Photocatalytic dehydrogenation of organic hydrogen carrier on Pd-TiO2(110) surfaces

Abstract

Hydrogen can be stored in a liquid organic hydrogen carrier (LOHC) via the formation of chemical bonds with carbon. Most recently studied LOHC molecules store hydrogen through the transformation between cyclohexane and benzene. However, because the C–H bonds of cyclohexane are difficult to break, catalysts and high temperatures are usually required to achieve this transformation. In this study, we investigated the photocatalytic dehydrogenation of cis-1,4-diaminocyclohexane on the surface of TiO2(110) decorated with Pd nanoparticles by low-temperature scanning tunnelling microscopy and X-ray photoelectron spectroscopy. The photocatalytic dissociation of the C–H bond was observed on Pd-decorated TiO2 but not on the bare TiO2 surface under 365 nm UV irradiation. We showed that the dehydrogenation reaction is induced by hot electrons produced by the dielectric response of TiO2(110) toward plasmonic metal nanoparticles. The photocatalytic dehydrogenation is performed under extremely low temperature and pressure compared to conventional dehydrogenation processes of LOHC molecules, which suggests a prospective pathway of the H2-release process for the LOHCs.