Hameed Ullah

Binder-free Fe ₃ O ₄ @C films were fabricated directly on the current collector by adopting a scalable strategy. The improved electrochemical performance exhibited by these nanoarchitectures emphasizes their potential as anodes in energy storage devices.

Development of purposely designed nanostructures is highly desirable for the realization of application-specific functional materials. Here we present the successful preparation of manganese fluoride (MnF2) assemblies as secondary structures made up of primary nanoparticles for application as an anode in conversion-type lithium ion batteries (LIBs). Spherical silica (SiO2) particles were prepared by the so-called Stöber method and utilized as the core of the desired core-shell structure to serve the purposes of a hard template, a precursor in the reaction for synthesis of MnSiF6∙6H2O, and to provide synergy with MnF2 to improve the specific capacities of LIBs. The self-template SiO2@MnOx was prepared by a simple solution method and then transformed into a MnSiF6∙6H2O nanoparticle assembly by reacting with dilute hydrofluoric acid (HF). Although the core (SiO2) and the self-template (SiO2@MnOx) were amorphous, the spherical assembly of MnSiF6·6H2O nanoparticles was crystalline. The nanostructured MnF2 anode material was obtained by moderate heating (380°C) of MnSiF6∙6H2O, aiming to preserve the basic assembly. Crystallographic and microstructural analysis revealed the successful realization of the desired nanostructured MnF2 material. Galvanostatic charge-discharge studies performed on the conversion-type MnF2 anode in LIBs revealed the delivery of a stable and reversible specific capacity of ~380 mAhg-1 for up to 70 cycles at the rate of D/20. The improved performance of the nanostructured MnF2 was attributed to the nanosization and assembly, which allowed fast diffusion of Li+ by reducing its path lengths and mitigated the mechanical degradation during cycling.

Self-assembled architectures of NiF₂ nanoparticles, which were obtained from the thermal decomposition of NiF₂·4H₂O, have performed better as conversion-type cathode materials for lithium-ion batteries. However, due to the lack of systematic insight into the microstructural and morphological evolution of NiF₂·4H₂O, inconsistencies have always existed in its decomposition temperature and pathway. Furthermore, nanoscale NiF₂·4H₂O has never been considered in such studies, let alone its self-assembled architectures and their comparison with bulk counterparts. Additionally, as an interesting thermochemical material, NiF₂·4H₂O lacks experimental evaluation. Here, we present these aspects of self-assembled NiF₂·4H₂O architectures and evaluate the nanostructuring effect on their dehydration mechanism and thermal energy storage capacity. Marked differences were found between the decomposition temperature and mechanism of nano- and bulk NiF₂·4H₂O. Both samples decomposed in two irreversible steps, which involved mostly the loss of water, giving the end product t-NiF_2-x(OH)_x. However, the two samples followed different decomposition pathways. Nano NiF₂·4H₂O converted directly to t-NiF_2-x(OH)_x, while the diaspore form of o-NiF_2-x(OH)_x was found as an intermediate phase in the case of the bulk sample. Furthermore, the thermal energy storage capacity of nanoscale NiF₂·4H₂O was not only larger than that of the bulk but was also comparable to that of other top-performing thermochemical materials.

YFeO₃ films were fabricated on FTO glass via spray pyrolysis for solar fuel (H₂) production through water splitting without any external potential bias. The films demonstrated excellent stability under HER conditions.

Herein, a unique synthetic approach called microemulsion is used to create nickel nanoparticles (Ni-NPs). SEM, TEM, EDX, and XRD techniques were employed for the investigation of morphology and structures of the synthesized material. Electrons from electroactive components are transferred to external circuits by Ni-NPs’ superior electrical conductivity and interconnected nanostructures, which also provide a large number of channels for ion diffusion and additional active sites. The experimental findings showed that as a positive electrode for supercapacitors (SC), Ni-NPs had an outstanding ability to store charge, with a dominant capacitive charge storage of 72.4% when measured at 10 mV/s. Furthermore, at 1 A/g, Ni-NP electrodes exhibit a maximum capacitance of 730 F/g. Further, the Ni-NP electrode retains 92.4% of its capacitance even for 5000 cycles, highlighting possible applications for it in the developing field of renewable energy. The current study provides a new method for producing high-rate next-generation electrodes for supercapacitors.

