Tailored graphenic structures directly grown on titanium oxide boost the interfacial charge transfer

Abstract

The successful application of titanium oxide-graphene hybrids in the fields of photocatalysis, photovoltaics and photodetection strongly depends on the interfacial contact between both materials. The need to provide a good coupling between the enabling conductor and the photoactive phase prompted us to directly grow conducting graphenic structures on TiO2 crystals. We here report on the direct synthesis of tailored graphenic structures by using Plasma Assisted Chemical Vapour Deposition that present a clean junction with the prototypical titanium oxide (1 1 0) surface. Chemical analysis of the interface indicates chemical bonding between both materials. Photocurrent measurements under UV light illumination manifest that the charge transfer across the interface is efficient. Moreover, the influence of the synthesis atmosphere, gas precursor (C2H2) and diluents (Ar, O2), on the interface and on the structure of the as-grown graphenic material is assessed. The inclusion of O2 promotes vertical growth of partially oxidized carbon nanodots/rods with controllable height and density. The deposition with Ar results in continuous graphenic films with low resistivity (ρ = 6.8 · 10−6 Ω·m). The synthesis protocols developed here are suitable to produce tailored carbon-semiconductor structures on a variety of practical substrates as thin films, pillars or nanoparticles.