Mesoporous single-crystalline SrNbO2N: Expediting charge transportation to advance solar water splitting

Grain boundaries serve as an interception to the transportation of photo-generated charges (e- and h(+)), severely undermining the photocatalytic performance. In this work, SrNbO2N porous single crystals (PSCs) free of grain boundaries have been synthesized, which deliver exceptionally high photocatalytic activity and stability for water oxidation reactions. The removal of grain boundaries warrants fast charge transportation, reducing the risks of charge recombination. The high porosity of PSCs supplies ample inner surface to carry out catalytic reactions. Deposited with a proper cocatalyst, SrNbO2N PSCs can photocatalyze water oxidation into O-2 with apparent quantum efficiency (AQE) as high as 5.64% at 420 +/- 20 nm. The high activity is also exemplified by integrating SrNbO2N PSCs into a Z-scheme system which can split water into H-2 and O-2 in stoichiometry under simulated solar insolation. These findings not only prove that PSCs expedite charge migration, triggering a high activity for photocatalytic reactions, but also enliven more attention upon traditional materials that hold the potential for solar energy conversions.

Automated summary

In this study, grain boundary-free SrNbO2N porous single crystals (PSCs) were synthesized, exhibiting exceptional photocatalytic activity and stability for water oxidation reactions. The removal of grain boundaries allows for fast charge transportation and reduces charge recombination risks. The high porosity of PSCs provides ample surface for catalytic reactions. With the addition of a proper cocatalyst, SrNbO2N PSCs achieved a high apparent quantum efficiency of 5.64% at 420 +/- 20 nm. Furthermore, integration of SrNbO2N PSCs into a Z-scheme system demonstrated the capability to split water into H-2 and O-2 under simulated solar insolation. These findings highlight the potential of traditional materials for solar energy conversions.