Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO_<b>2</b>Catalyst Wrapped by High Concentrated TiO_<b>2</b>Particles

Abstract

This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO 2 photocatalyst coated with a high concentration of TiO 2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO 2 particles (&gt;4~5 mol). The synthesized core@shell-structured CuS@TiO 2 particles absorbed a long wavelength (a short band gap) above 700 nm compared to that pure TiO 2 , which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO 2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO 2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO 2 strongly withdraws the excited electrons from the valence band in TiO 2 because of the higher reduction potential than TiO 2 , resulting in a slower recombination rate between the electrons and holes and higher photoactivity.