Production of hydrogen by water photo-splitting over commercial and synthesised Au/TiO2 catalysts

Abstract H 2 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 6.0 wt.%, 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 3.5 h using 1 g L −1 of photocatalyst with methanol (25 vol.%) as sacrificial agent. In addition to H 2 generation, production of the main intermediates, formaldehyde and formic acid, and of CO 2 was also evaluated. The commercial photocatalyst KR at 0.8 wt.% Au had the highest H 2 production of all the photocatalysts studied with 1542.9 μmol h −1 . Of the photocatalysts synthesised by our group, SG750 at Au loading of 2.0 wt.% gave the highest H 2 production of 723.1 μmol h −1 . The SG750 photocatalyst at Au loading of 2.0 wt.% also had the highest H 2 production yield per unit of surface area at 45.5 μmol g h −1  m −2 .