LaTaON 2 Mesoporous Single Crystals for Efficient Photocatalytic Water Oxidation and Z-Scheme Overall Water Splitting.

LaTaON ₂ porous single crystals (PSCs), integrating structural coherence and porous microstructures, will warrant promising photocatalytic performance. The absence of grain boundaries in PSCs ensures rapid photocarrier transportation from bulk to the surface, thereby mitigating photocarriers' recombination. Porous microstructures not only provide ample reachable surface to host photochemical reactions but also reinforce photon-matter interactions by additional photon reflection/scattering. Here, we have synthesized LaTaON ₂ PSCs via a topotactic route and show significantly improved photocatalytic performance. Efficient water oxidation into O ₂ has been realized by LaTaON ₂ PSCs with an apparent quantum efficiency as high as 5.7% at 420 ± 20 nm. Stable overall water splitting into stoichiometric H ₂ and O ₂ has also been achieved in a Z-scheme setup using LaTaON ₂ PSCs as the O ₂ evolution photocatalyst. These results not only prove that PSCs facilitate photocarrier migrations, which in turn deliver exceptional photocatalytic performance, but also imply that PSCs are useful to reinvigorate conventional semiconductor photocatalysts toward efficient solar energy conversions.