Enhanced photocatalytic performances of TiO2-graphene hybrids on nitro-aromatics reduction to amino-aromatics

Graphene sheets have been considered as acceptors and transporters of photoinduced electrons generated from illuminated photocatalysts. Herein, we utilize these electrons with the help of graphene sheets in photocatalytic selective reduction. First, graphene-modified TiO2 hybrids are prepared by electrostatic assembly and in situ photocatalytic reduction processes using P25 and graphene oxide as precursors and then the photocatalytic reduction of nitro-aromatics to the corresponding amino-aromatics with these hybrids is examined under UV light irradiation. Results indicate that the addition of graphene sheets can effectively minimize the recombination of photogenerated charge carriers derived from the irradiated TiO2 and better encourage these separated electrons to participate in the reactions, which effectively improves the reduction ability of these TiO2-graphene hybrids in the presence of oxalic acid as hole scavengers. Besides the enhanced conversion rate, higher yields of amino-aromatics are achieved when using the graphene-modified TiO2 as a photocatalyst compared with those for pure TiO2.