**Integrated Au/TiO2 Nanostructured Photoanodes for Photoelectrochemical Organics Degradation**

**Roberto Matarrese 1,\*, Michele Mascia 2, Annalisa Vacca 2, Laura Mais 2, Elisabetta M. Usai 2, Matteo Ghidelli 3,4, Luca Mascaretti 3,5, Beatrice R. Bricchi 3, Valeria Russo 3,6, Carlo S. Casari 3,6, Andrea Li Bassi 3,6, Isabella Nova <sup>1</sup> and Simonetta Palmas 2,\***


Received: 7 March 2019; Accepted: 2 April 2019; Published: 5 April 2019

**Abstract:** In this work, hierarchical Au/TiO2 nanostructures were studied as possible photoanodes for water splitting and bisphenol A (BPA) oxidation. TiO2 samples were synthetized by Pulsed Laser Deposition (PLD), while Au nanoparticles (NPs) were differently dispersed (i.e., NPs at the bottom or at the top of the TiO2, as well as integrated TiO2/Au-NPs assemblies). Voltammetric scans and electrochemical impedance spectroscopy analysis were used to correlate the morphology of samples with their electrochemical properties; the working mechanism was investigated in the dark and in the presence of a light radiation, under neutral pH conditions towards the possible oxidation of both bisphenol A (BPA) and water molecules. Different behavior of the samples was observed, which may be attributed mainly to the distributions of Au NPs and to their dimension as well. In particular, the presence of NPs at the bottom seems to be the crucial point for the working mechanism of the structure, thanks to scattering effects that likely allow to better exploit the radiation.

**Keywords:** photoelectrocatalysis; TiO2 nanostructures; Au nanoparticles; water splitting; bisphenol A oxidation
