The development of flexible and wearable energy storage systems demands zinc-ion batteries with high capacity, mechanical robustness, and long-term electrochemical stability. Vanadium oxide (V6O13.nH2O), with its high theoretical capacity, is a promising cathode material for aqueous and flexible Zn-ion batteries. However, its practical application is hindered by structural instability, vanadium dissolution, and sluggish Zn2+ reaction kinetics, mainly under mechanical deformation. To address these challenges, nanoscale engineering has emerged as an effective strategy to improve both electrochemical performance and mechanical stability. Herein, monoclinic-phase V6O13.nH2O nanobelts are synthesized as robust cathodes, enabling ultrafast Zn2+ kinetics, a medium operating temperature range, and excellent structural stability suitable for flexible battery configurations. The experimental results demonstrated an outstanding electrochemical performance of the V6O13.nH2O nanobelts cathode, delivering a high specific capacity of 400 mAh g−1 at 0.1 A g−1 and retaining ∼95% capacity after 500 cycles at 1 A g−1 at different temperatures. Furthermore, the coin cell configuration maintains 79% capacity after 1500 cycles, whereas the flexible battery exhibits 78% capacity retention after 600 cycles at 10 A g−1. This work highlights vanadium-based cathode design in overcoming limitations of flexible Zn-ion batteries and provides valuable insights into the electrochemical mechanisms governing high-performance electrodes.
The development of phosphors exhibiting negative-thermal expansion (NTE) is urgent for achieving thermally robust luminescence performance of phosphor-converted white light-emitting diodes (pc-WLEDs). The current pc-WLEDs suffer from poor thermal stability, suboptimal color rendering index (CRI) due to blue-light exposure, and high correlated color temperature (CCT). Herein, we developed a promising Sc2Mo3O12:Dy3+ phosphor with bright yellow-white emission upon ultraviolet (UV) and near-UV light excitation. Local structure analysis using extended X-ray absorption fine structure (EXAFS) spectroscopy confirmed the occupancy of Dy3+ ions at octahedral Sc3+ sites. Temperature-dependent in situ X-ray diffraction study revealed a strong NTE effect in Sc2Mo3O12. Temperature-dependent photoluminescence studies demonstrated the excellent luminescence thermal stability of the Sc2Mo3O12:Dy3+ phosphor (91.4%@480 K) due to enhanced structural rigidity and reduced non-radiative decay as a result of thermally induced lattice compaction. The influence of the host's low-temperature phase transition on Dy3+ luminescence was examined under cryogenic temperature conditions. Furthermore, we demonstrated the fabrication of three prototype pc-WLEDs by coating the Sc2Mo3O12:Dy3+ phosphor onto a UV-LED chip with tunable WLED parameters, i.e., CIE, CCT, and luminous efficacy, which strengthens its suitability for commercial lighting. The optical thermal sensing based on charge transfer red-shift and phase transition-induced luminescence has been demonstrated with high relative sensitivity (Sr) values of 2.30 (70 K) and 1.14% K-1 (300 K) across different temperature regimes, from cryogenic to high-temperature conditions, respectively, with visual color tuning. This work highlights the potential of NTE-active hosts in designing pc-WLED phosphors with enhanced thermal stability to advance the commercialization of sustainable WLED lighting, and offers opportunities for flexible thermal sensing in complex environments.
Introduction: The Averrhoa carambola extract was used as a capping and reducing agent to synthesize the CuCeO2 nanoparticles in an eco-friendly method. Materials and Methods: Techniques such as UV-Vis Spectroscopy, XRD, FESEM, EDX, HRTEM, FTIR, and BET were used to characterize the synthesized CuCeO2 nanoparticles. Results: A morphological analysis revealed that the green-synthesized CuCeO2 nanoparticles are spherical, mesopore, monoclinic, and have an average particle size of 14.87 nm. Discussion: The photocatalytic and antibacterial properties of the synthesized CuCeO2 nanoparticles were investigated. CuCeO2 nanoparticles were used to accomplish the complete degradation of the crystal violet dye, illustrating the efficacy of photocatalysts in environmental remediation. The clinical pathogens were tested for antibacterial effectiveness using the agar well method. The CuCeO2 nanoparticles showed strong antimicrobial activity against Gram-positive and Gram-negative bacterial strains of S. aureus, B. subtilis, and E. coli, P. aeruginosa, as well as fungal strains of Candida albicans, respectively. Conclusion: These findings demonstrate the potent antimicrobial and photocatalytic characteristics of CuCeO2 nanoparticles, indicating their potential as a promising material for environmentally remedial photocatalysts and sustainable antimicrobial treatments.
The development of aqueous zinc-ion batteries (AZIBs) is critically hindered by the absence of suitable cathode materials that simultaneously provide rapid Zn2+ diffusion kinetics and high energy density. We report a two-dimensional VO2/VS2 heterojunction nanobelt (VOSHN) as a superior cathode material enhancing specific capacity and longer cycle stability with improved Zn2+ diffusion kinetics. Further electronic features of the heterojunction and their diffusion behavior of Zn2+ in VOSHN are investigated by using DFT calculations. It emphasizes the lower Zn2+ diffusion barrier of 1.32 eV in VOSHN enabling high-rate performance in AZIBs. Consequently, the Zn//VO2/VS2 cell demonstrates a high specific capacity of 351 mAh g(-1) at 0.2 A g(-1) with capacity retention of 93.8% up to 3000 cycles at 3 A g(-1). Furthermore, the Zn//VO2/VS2 battery demonstrates a notable capacity of 44.89 mAh g(-1) with a retention of similar to 71% over 1500 cycles at a high current density of 5 A g(-1). The fascinating VOSHN offers synergistic effect delivering structural robustness, fast-charge transfer, and effective Zn2+ intercalation and hence improves the overall performance of aqueous Zn-ion batteries. This work provides novel routes for the design of 2D heterojunction cathode materials for practical AZIBs.
The development of high-performance electrode materials remains a critical challenge in advancing next-generation pseudocapacitors due to their low electrical conductivity, slow ion diffusion, and structural instability during long-term cycling. The hydrated tungsten oxide (WO3 & centerdot;H2O) has emerged as a promising candidate owing to its layered structure and abundant interlayer water. However, its electrochemical performance is still constrained by limited active sites and inefficient charge-transfer kinetics. To overcome these limitations, Sn doping and controlled phase engineering of WO3 & centerdot;H2O were implemented to enhance the intrinsic electrochemical properties. Sn-doped WO3 & centerdot;H2O was synthesized at different doping concentrations via a simple wet chemical method, followed by annealing to achieve mixed phases of Sn-doped WO3 & centerdot;H2O and WO3. Furthermore, the electrochemical measurements exhibited a significant enhancement in specific capacitance with the doping concentration, i.e., W0, SnW5, and SnW25 delivering specific capacitances of 115 F g-1, 146 F g-1, and 182 F g-1, respectively, at 1 A g-1. Similarly, among the annealed samples (SnW200, SnW400 and SnW600), SnW200 exhibited the highest capacitance of 323 F g-1, demonstrating the synergistic effect of defect modulation and mixed-phase interaction. Eventually, the fabricated quasi-solid-state asymmetric supercapacitor (QSSAS) device achieved 36 F g-1, an energy density of 11 W h kg-1, and a power density of 5795 W kg-1 while retaining 72% capacitance after 10 000 cycles. This work highlights the Sn doping of tungsten oxides as a promising and scalable route for developing durable, high-energy-density pseudocapacitors.
