Comparative study of alcohols as sacrificial agents in H2 production by heterogeneous photocatalysis using Pt/TiO2 catalysts

Operational Conditions Affecting Hydrogen Production by the Photoreforming of Organic Compounds using Titania Nanoparticles with Gold

“…We could assume that the increase in the available surface of catalyst used in this experiment was not enough to equate to the increase in the availability of reactant, and the link between the available area of catalyst and the amount of alcohol molecules requires a deeper analysis. Smaller effects were observed with the change of electron donor (B), which increased productivity by 27 % (from 40.6 to 51.5 μmol mol −1 h −1 ) when ethanol replaced methanol, and doubling the concentration of NPs (E) from 0.05 to 0.1 g L −1 increased the productivity just by 14 % (from 43.1 to 49.0 μmol mol −1 h −1 ), which differs from the results of recent studies in which methanol and glycerol show a bigger influence on hydrogen production rates.…”

“…Moderate and similar average effects were observed with the change of type of electron donor (B) and its concentration (D), which increase the average response by 27 % (from 45 to 57 μmol) when methanol was replaced with ethanol and by 20 % (from 46 to 57 μmol) when its concentration increased from 1.2 to 2.2 m . This increase in alcohol concentration agrees with results published previously, in which hydrogen production was dependent on the alcohol concentration for diluted solutions up to 6–7 m and if the direct oxidation of alcohol molecules by photogenerated holes occurs at the TiO 2 surface with concentrations above 0.12 m (0.47 vol %) . Its influence is related to its sequential process and the lifetimes of the photogenerated electron–hole pairs.…”

“…The concentration of the catalyst (E) and the concentration of electron donor (D) become relevant for their respective productivities and are of a similar magnitude to the intensity of light. Among the different types of alcohol (B), ethanol showed slightly better average productivities than methanol, which disagrees with some sources, and its effect is comparatively smaller and less clear than that of other single factors.…”

“…hydrogen productiona re the presence,t ype,p article size, and loading amount of cocatalysts, [41,63,67,84,86,101,120,136] and the presence,t ype,a nd concentration of sacrificial agents. [51,101,104,107,108,123,[137][138][139][140] Less studied but equally relevant for large-scale applications are the effects of light intensity [43] and photocatalyst concentration [128] because of the possible screening effect on the bulk of the reaction media. Most researchers vary one or two factors independently to define the best combinations of factors; as ar esult, interaction effects are usually not involved in these studies.…”

Hybrid systems based on metal oxide and nanocarbons: electronic properties and applications for photocatalysis

“…Its oxidation occurs over that of water molecules and consequently, this facilitates the reduction of water to hydrogen molecules. [López et al 2015] In addition to sacrificial agent, co-catalyst is also commonly used, typically noble metals such as Pt. These metals present a high work function and thus act as electron sinks that favour electron/hole pair separation.…”