Iron(III) tetraphenylporphyrin chloride (FeTPPCl)-incorporated poly(methyl methacrylate) (PMMA) composite films containing 0–6 wt% FeTPPCl were fabricated by a facile spin-coating technique to systematically investigate their concentration-dependent structural, optical, dielectric, and electrical properties. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) confirmed the successful incorporation of FeTPPCl into the PMMA matrix. The morphological and compositional analyses revealed relatively uniform FeTPPCl dispersion at low loadings, whereas partial aggregation developed at higher concentrations (4–6 wt%). Increasing FeTPPCl content progressively modified the optical response of PMMA, reducing the apparent optical transition energy from 4.84 to 4.11 eV and introducing additional low-energy transitions associated with the Soret and Q bands of the porphyrin macrocycle. The dielectric response was strongly enhanced with FeTPPCl incorporation, resulting in increased polarization and higher dielectric energy density. The AC conductivity increased with both frequency and FeTPPCl concentration. Impedance analysis revealed reduced effective resistive contribution and enhanced interfacial capacitance, accompanied by faster relaxation dynamics, while electric-modulus analysis confirmed non-Debye relaxation with shortened relaxation times. These results demonstrate that controlled FeTPPCl incorporation provides an effective approach for tuning the optical response, dielectric properties, charge transport, and relaxation dynamics of PMMA, highlighting the potential of these lightweight and solution-processable composites for dielectric and optoelectronic applications.
Graphene quantum dots (GQDs) have emerged as promising zero-dimensional carbon nanomaterials due to their tunable photoluminescence, high surface area, chemical stability, and excellent biocompatibility, making them highly attractive for the fluorescence-based chemical and biosensing applications. This review provides a comprehensive and critical analysis of the structural characteristics, synthesis methods, and functionalization strategies that determine the sensing applications of GQDs. The important photophysical processes including quantum size effects, surface state emission, excitation-dependent fluorescence, and energy/electron transfer routes are discussed to establish structure-property-performance relationship in sensing processes. Recent advancements in the GQD-based detection of metal ion, reactive oxygen species, biomolecules, and environmental pollutants are critically reviewed, highlighting performance in the complex matrices. The review concludes with the outlooks on the challenges related to scalable synthesis, reproducibility, defect control, and real-world implementation are discussed, outlines the future opportunities for the rational development of high-performance GQDs-based fluorescence sensing technologies.
The synthesis route is essential for optimising the structural, morphological and electrochemical properties of metal oxide/carbon nanocomposites for energy storage applications. Here, CuO/ZnO@MWCNTs (CZM) nanocomposite were prepared via three different routes, hydrothermal, solgel HMTA-assisted, and solgel NaOH-assisted method to systematically study the effect of synthesis strategy on supercapacitor performance. The formation of CZM hybrid nanocomposite was confirmed successfully by FTIR and XRD. The UV-Vis analysis revealed direct band gaps of 2.66, 3.28 and 2.82 eV for hydrothermal, HMTA-assisted and NaOH-assisted samples respectively. FE-SEM revealed a highly porous interconnected hierarchical morphology with improved particle dispersion of HMTA-assisted route as compared to hydrothermal and NaOH-assisted samples. Surface area analysis is carried out by Brunauer-Emmett-Teller theory (BET). The electrochemical studies revealed that the HMTA-assisted CZM electrode exhibits specific capacitance of 241 F g−1 at 10 A g−1, and energy density of 33.5 Wh kg−1 at power density of 5000 W kg−1, as well as lower charge-transfer resistance and enhanced ion diffusion. AC conductivity analysis showed the highest DC conductivity (1.534 × 10⁻4 S m⁻¹) and lower frequency exponent (s = 0.370), confirming frequency dependent hopping conduction. The synergistic effect of pseudocapacitance from CuO/ZnO, conductive MWCNTs network and porous structure formed by controlled HMTA assisted nucleation and growth is responsible for the enhanced electrochemical performance. These results illustrate the HMTA-assisted solgel route as an efficient strategy to design high-performance CuO/ZnO@MWCNTs nanocomposite for next-generation supercapacitor electrode applications.
Organic materials have gained a tremendous interest as promising cathode materials in lithium-ion batteries (LIBs) in the latest era, due to their high specific capacity, good safety, and flexibility. Their environmental friendliness and sustainability have made them an efficient cathode material in sustainable future batteries. In this study, polyanthraquinone (PAQ) was prepared from monomer anthraquinone (AQ) by crosslinking polymerization. A flexible and free-standing organic composite cathode was fabricated from PAQ and purified single-walled carbon nanotubes (SWCNTs) through simple vacuum filtration. Electrochemical performance of polyanthraquinone-single-walled carbon nanotubes (PAQ-SWCNTs) was compared with the polyanthraquinone-carbon black (PAQ-CB). It revealed the stable intercalation/de-intercalation of lithium ions. PAQ-CB exhibited an initial specific capacity of 232 mAh g−1. In contrast, PAQ-SWCNTs exhibited higher specific capacities of 269 and 229 mAh g−1 at current rates of 0.1 C and 0.5 C respectively, and retained 216 mAh g−1 of initial specific capacity at 0.1 C with almost 100% of columbic efficiency. Two redox peaks were observed during CV, ensuring the two-electron transfer mechanism of PAQ. A prototype flexible battery was assembled and tested against multiple light emitting diodes (LEDs). The stability and performance of these materials classify them as a great alternative of traditional cathode material.
The electrical properties of PEDOT:PSS are constrained by the morphology of the polymer chains and the insulating effects of PSS. Enhancing these characteristics can lead to a substantial improvement in electrical conductivity. In this work, a composite polymer was prepared from PEDOT:PSS (PH1000) and PEO (MW = 1 000 000). The electrical properties of drop casted polymer films show a strong dependence on PEO concentration in the composite material. The highest electrical conductivity of 21391 Sm−1 was achieved at a 70% PEO concentration after thermally treating the film at 200°C for 25 min in ambient atmosphere. Furthermore, the electrical conductivity was improved to 57507 Sm−1, before thermal treatment, by adding 15% of DMSO to the composite polymer. Infrared spectroscopy and EDX measurements indicate to PSS removal during the thermal treatment. Scanning electron microscopy and Raman spectroscopy measurements were performed to gain an insight into the potential structural changes.
