LaNbON2 mesoporous single crystals with expedited photocarrier separation for efficient visible-light-driven water redox reactions

Combining structural coherence and large porosity, semiconducting porous single crystals (PSCs) warrant a great potential as photocatalysts. High photocarrier mobility can be realized in PSCs because of a deficiency in grain boundaries, which in turn greatly alleviates photocarriers’ recombination. The large porosity of PSCs not only provides plenty of accessible surfaces to accommodate catalytic reaction sites but also fortifies photon-matter interplay by reflecting and scattering photons. In this work, taking LaNbON 2 PSCs as an example, we demonstrate the importance of PSCs in activating otherwise almost inactive photocatalyst. Compared to conventional inert LaNbON 2 , LaNbON 2 PSCs exhibit exceptional activity for photocatalytic water redox reactions, delivering a high apparent quantum efficiency, i.e. 6.3% and 10.2% at 420 ± 20 nm for H 2 - and O 2 -evolution reactions, respectively. A Z-scheme system containing LaNbON 2 PSCs has succeeded in overall water splitting (H 2 /O 2 molar ratio 2:1) with high stability under visible light illumination (λ ≥ 420 nm).