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.
Owing to outstanding optoelectronic properties, lead halide perovskite nanocrystals (PNCs) are considered promising emitters for next-generation displays. However, the development of pure blue (460-470 nm) perovskite nanocrystal light-emitting diodes (PNC-LEDs), which correspond to the requirements of Rec. 2020 standard, lag far behind that of their green and red counterparts. Here, pure blue CsPb(Br/Cl) 3 nanocrystals with remarkable optical performance are demonstrated by a facile fluorine passivation strategy. Prominently, the fluorine passivation on halide vacancies and strong bonding of Pb–F intensely enhance crystal structure stability and inhibit “particle talking” behaviors under both thermal and electrical conditions. Fluorine-based PNCs with high resistance of luminescence thermal quenching retain 70% of photoluminescent intensity when heated to 343 K, which can be attributed to the elevated activation energy for carrier trapping and unchanged grain size. Fluorine-based PNC-LEDs also exhibit stable pure blue electroluminescence (EL) emission with sevenfold promoted luminance and external quantum efficiencies (EQEs), where the suppression of ion migration is further evidenced by a lateral structure device with applied polarizing potential.
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