On the selectivity of butyric acid photoreforming over Au/TiO2 and Pt/TiO2 by UV and visible radiation: A combined experimental and theoretical study

Abstract Commercial TiO2 (P25) and synthesized TiO2 nanorods (TNR) decorated by either Pt or Au nanoparticles, were used in the butyric acid photoreforming (BAPR) and characterized by XRD, TEM/EDS, porosimetry, and DRS. The selectivity toward a wide range of products (H2, CO2, alkanes, alkenes, organic acids) was investigated under three different irradiation sources (UV, vis, UV + vis). Butyric acid conversion (XBA) and the selectivity to H2 (SH2), propane (SC3H8), propene (SC3H6) are suggested to be mainly affected by holes in the TiO2 valence band, electrons over the noble metal, electrons in the TiO2 conduction band, and holes over the metal, respectively. The highest XBA and SH2 were recorded with Pt/P25 under UV, whereas the largest SC3H8 and SC3H6 were observed with Au/TNR under UV + vis. First-principles calculations were performed with the aid of density functional theory, to investigate the energetic properties of metal/oxide structures and further elucidate the photocatalytic mechanism observed in the experiments.