Glucose is a key intermediate in cellulose photoreforming
for H2production. This work presents a mechanistic investigation
of glucose photoreforming over TiO2and Pt/m-TiO2catalysts. Analysis of the intermediates formed in the process confirmed
the α-scission mechanism of glucose oxidation forming arabinose
(Cn-1sugar) and formic acid in the initial oxidation
step. The selectivity to sugar products and formic acid differed over
Pt/TiO2and TiO2, with Pt/TiO2showing
the lower selectivity to formic acid due to enhanced adsorption/conversion
of formic acid over Pt/TiO2.In situATR-IR
spectroscopy of glucose photoreforming showed the presence of molecular
formic acid and formate on the surface of both catalysts at low glucose
conversions, suggesting that formic acid oxidation could dominate
surface reactions in glucose photoreforming. Furtherin situATR-IR of formic acid photoreforming showed Pt-TiO2interfacial
sites to be key for formic acid oxidation as TiO2was unable
to convert adsorbed formic acid/formate. Isotopic studies of the photoreforming
of formic acid in D2O (with different concentrations) showed
that the source of the protons (to form H2at Pt sites)
was determined by the relative surface coverage of adsorbed water
and formic acid.