Fluorine Passivated Perovskite SrNbO2N Photocatalyst for Robust Sunlight-Driven Water Splitting

SrNbO 2 N is a promising narrow-bandgap semiconductor for sunlight-driven water splitting but is generally subject to insufficient photocarrier separation and severe photocorrosion. Here, the targeted single-crystalline SrNbO 2 N nanobelts are passivated by consecutive annealing in O 2 and N 2 /NH 4 F to approach the right N/O ratio (1/2) and anion content (O + N = 60 at%). The passivation measures lead to both a low concentration (≈2.2 × 10 15 cm −3 ) of defects including V O , Nb 3+ , Nb 4+ for efficient photocarrier separation and unique fluorine-rich, nitrogen-poor surface with low surface energy for high stability against photocorrosion. Notably, the passivated SrNbO 2 N nanobelts deliver the highest values of photocurrent density of 4.5 mA cm −2 at 1.23 V versus RHE and stable photocatalytic (PC) Z-scheme overall water splitting activity of ≈10 µmol h −1 H 2 evolution under AM 1.5G illumination when used as photoanode materials for photoelectrochemical (PEC) water oxidation and the photocatalytic O 2 -evolution moiety, respectively. These findings provide not only an effective guideline to upgrade the activity and stability of SrNbO 2 N but also fresh mechanistic insights into the role of passivation measures.