Photocurrent Enhancements of TiO2-Based Nanocomposites with Gold Nanostructures/Reduced Graphene Oxide on Nanobranched Substrate

In this work, we studied three-dimensional (3D) highly branched TiO2 nanorod (b-NR) arrays decorated with plasmonic Au triangular nanoprisms (TNPs) and reduced graphene oxide (rGO) sheets for photoelectrochem- ical (PEC) water oxidation. The photocurrent densities of rGO/TiO2 b-NRs and Au TNPs/rGO/TiO2 b-NRs exhibited 21 and 90% enhancements, respectively, compared to bare TiO2 b-NRs at 0.5 V (vs Ag/AgCl). Incident photon-toelectron conversion efficiency measurements revealed the synergistic effects of plasmonic Au TNPs and rGO on the enhancement of photocurrent response, especially in the visible region. The electrochemical impedance spectroscopy analysis provided further evidence that the charge transport resistance between TiO2 photoanode and electrolyte was greatly reduced with the incorporation of Au TNPs and rGO. It is suggested that the plasmonic Au TNPs exhibiting localized surface plasmon resonances at 560 and 660 nm to enhance the visible light absorption, rGO with superior electron conductivity, and 3D TiO2 bNR arrays with large surface area and high carrier mobility synergistically contribute to the high PEC performance. Our results of the facile decoration of Au TNPs and rGO sheets could arouse great interest in PEC water splitting reaction and aid in the evaluation of other photoanodes.