Concern over the economics of accessing fossil fuel reserves, the anthropogenic CO2 emissions and climate change is driving academic and commercial research into sustainable fuels to meet the demands of a rising global population and ensure future energy security. Semiconductor metal oxides have attracted great interest as photocatalytic materials for wide-ranging applications including wastewater depollution, solar fuels via both H2 production and CO2 reduction. A key challenge is the cheap earth-abundant catalysts with improved quantum efficiency and stability, operating under visible light. Mesoporous TiO2 were synthesised via a surfactant-templating method with subsequent thermal processing. Hierarchical macro-mesoporous TiO2 were also prepared via a dual soft-hard templating approach employing colloidal polystyrene nanospheres. Both families of TiO2 semiconductors were promoted by Cu and Pt co-catalysts via wet impregnation. Calcination temperature increased mesopore size and regulated the anatase:rutile phase distribution and corresponding surface area and band gap. Higher thermal processing strongly enhanced photocatalytic activity. Hierarchical macro-meso TiO2 exhibited a close-packed, ordered macropore framework with uniform mesopores, surface areas and a common anatase crystalline phase. Macropore dimensions could be systematically tuned between 270-400 nm. Macro-meso TiO2 exhibited superior photoactivity relative to mesoporous counterparts in solar fuel production. Promotion with Cu further increased activity by formation of mononuclear Cu (II) species at ultra-low loadings (Figure 1) for both meso and macro-meso TiO2. Mesoporous TiO2 offer a valuable testing ground to assess the relative importance of physicochemical and electronic properties upon photocatalytic activity. Novel macro-meso TiO2 with a uniform mesopore structure and tunable macropores has been synthesised. Promotion with co-catalysts significantly enhances the photoactivity of TiO2 materials.

Nanostructured promoted titania photocatalysts for solar fuels

253rd National Meeting (2017)

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