An in situ simultaneous reduction-hydrolysis technique for fabrication of TiO2-graphene 2D sandwich-like hybrid nanosheets: Graphene-promoted selectivity of photocatalytic-driven hydrogenation and coupling of CO 2 into methane and ethane

Abstract

A novel, in situ simultaneous reduction-hydrolysis technique (SRH) is developed for fabrication of TiO2 - graphene hybrid nanosheets in a binary ethylenediamine (En)/H2O solvent. The SRH technique is based on the mechanism of the simultaneous reduction of graphene oxide (GO) into graphene by En and the formation of TiO2 nanoparticles through hydrolysis of titanium (IV) (ammonium lactato) dihydroxybis, subsequently in situ loading onto graphene through chemical bonds (Ti-O-C bond) to form 2D sandwich-like nanostructure. The dispersion of TiO2 hinders the collapse and restacking of exfoliated sheets of graphene during reduction process. In contrast with prevenient G-TiO2 nanocomposites, abundant Ti3+ is detected on the surface of TiO2 of the present hybrid, caused by reducing agent En. The Ti3+ sites on the surface can serve as sites for trapping photogenerated electrons to prevent recombination of electron-hole pairs. The high photocatalytic activity of G-TiO2 hybrid is confirmed by photocatalytic conversion of CO 2 to valuable hydrocarbons (CH4 and C2H 6) in the presence of water vapor. The synergistic effect of the surface-Ti3+ sites and graphene favors the generation of C 2H6, and the yield of the C2H6 increases with the content of incorporated graphene. The work may open a new doorway for new significant application of graphene for selectively catalytic C-C coupling reaction A novel, in situ simultaneous reduction-hydrolysis technique (SRH) is developed for fabrication of TiO2-graphene hybrid nanosheets in a binary ethylenediamine (En)/H2O solvent. The photogenerated electrons in TiO2 nanoparticles are transferred onto graphene, which minimizes charge recombination losses to improve the efficiency of photoreduction of CO2 into hydrocarbon fuel. The synergistic effect of the surface-Ti3+ abundant TiO2 and graphene favors the generation of C2H6. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.