A newly designed a Tio 2-loaded spherical ZnS nano/micro-composites for high hydrogen production from methanol/water solution photo-splitting

Abstract

A new system using TiO 2 (nano-sized, band-gap 3.14 eV)-impregnated spherical ZnS (micro-sized, band-gap 2.73 eV) nano/micro-composites (Ti 0.001, 0.005, 0.01, and 0.05 mol %/ZnS) was developed to enhance the production of hydrogen from methanol/water splitting. The ZnS particles in a spherical morphology with a diameter of about 2-4 mm which can absorb around 455 nm were prepared by hydrothermal method. This material was used as a photocatalyst with loading by nano-sized TiO 2 (20-30 nm) for hydrogen production. The evolution of H2 from methanol/water (1:1) photo splitting over the TiO 2/ZnS composite in the liquid system was enhanced, compared with that over pure TiO 2 and ZnS. In particular, 1.2 mmol of H2 gas was produced after 12 h when 0.005 mol % TiO 2/ZnS nano/micro-composite was used. On the basis of cyclic voltammeter (CV) and UV-visible spectrums results, the high photoactivity was attributed to the larger band gap and the lower LUMO in the TiO 2/ZnS composite, due to the decreased recombination between the excited electrons and holes.