(511e) Hydrogen Generation Using Coupled ZnO/TiO2 Photocatalyst Oxides

In most cases, coupled semiconductor oxide photo-catalysts, have activities superior to those of pure photo-catalyst oxides.  A systematic study of the nature of interaction between component semiconductor oxides, mode of preparation, surface orientation and surface area, composition of the simple binary oxide systems in relation to its photo-catalytic activity in water splitting could give a clearer picture of the origin of modified photo-activity in them.  A systematic study and effectiveness of different forms of coupled titania and zinc oxide compositions for water splitting has not been studied.  The present research deals with such a systematic study on a coupled ZnO/TiO₂ system.  Ordered mesoporous coupled TiO₂/ZnO materials were synthesized using Pluronic P123 (P123) as the surfactant, titanium butoxide and ZnCl₂ precursors.

Photocatalytic hydrogen evolution was carried out in a 7 mL quartz reactor at ambient temperature.  The focused intensity and area on the quartz cuvette were 0.60 W and 2 cm², respectively.  In a typical experiment, 2.0 mg of ZnO-TiO₂ photocatalyst was dispersed in 3.5 mL of H₂O and 0.5 mL methanol or 10 mg biomass as sacrificial agents.  A 300 W xenon lamp (Oriel) equipped with a UV-filter (λ = 240 nm- 400 nm) was employed as the light source.  Prior to irradiation, the suspension of the catalyst was degassed with ultrapure nitrogen for 30 min to completely remove the dissolved oxygen and to ensure the reactor in an anaerobic condition.  From 3 mL overhead, 0.1 mL of gaseous samples were withdrawn periodically and injected into the gas chromatograph (GC), from which photocatalytic activity for hydrogen evolution was evaluated.  

XRD, UV-Vis spectra, SEM/TEM and N₂ adsorption-desorption isotherm analysis of coupled ZnO/TiO₂ composites and H₂ generation from photocatalytic water-splitting reaction will be presented.