Titanium dioxide is the most studied photocatalytic material because of its abundance, non-toxicity, stability and high activity. Nevertheless, electron-hole recombination is the biggest problem limiting its efficiency. Several approaches have been previously explored to improve charge separation, including structural modification, doping, or by formation of heterostructures. In this contribution, we highlight the use of colloidal materials with control over size, shape and composition to understand fundamentals of photocatalytic reactivity in titania-based materials, and how to exploit this knowledge to improve the activity.<br/>In particular, we show the power of anisotropy in boosting the photocatalytic activity; specifically that H2 production in uniform, 1-dimensional brookite nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to probe excited electron and holes, we demonstrate that the high rates are due to their anisotropic structure, which favors electron-hole separation and efficient carrier utilization. Quantum efficiency 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.<br/>In a second part, we demonstrate how to further tune the photocatalytic activity of brookite rod samples. Their structure and phase purity is controlled through colloidal synthesis, and structure-property relationships are built to describe their unique activity. In these systems, efficiencies in hydrogen production are further tuned and improved, demonstrating that these novel heterostructures can prove promising in harvesting sunlight and converting it into clean fuels and chemical building blocks.

Engineering titania nanostructure to tune and improve its photocatalytic activity

253rd National Meeting (2017)

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