Photoproduction of Hydrogen from Hydrocarbons

Hashimoto et al. [82] reported the photocatalytic production of hydrogen from aliphatic and aromatic hydrocarbons using a powdered Pt/Ti02 photocatalyst suspended in deaerated water. The hydrocarbon-water-photocatalyst system was exposed to UV irradiation 

No other products were detected in the gas phase. The amount of H2 produced from 85 pmol of m-C16H34 was 4.14 mmol, which is close to the stoichiometric value. One can note that reaction 2.72 stoichiometry resembles that of steam reforming of hexadecane. The authors proposed the following mechanism, which involves the initial generation of active species holes (p+) in the valence band and electrons (e ) in the conduction band of 

The mechanism of IPT-catalyzed conversion of alkanes (RH) involves the photoinduced charge transfer in the photoactive WVI = O group in the octahedral moiety (A) leading to the formation of a reactive electron-deficient radicallike specie (B) capable of abstracting H atom from organic substrates ( denotes an excited state)  

The intermediately formed alkyl radical could be either further oxidized in presence of IPT and water molecules yielding corresponding alcohols or recombine with other radical (dimerization reaction)  

Photoreduced (C.) species undergo a number of dark redox transformations (including disproportionation 2WV — WVI + W ) leading to their original oxidized form (A) with the release of hydrogen. In a simplified form, hydrogen production can be written as follows  

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