Formic Acid Photoreforming for Hydrogen Production on Shape-Controlled Anatase TiO₂ Nanoparticles: Assessment of the Role of Fluorides, {101}/{001} Surfaces Ratio, and Platinization

Abstract

Hydrogen production via formate photoreforming on TiO2 is characterized by marked dependence on the ratio between {101} and {001} surfaces for anatase nanoparticles. We observed higher rates of hydrogen evolution with the increase of the {101} facets presence, owing to their reductive nature. This helps the Pt photodeposition in the early stages of irradiation and, then, the hydrogen ion reduction reaction. The selective photodeposition of 2 nm Pt nanoparticles on {101} facets was confirmed by transmission electron microscopy (TEM) micrographs. The results are confirmed also by experiments carried out without the use of Pt as cocatalyst and by photoelectrochemical measurements. The work also explains the marginal effect of the fluorination on the H2 evolution.