A C3N4 surface passivated highly photoactive Au-TiO2 tubular nanostructure for the efficient H2 production from water under sunlight irradiation

Abstract

In context to the recent advances in the development of sunlight active nanocomposites for the renewable H2 production from water, a C3N4 passivated Au-TiO2 tubular nanocomposite (CTA) has been prepared by a facile one pot hydrothermal method. Structural and morphological studies revealed the elongated anatase TiO2 nanotubes (200–250nm long, d=12nm) embedded in a thin layer of graphitic C3N4 (1–3nm) and dispersed Au (7–12nm) nanoparticles. The bulk C3N4 turned into monolayer due to the self exfoliation process confirmed by Raman (G band=1545cm−1). The potential voltage (I–V) characteristics revealed the non ohmic properties of the heterojunction with a good current response (1.385×10−4A). The nanocomposite showed efficient photocatalytic activity with the production of ∼88μmolh−1 (calculated=2933μmolh−1g−1) of H2 gas under direct sunlight irradiation using methanol as hole scavenger. The C3N4 is activated under sunlight and simultaneously sensitized by Au due to its plasmonic effect. The band potential of C3N4 (-1.21eV vs NHE for ECB) is more negative than TiO2 (ECB=−0.29Vs NHE) enabling photo induced electrons to easily pass the interface into the ECB of TiO2 which promotes the charge carrier separation and enhance the photocatalytic activity for H2 production.