On July 19, 2013, Prof. Xueming Yang of Dalian Institute of Chemical Physics of the Chinese Academy of Sciences and his colleagues reported and published their newest progress of Molecular Hydrogen Formation from Photocatalysis of Methanol on TiO2(110) on Journal of American Chemical Society. (J. Am. Chem. Soc., 2013, 135 (28), 10206–10209)

It is well established that adding methanol to water could significantly enhance H2 production by TiO2. Prof. Yang’s group has found that methanol can be photocatalytically dissociated on TiO2 (110) at 400 nm via a stepwise mechanism. However, how molecular hydrogen can be formed from the photocatalyzed methanol/ TiO2 (110) surface is still not clear. Prof Yang’s investigation provides strong evidence that molecular hydrogen can be produced via a thermal recombination reaction of hydrogen atoms on BBO rows, produced by methanol photocatalysis on rutile TiO2(110) with 400 nm irradiation, elucidating a possible and universal mechanism for H2 production with TiO2-based catalysts. From our experimental results, it clearly shows that water formation from hydroxyl pairs on BBO rows has a lower barrier than molecular hydrogen formation. From the results of their work, they concluded that lowering the barrier for hydrogen atom recombination is a key point to enhancing hydrogen production and suppressing water formation. Furthermore, adding water to the methanol sample may also help the hydrogen production process by impeding reaction 4 and maintain more H (or D) atoms on the BBO rows.

Their results are significant for research of photocatalytic hydrogen formation of titanium dioxide. The mechanism of hydrogen formation from photocatalysis of methanol on TiO2 (110) can be served as a basis for further study and analysis of hydrogen formation by photocatalytic process of metal doped photocatalyst (TiO2), and also provide evidences and clues for development of new catalysts in future.

Source: J. Am. Chem. Soc., 2013, 135 (28), 10206–10209