Hydrogen production from water photosplitting using Cu/TiO2 nanoparticles: Effect of hydrolysis rate and reaction medium

A series of 10 mol% Cu/TiO2 photocatalysts were prepared by varying H2O:alkoxide molar ratios (8, 16, 32, and 64) using sol-gel associated hydrothermal method. The influence of hydrolysis rate was investigated on the physicochemical properties and photocatalytic hydrogen production by water photosplitting in an aqueous NaOH-glycerol solution. The photocatalyst characterizations were performed using thermogravimetric analysis (TGA), temperature-programmed reduction (TPR), x-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). It was found that photocatalyst with the H2O:alkoxide molar ratio of 32 produce the highest cumulative hydrogen production among all synthesized photocatalysts. Its produced hydrogen reached up to 10571 mu mol in 300 min of reaction in the aqueous NaOH-glycerol solution compared with aqueous NaOH and glycerol solutions separately. The highest photocatalytic performance can be attributed to good crystallinity, wide range visible absorption, lower bandgap energy and coexistence of Cu2O and CuO together. Furthermore, the synergetic effect of glycerol and hydroxyl groups in reaction medium enhanced the photooxidation of glycerol, reduced the deactivation of the photocatalysts and the backward reaction of O-2 and H-2 resulting in higher hydrogen production. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.