A Newly Designed a TiO2-Loaded Spherical ZnS Nano/Micro-Composites for High Hydrogen Production from Methanol/Water Solution Photo-Splitting

摘要

A new system using TiO2 (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 TiO2 (20-30 nm) for hydrogen production. The evolution of H2 from methanol/water (1:1) photo splitting over the TiCVZnS composite in the liquid system was enhanced, compared with that over pure TiO2 and ZnS. In particular, 1.2 mmol of H2 gas was produced after 12 h when 0.005 mol % TiCVZnS 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 TiCVZnS composite, due to the decreased recombination between the excited electrons and holes.