A dynamic crystal-amorphous interface engineering strategy is proposed to address the intrinsic challenges of sluggish kinetics and structural degradation in vanadium-based cathodes for aqueous zinc-ion batteries (AZIBs). Through spontaneous electrochemical phase transformation, vanadium oxide/vanadium nitride anchored on carbon nanofibers (V 2 O 3 /VN-CNFs) is in situ converted into a vanadium oxide electrode featuring an intimately coupled crystalline/amorphous VO x (c-VO x /a-VO x ) heterointerface. This adaptive structure combines the merits of both phases: the crystalline domains ensure efficient electron conduction and framework stability, while the amorphous regions offer numerous defective sites for rapid Zn 2+ storage and diffusion. The strong coupling between the two phases generates built-in electric fields at the interface, which effectively promote charge transfer and reduce Zn 2+ diffusion barriers, as further elucidated by DFT calculations. Benefiting from this unique architecture, the c-VO x /a-VO x -CNFs cathode achieves a remarkable capacity of 715.3 mAh g −1 at 0.5 A g −1 , excellent rate performance (400.1 mAh g −1 at 100 A g −1 ), and outstanding cycling stability (95.5% retention after 20,000 cycles). This study highlights the promise of electrochemically self-optimized heterointerfaces in advancing high-performance AZIBs.
Indole-3-acetic acid (IAA) is an important plant hormone and its rapid determination is useful for evaluating plant growth and physiological status. In this work, a screen-printed carbon electrode (SPCE) modified with a composite of MXene, gold nanoparticles (AuNPs), and reduced graphene oxide/carbon nanofibers (rGO-CNFs) incorporating an electrospun carbon-nanofiber network was developed for the voltammetric determination of IAA. The composite was characterized by morphological, structural, and chemical analyses. The modified electrode showed a larger electrochemically active area and lower charge-transfer resistance than the bare SPCE. Under optimized conditions, least-squares regression over 0.05–125 µM based on six concentration levels gave a slope of 1.060 ± 0.016 µA µM−1, a limit of detection (LOD) of 12.1 nM, and a limit of quantification (LOQ) of 40.3 nM. In buffered model solutions, the electrode showed acceptable selectivity, fabrication repeatability, and short-term electrochemical stability. These results support the MXene-AuNPs/rGO-CNFs-modified SPCE as a low-cost platform for IAA determination, while validation in real plant matrices remains necessary.
The construction of anode materials for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with a high energy and a long lifespan is significant and still challenging. Here, sulfur-defective vanadium sulfide/carbon fiber composites (D-V5S8/CNFs) are designed and fabricated by a facile electrospinning method, followed by sulfuration treatment. The unique architecture, in which V5S8 nanoparticles are confined inside the carbon fiber, provides a short-range channel and abundant adsorption sites for ion storage. Moreover, enlarged interlayer spacings could also alleviate the volume changes, and offer small vdW interactions and ionic diffusion resistance to store more Na and K ions reversibly and simultaneously. The DFT calculations further demonstrate that sulfur defects can effectively facilitate the adsorption behavior of Na+ and K+ and offer low energy barriers for ion intercalation. Taking advantage of the functional integration of these merits, the D-V5S8/CNF anode exhibits excellent storage performance and long-term cycling stability. It reveals a high capacity of 462 mA h g−1 at a current density of 0.2 A g−1 in SIBs, while it is 350 mA h g−1 at 0.1 A g−1 in PIBs, as well as admirable long-term cycling characteristics (190 mA h g−1/17 000 cycles/5 A g−1 for SIBs and 165 mA h g−1/3000 cycles/1 A g−1 for PIBs). Practically, full SIBs upon pairing with a Na3V2(PO4)3 cathode also exhibit superior performance.
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