The importance of metal reducibility for the photo-reforming of methanol on transition metal-TiO2 photocatalysts and the use of non-precious metals

Novel Au/TiO2 photocatalysts for hydrogen production in alcohol–water mixtures based on hydrogen titanate nanotube precursors

“…10(a)) and 80:20 ( Fig. 10(b) [26][27][28][29][30][31][32]35]. At both ethanol concentrations, the 0.5 wt.% Au/TiNTx photocatalysts displayed excellent stability during the tests, as evidenced by the linearity of the H 2 production plots with UV irradiation time.…”

“…We are currently conducting detailed GC analyses of the other reaction products formed during Au/TiO 2 photo-excitation in the different alcoholwater mixtures, with the aim of better understanding the alcohol photo-oxidation pathway and role in promoting H 2 production. This will also allow the relative contributions of alcohol photoreforming and water-splitting to the observed H 2 yields to be determined, and meaningful comparisons to be drawn with prior related studies on the Pd/TiO 2 system [26][27][28][29][30][31][32]. Further photocatalytic tests are also being conducted under visible and full solar excitation, to determine the extent to which the plasmonic effect [35,[46][47][48] can enhance H 2 production rates.…”

“…It is not clear at all from current literature what the optimum alcohol concentration is for H 2 production in the different M/TiO 2 systems, and whether the optimum concentration varies from alcohol to alcohol (alcohols typically used as sacrificial agents are methanol and ethanol, and to a lesser extent ethylene glycol and glycerol). Bowker and co-workers have made the most important contributions in this area to date [10,[26][27][28][29][30][31][32], reporting hydrogen production rates for the photoreforming of a variety of bio-derivable feedstocks over Pd/P25 and Au/P25 under UV excitation. In the Pd/P25 system, H 2 production rates at an alcohol concentration of 1 vol.% were observed to follow the order triols > diols > 2°alcohols > 1°alcohols > 3°alcohols [26,[28][29][30].…”

“…Bowker and co-workers have made the most important contributions in this area to date [10,[26][27][28][29][30][31][32], reporting hydrogen production rates for the photoreforming of a variety of bio-derivable feedstocks over Pd/P25 and Au/P25 under UV excitation. In the Pd/P25 system, H 2 production rates at an alcohol concentration of 1 vol.% were observed to follow the order triols > diols > 2°alcohols > 1°alcohols > 3°alcohols [26,[28][29][30]. From this pattern of reactivity, it was concluded that the sacrificial hole scavenger must have an a-H adjacent to the OH group(s), with the other main by-products of alcohol photoreforming being largely predictable based on the alcohol structure.…”

Hydrogen generation by photocatalytic reforming of potential biofuels: Polyols, cyclic alcohols, and saccharides

“…Studies reported by Li et al on Au encapsulated with TiO 2 , highlighted that the Au role is to promote hydrogen association to leave metal surface by the reduction of protons on the TiO 2 surface [19]. Studies on various metal/TiO 2 systems shows that it is important for the metal to be in its reduced state for hydrogen to evolve [20].…”