu, Z. Y.; Wu, L.; Yu, J. C. et al. Photocatalytic toluene oxidation with nickel-mediated cascaded active units over Ni/Bi2WO6 monolayers. Nat. Commun. 2024, 15, 4641.
Li, S. Z.; Huber, N.; Huang, W.; Wei, W. X.; Landfester, K.; Ferguson, C. T. J.; Zhao, Y.; Zhang, K. A. I. Triazine frameworks for the photocatalytic selective oxidation of toluene. Angew. Chem., Int. Ed. 2024, 63, e202400101.
Zhang, Q. L.; Yang, S. Y.; Zhang, H. X.; He, T. Y.; Liu, W. M.; Sun, X. M.; Li, G. B.; Yu, Y. B.; Peng, H. G. Unveiling the confinement and interface effect on low temperature degradation of toluene over mesoporous zeolite encapsulated Pt-CeO2 catalyst. Chem. Eng. J. 2024, 485, 150004.
Li, Y. F.; Chen, T. Y.; Zhao, S. Q.; Wu, P.; Chong, Y. N.; Li, A. Q.; Zhao, Y.; Chen, G. X.; Jin, X. J.; Qiu, Y. C. et al. Engineering cobalt oxide with coexisting cobalt defects and oxygen vacancies for enhanced catalytic oxidation of toluene. ACS Catal. 2022, 12, 4906–4917.
Zhao, J. G.; Wang, P. F.; Wang, J.; Liu, C. L.; Wang, J. L.; Shi, L.; Xu, G. W.; Abudula, A.; Guan, G. Q. Biostarch-assisted synthesis of microscopic heterogeneous manganese-cobalt oxides for efficient catalytic combustion of toluene. Chem. Eng. J. 2023, 464, 142739.
Li, B.; Xiong, H.; Dai, W. L.; Huang, Z. L.; Zhong, X. L.; Zhang, J.; Zhou, L.; Wu, K. S.; Zou, J. P.; Luo, X. B. Enabling the activation of lattice oxygen and high distribution of Co3+ on LaCoO3 surface through fluorine incorporation to promote toluene combustion. Appl. Catal. B: Environ. Energy. 2024, 347, 123828.
Chong, Y. N.; Chen, T. Y.; Li, Y. F.; Lin, J. J.; Huang, W. H.; Chen, C. L.; Jin, X. J.; Fu, M. L.; Zhao, Y.; Chen, G. X. et al. Quenching-induced defect-rich platinum/metal oxide catalysts promote catalytic oxidation. Environ. Sci. Technol. 2023, 57, 5831–5840.