Photoinduced hydrogen production from an aqueous solution of ethylene glycol over ultrafine gold supported on TiO2

Abstract Photocatalytic H 2 production from aqueous solutions of ethylene glycol was studied using a catalyst consisting of gold supported on TiO 2 . The catalysts were prepared by the deposition-precipitation method, using TiO 2 powder and an aqueous solution of chloroauric acid. Transmission electron microscopy showed that Au was deposited as highly dispersed particles with mean diameters of 2 to 5 nm, depending on the method of pretreatment of the precursor. The effects of precursor calcination temperature, duration of irradiation, gold loading, concentration of ethylene glycol, initial pH and temperature on H 2 production were investigated. The gas phase products of the reaction were mainly H 2 and CO 2 . The precursor calcined in air at 673 K proved to be the most active photocatalyst. The yield of H 2 exhibited a weak maximum at a gold loading of about 2 wt.%. The rate of H 2 production was strongly dependent on the initial pH of the suspension; it increased with pH up to neutral pH and decreased thereafter. Increasing the concentration of ethylene glycol and the temperature had a positive effect on the H 2 yield. The activation energy of H 2 production, as given by an Arrhenius plot over the temperature range 284–340 K, was 15 kJ mol −1 .

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