Ceria Supported Pt/PtO-Nanostructures: Efficient Photocatalyst for Sacrificial Donor Assisted Hydrogen Generation under Visible-NIR Light Irradiation

摘要

In photocatalysis, imperative photoredox behavior and narrow band gap are important properties to exploit solar light for water splitting reaction. Nanostructured ceria (cerium dioxide/CeO2) with Ce~(3+)/Ce~(4+) (photoredox couple) shows significant enhancement in photocatalytic activity, however, no significant activity for water splitting reaction. The present study mainly focuses on incorporation of Pt on nanostructured mesoporous ceria by wet-impregnation method and its evaluation for donor assisted photocatalytic water splitting reaction. The BET analysis shows much higher surface area (119-131 m~2 g~(-1)) for unmodified as well as Pt modified mesoceria samples as compared to commercial ceria (24.4 m~2 g~(-1)), although structure was not ordered. The incorporation of Pt on mesoceria shows remarkable influence on photocatalytic hydrogen generation activity, and 1 wt % Pt was found to be optimized content, with broader light absorption. This photocatalyst was optimized with respect to photocatalyst dose, use of different sacrificial donors and their concentrations as well as other experimental parameters, with 34 h time course evaluation, yielding cumulative 1.52 mmol of hydrogen, under visible-NIR light irradiation and using ethanol as a sacrificial donor. The XPS, BET and photoluminescence studies imply that the enhanced photocatalytic hydrogen evolution in the case of mesoceria is due to the unison of high surface area, reduced recombination of photogenerated charge carrier and lower Ce~(3+) concentration in the case of mesoceria.