Nanocomposites of tantalum-based pyrochlore and indium hydroxide showing high and stable photocatalytic activities for overall water splitting and carbon dioxide reduction

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 H ₂ , whereas In(OH) ₃ was the major active component for water oxidation to produce O ₂ .