3 research outputs found
Engineering titania nanostructure to tune and improve its photocatalytic activity
Photocatalytic pathways could prove crucial to the sustainable production of fuels and chemicals required for a carbon-neutral society. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, we show the efficacy of anisotropy in improving charge separation and thereby boosting the activity of a titania (TiO2) photocatalytic system. Specifically, we show that H-2 production in uniform, one-dimensional brookite titania nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to separately probe excited electrons and holes, we link the high observed reaction rates to the anisotropic structure, which favors efficient carrier utilization. Quantum yield values for hydrogen production from ethanol, glycerol, and glucose as high as 65%, 35%, and 6%, respectively, demonstrate the promise and generality of this approach for improving the photoactivity of semiconducting nanostructures for a wide range of reacting systems
Solar Hydrogen Production by Plasmonic Au–TiO<sub>2</sub> Catalysts: Impact of Synthesis Protocol and TiO<sub>2</sub> Phase on Charge Transfer Efficiency and H<sub>2</sub> Evolution Rates
The activity of plasmonic Au–TiO<sub>2</sub> catalysts for
solar hydrogen production from H<sub>2</sub>O/MeOH mixtures was found
to depend strongly on the support phase (anatase, rutile, brookite,
or composites thereof) as well as on specific structural properties
caused by the method of Au deposition (sol-immobilization, photodeposition,
or deposition–precipitation). Structural and electronic rationale
have been identified for this behavior. Using a combination of spectroscopic
in situ techniques (EPR, XANES, and UV–vis spectroscopy), the
formation of plasmonic Au particles from precursor species was monitored,
and the charge-carrier separation and stabilization under photocatalytic
conditions was explored in relation to H<sub>2</sub> evolution rates.
By in situ EPR spectroscopy, it was directly shown that abundant surface
vacancies and surface OH groups enhance the stabilization of separated
electrons and holes, whereas the enrichment of Ti<sup>3+</sup> in
the support lattice hampers an efficient electron transport. Under
the given experimental conditions, these properties were most efficiently
generated by depositing gold particles on anatase/rutile composites
using the deposition–precipitation technique