Lanthanide Tantalum Perovskite Oxynitrides for Photocatalytic Water Splitting: Exploring Beyond Lanthanum

Photocatalytic overall water splitting (POWS) is a developing method of green hydrogen production that utilises light as an energy source. Lanthanide tantalum perovskite oxynitrides (LnTaON 2 , Ln = lanthanide) are promising photocatalyst candidates as their valence and conduction band positions are suitable for POWS and their small bandgaps (1.8–2.4 eV) allow for utilisation of visible light. For lanthanides other than lanthanum, LnTaON 2 perovskites remain underexplored for photocatalytic water splitting, with little work undertaken to optimise their photocatalytic activity and efficiency. In contrast, many successful synthetic variations have been explored to improve the photocatalytic activity of LaTaON 2 , including solid solution formation, morphology control and heterojunction formation. An overview of current work into non-lanthanum LnTaON 2 photocatalysts is provided, along with the successful strategies utilised to improve the photocatalytic performance of LaTaON 2 , providing a toolbox of techniques to apply to non-lanthanum LnTaON 2 photocatalysts to improve their photocatalytic performance in the future.