Investigation of the appropriate content of graphene in AgTiO2-graphene ternary nanocomposites applied as photocatalysts

AgTiO2-graphene ternary nanocomposites with varying graphene contents were fabricated by photocatalytic reduction. SEM and TEM imaging of the nanocomposites showed that TiO2 nanoparticles decorated with Ag nanoparticles covered graphene nanosheets. A higher content of graphene was shown to be favorable for dye photodegradation. The results of electrochemical analysis revealed that a higher graphene content contributed to increased conductivity and reduced interfacial impedance, which led to more efficient electron transport and thus higher photocatalytic activity. The highest efficiency in dye photodegradation and hydrogen production from water splitting was achieved when the ratio of TiO2 to graphene in the nanocomposite was 5: 1. The corresponding mass-normalized hydrogen evolution rate and quantum efficiency were 129.5 μmol g−1 h−1 and 4.8%, respectively. A mechanism for photocatalysis was proposed and discussed. This study demonstrates that the AgTiO2-graphene ternary nanocomposite could be a promising photocatalyst.