Due to their beneficial characteristics, 1D nanowires have made significant advancements in different realms due to their large surface area, unique surface chemistry, and tunable transport properties. Herein, a comprehensive study of titanium oxide nanowires from titanium (IV) isopropoxide, with the addition of CNTs in the polymeric membrane, has been conducted to form crystals. This method is quite proficient for nanowire synthetization, incorporated with CNTs and polymeric membranes. Carbon nanotubes (CNTs) were used to enhance their properties with polymeric polyvinylidene fluoride PVDF membrane. The concentration ratio of titanium oxide in PVDF membrane was 1, 3, 5, 10, and 15%. The development of titanium oxide nanowires at the nano level shaped, as the emulsion electrospinning created 1D nanowires. The use of an additive makes the membrane more conductive. FT-IR, XRD, EDS, and SEM techniques were used for size, surface geometry, crystalline nature, blend membrane, and thin film composition determination. Thermal Gravimetric Analysis (TGA) analysis shows that weight loss with temperature increases at optimum level.

Nanocomposites of polyvinylidene fluoride (PVDF) with dimensional (1D) cobalt oxide (Co₃O₄) and f-MWCNTs were prepared successfully by the solution casting method. The impact of 1D Co₃O₄ filler and 1D Co₃O₄/f-MWCNTs co-fillers on the structural, thermal, and electrical behavior of PVDF were studied. The crystal structural properties of pure PVDF and its nanocomposite films were studied by XRD, which revealed a significant enhancement of β-phase PVDF in the resulting nanocomposite films. The increase in β-phase was further revealed by the FTIR spectroscopic analysis of the samples. TG, DTA, and DSC analyses confirmed an increase in thermal stability of PVDF with the addition of nano-fillers as well as their increasing wt.%. From impedance spectroscopic studies, it was found that the DC conductivity of PVDF increases insignificantly initially (up to 0.1 wt.% of nano-fillers addition), but a significant improvement in DC conductivity was found at higher concentrations of the nano-fillers. Furthermore, it was observed that the DC conductivity decreases with frequency. The increase in DC conductivity corresponded to the strong interactions of nano-fillers with PVDF polymer chains.

Here, we report on the fabrication of one‐dimensional (1D) zinc oxide‐tin oxide (ZnO‐SnO₂, ZTO) hollow nanostructures by coaxial electrospinning followed by investigations of their electron transport properties in regular perovskite solar cells (PSCs). The as‐electrospun nanowires (NWs) were obtained as core‐shell nanostructures comprised of polymeric core and metal oxide precursors‐polymer shell. Thermal analysis studies of the as‐electrospun NWs revealed the optimum calcination temperature for complete removal of the polymer and formation of phase pure ZTO. The obtained nanostructured ZTO materials revealed a porous morphology with tubular nanostructures, i.e., NTs. The porous structure of nanoparticles, i.e., NTs in this case, is of particular interest due to the following reasons: (a) structure, particularly 1D, has a profound influence on the electron transport properties, and (b) suitable porosity helps in effective infiltration of perovskite material and hence supports better charge transport at the ZTO‐perovskite interface. The nanomaterials were characterized by Fourier transform infrared (FTIR), diffuse reflectance spectroscopy (DRS), and energy dispersive X‐ray spectroscopy (EDX) to confirm the presence/absence of functional groups, establish band gap energies (E_g), and determine the elemental compositions, respectively. The ZTO NTs were used as electron transport media in the fabrication of perovskite solar cells (PSCs) and established the structure‐property (electron transport) relationships. The highest solar to power conversion efficiency (PCE) of 13.0% (average: 11.90%) was measured for the PSCs based on ZTO NTs obtained by calcination of as‐electrospun NWs at 800°C. It indicates the fact that the calcination temperature influenced the structure which as a result influenced the electron transport property of the material used as ETL in PSCs.