CsPbI3 perovskite quantum dots (QDs) are more unstable over time as compared to other perovskite QDs, owing to ligand loss and phase transformation. The strong red emission from fresh CsPbI3 QDs gradually declines to a weak emission from aged QDs, which PLQY dropped by 93% after a 20 day storage; finally, there is no emission from δ-phase CsPbI3. The present study demonstrated a facile surface treatment method, where a sulfur–oleylamine (S-OLA) complex was utilized to passivate the defect-rich surface of the CsPbI3 QDs and then self-assembly to form a matrix outside the CsPbI3 QDs protected the QDs from environmental moisture and solar irradiation. The PLQY of the treated CsPbI3 QDs increased to 82.4% compared to initial value of 52.3% of the fresh QDs. Furthermore, there was a significant increase in the colloidal stability of the CsPbI3 QDs. Above 80% of the original PLQY of the treated QDs was reserved after a 20 day storage and the black phase could be maintained for three months before transforming to the yellow phase. The introduction of S-OLA induced the recovery of the lost photoluminescence of the nonluminous aged CsPbI3 QDs with time to 95% of that of the fresh QDs. Furthermore, the photoluminescence was maintained for one month. The increase in the stability and photoluminescence are critical for realizing high-performance perovskite-QD-based devices. Therefore, this work paves the way for increasing the performance of perovskite-based devices in the near future.

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Transition metal dichalcogenides (TMDs), transition metal carbides (TMCs), and transition metal oxides (TMOs) have been widely investigated for electrocatalytic applications owing to their abundant active sites, high stability, good conductivity, and various other fascinating properties. Therefore, the synthesis of composites of TMDs, TMCs, and TMOs is a new avenue for the preparation of efficient electrocatalysts. Herein, we propose a novel low-cost and facile method to prepare TMD–TMC–TMO nano-hollow spheres (WS2–WC–WO3 NH) as an efficient catalyst for the hydrogen evolution reaction (HER). The crystallinity, morphology, chemical bonding, and composition of the composite material were comprehensively investigated using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The results confirmed the successful synthesis of the WS2–WC–WO3 NH spheres. Interestingly, the presence of nitrogen significantly enhanced the electrical conductivity of the hybrid material, facilitating electron transfer during the catalytic process. As a result, the WS2–WC–WO3 NH hybrid exhibited better HER performance than the pure WS2 nanoflowers, which can be attributed to the synergistic effect of the W–S, W–C, and W–O bonding in the composite. Remarkably, the Tafel slope of the WS2–WC–WO3 NH spheres was 59 mV dec−1, which is significantly lower than that of the pure WS2 NFs (82 mV dec−1). The results also confirmed the unprecedented stability and superior electrocatalytic performance of the WS2–WC–WO3 NH spheres toward the HER, which opens new avenues for the preparation of low-cost and highly effective materials for energy conversion and storage applications.