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Production of hydrogen by water photo-splitting over commercial and synthesised Au/TiO<inf>2</inf> catalysts

Abstract:

H2 production from methanol/water photo-splitting was compared using various commercial photocatalysts (Evonik P25 (P25), Hombikat UV-100 (HB) and Kronos vlp7000 (KR)) and others synthesised with a sol-gel-hydrothermal (HT) process and a sol-gel method followed by calcination (SG400 and SG750). All photocatalysts had been surface modified with Au at different concentrations, from 0.2 to 6.0wt.%, using the photodeposition method. A complete characterisation study of the different photocatalysts was performed (BET, XRD, TEM, SEM-EDX, FTIR, UV-vis Reflectance Diffuse Spectra and aggregate size). The experiments were conducted for 3.5h using 1gL-1 of photocatalyst with methanol (25vol.%) as sacrificial agent. In addition to H2 generation, production of the main intermediates, formaldehyde and formic acid, and of CO2 was also evaluated. The commercial photocatalyst KR at 0.8wt.% Au had the highest H2 production of all the photocatalysts studied with 1542.9μmolh-1. Of the photocatalysts synthesised by our group, SG750 at Au loading of 2.0wt.% gave the highest H2 production of 723.1μmolh-1. The SG750 photocatalyst at Au loading of 2.0wt.% also had the highest H2 production yield per unit of surface area at 45.5μmolgh-1m-2. © 2013.