Hyperbranched potassium lanthanum titanate perovskite photocatalysts for hydrogen generation

Abstract

Semiconductors with hierarchical nanostructured morphologies may be promising as high surface area photocatalysts for producing hydrogen from water. However, there are few scalable synthesis methods that can achieve such morphologies in metal oxide semiconductors such as titanates. Here, hydrothermal methods were used to synthesize nanostructured potassium lanthanum titanate (KLTO) perovskite without using templates or structure-directing agents. The obtained materials were octahedral particles composed of orthogonal hyperbranched nanowires, a morphology that is usually obtained using catalyst-mediated vapor phase methods. Several fundamental materials properties of KLTO were determined for the first time, including the bandgap (3.3 eV), semiconductor type (n-type), flat band potential, and conduction band maximum (−0.265 V and −0.835 V vs. NHE, respectively). The KLTO hyperbranched structures were also investigated as UV-photocatalysts for H₂ production and displayed higher activities than P25 TiO₂ and KLTO nanoparticles. The H₂ production rate for KLTO decorated with 1 wt% Pt using thermal decomposition of K₂PtCl₄ reached ca. 2.5 mmol h⁻¹ and was stable for 20 h of irradiation.