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A light sensitive wide band gap radial heterojunction between TiO2 and nSiNWs sensitized by gold nanoparticles is reported. The surface plasmon of AuNPs influences the optical and photocurrent properties of the heterojunction considerably. Improvement in the band gap emission of TiO2 has been found at the expense of defect radiation. Excitation of AuNPs deposited on nSiNWs/TiO2 by light irradiation shows a wavelength-dependent photocurrent due to the increased photoactivity of the heterojunction.

The visible-light response of Au nanoparticles (AuNPs) assembled on rGO through different molecular bridges was investigated by transient photocurrent generation. We prepared rGO with two self-assembled monolayers (SAMs), one linear and the other with aromatic triazoles through a click cycloaddition reaction. A fivefold photocurrent enhancement was observed for triazole linkers over the aminopropyltrimethoxysilane (APTMS) linker. Cyclic voltammetry (CV) and impedance measurements also suggest fast electron transfer on account of the low resistance offered by the click-modified rGO surface whereby introduction of triazoles offers the efficient bridge between the donor AuNPs and acceptor rGO.