Selective photocatalytic benzene hydroxylation to phenol using surface- modified Cu2O supported on graphene

[EN] The photocatalytic activity for benzene hydroxylation to phenol by hydrogen peroxide has been evaluated using a series of photocatalysts based on defective graphene. The series includes defective graphene containing or not Au and Cu2O nanoparticles. The latter exhibits the highest activity, but a very low phenol yield as a consequence of the occurrence of a large degree of mineralization. A considerable increase in phenol selectivity was achieved by modifying the surface of the Cu2O nanoparticles supported on defective graphene with long-chain alkanethiols. Under the optimal conditions using an octanethiol-modified Cu2O-graphene photocatalyst, a selectivity to phenol of about 64% at 30% benzene conversion was achieved. This remarkable selectivity was proposed to derive from the larger hydrophobicity of the alkanethiol-modified Cu2O-graphene photocatalyst that favors the preferential benzene adsorption versus adsorption of phenol and hydroxybenzenes. J. H. thanks the Chinese Scholarship Council for a graduate scholarship. Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, CTQ2015-69653-CO2-R1 and Grapas) and Generalitat Valenciana (Prometeo 2017-083) is gratefully acknowledged. This work was also supported by NSFC (21872031, U1705251) and 973 Program (2014CB239303) of P. R. China. He, J.; Zhang, M.; Primo Arnau, AM.; García Gómez, H.; Li, Z. (2018). Selective photocatalytic benzene hydroxylation to phenol using surface- modified Cu2O supported on graphene. Journal of Materials Chemistry A. 6(40):19782-19787. https://doi.org/10.1039/c8ta07095d Xiang, Q., Yu, J., & Jaroniec, M. (2012). Graphene-based semiconductor photocatalysts. Chem. Soc. Rev., 41(2), 782-796. doi:10.1039/c1cs15172j Zhang, N., Zhang, Y., & Xu, Y.-J. (2012). Recent progress on graphene-based photocatalysts: current status and future perspectives. Nanoscale, 4(19), 5792. doi:10.1039/c2nr31480k Nourbakhsh, A., Cantoro, M., Vosch, T., Pourtois, G., Clemente, F., van der Veen, M. H., … Sels, B. F. (2010). Bandgap opening in oxygen plasma-treated graphene. Nanotechnology, 21(43), 435203. doi:10.1088/0957-4484/21/43/435203 Putri, L. K., Ong, W.-J., Chang, W. S., & Chai, S.-P. (2015). Heteroatom doped graphene in photocatalysis: A review. Applied Surface Science, 358, 2-14. doi:10.1016/j.apsusc.2015.08.177 Wang, X., Sun, G., Routh, P., Kim, D.-H., Huang, W., & Chen, P. (2014). Heteroatom-doped graphene materials: syntheses, properties and applications. Chem