Photocatalytic Hydrogen Production

The photocatalytic methanol reforming reaction has been studied using many different Pd/Pt loaded TiO2 powdered catalysts, focussing on the effect of weight loading and reaction phase on the rate of hydrogen production. The palladium/platinum weight loading dependence in the gas and liquid phase showed that independent of the phase of reaction, the amount of hydrogen produced from methanol reforming irradiated by UV light decreased for increasing metal weight loading. Further studies were conducted to test the reactivity of rutile and anatase phase titania supported palladium/platinum catalysts for their ability to produce hydrogen in the methanol reforming reaction, both phases were found to be poor photocatalysts alone but upon combination both chemically in the P25 based catalysts and in physical mixtures, where Pd was present on only the rutile phase, the amount of hydrogen produced was improved. The reactivity of surface oxygen and crotonaldehyde has also been studied under ultra-high vacuum (UHV) conditions on Pd (110). Key UHV techniques employed included molecular beam sticking, X-ray photoelectron spectroscopy (XPS). Adsorbed oxygen was found to migrate into the bulk following molecular beam experiments where the period between incident beam exposure on the Pd crystal was altered over time. For the crotonaldehyde molecular beam experiments decarbonylation was observed for ambient reaction temperatures and dehydrogenation was observed at elevated temperatures. Successful palladium growth by the Volmer-Weber island growth mode were reported for the production of a model Pd/TiO2 (110) catalyst via metal vapour deposition (MVD) however surface palladium concentration was too low for molecular sticking reactions to be carried out on the surface