Nanocomposites of Tantalum-Based Pyrochlore and Indium Hydroxide Showing High and Stable Photocatalytic Activities for Overall Water Splitting and Carbon Dioxide Reduction

Abstract

Nanocomposites of tantalum-based pyrochlore nanoparticles and indium hydroxide were prepared by a hydrothermal process for UV-driven photocatalytic reactions including overall water splitting, hydrogen production from photoreforming of methanol, and CO_2 reduction with water to produce CO. The best catalyst was more than 20 times more active than sodium tantalate in overall water splitting and 3 times more active than Degussa P25 TiO_2 in CO_2 reduction. Moreover, the catalyst was very stable while generating stoichiometric products of H_2 (or CO) and O_2 throughout long-term photocatalytic reactions. After the removal of In(OH)_3, the pyrochlore nanoparticles remained highly active for H_2 production from pure water and aqueous methanol solution. Both experimental studies and density functional theory calculations suggest that the pyrochlore nanoparticles catalyzed the water reduction to produce H2, whereas In(OH)_3 was the major active component for water oxidation to produce O_2.

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