Olu Emmanuel Femi

The phosphazene-based COF/PANI/CNT nanocomposite material for supercapacitor applications which shows specific capacitance, energy and power densities are 1142.4 F g ⁻¹ , 39.6 Wh kg ⁻¹ , and 750 W kg ⁻¹ at a current density of 3 A g ⁻¹ respectively.

The study illustrates a circular economy framework in which discarded thermoelectric materials are recycled and transformed into efficient hydrogen evolution reaction (HER) electrocatalysts.

Mixed transition metal oxides exhibit enormous potential as compared to traditional individual metal oxides for energy storage devices such as metal-ion batteries. In the present study, a composite based on a mixed ternary oxide based on zinc and bismuth (ZnBi38O60) and rGO was explored as an anode material for rechargeable Li ion battery. Pristine metal oxide and the composite were thoroughly characterized using different physicochemical techniques and the phase-pure materials were used to study their lithium storage properties. The composite shows a very stable capacity of 415 mAh/g at a current rate of 100 mA/g at the end of 1000 cycles in contrast to pristine metal oxide that reveals a continuous decrease in capacity and drops down to 53 mAh/g after 50 cycles. In-situ diffraction measurements confirm a conversion based alloying mechanism indicating the formation of various compounds such as Bi2O3, ZnO, Bi, BiLi, BiLi3, and ZnLi at different stages of discharge and charge process. The composition and thickness of the solid electrolyte interphase was probed by X-ray photoelectron spectroscopy at different depths of argon sputtering. A full cell with the composite anode and LiCoO2 cathode yields a capacity of 130 mAh/g at a current rate of 100 mA/g after 700 cycles

In thermoelectric (TE) devices, geometry of the TE‐leg has a significant impact on its energy conversion efficiency. TE leg fabrication still relies on traditional methods with regular solid shapes which limits the conversion efficiency. In the present work, different geometries (solid, mesh, hollow, and honeycomb) based on a double‐half‐Heusler (hH) (Ti _1.75 Zr _0.25 Ni _1.5 Fe _0.5 SnSb) high‐entropy alloy are 3D printed using direct ink writing technique. Through the rheological properties, good shear‐thinning characteristics and excellent printability are shown. X‐ray diffraction of the as‐cast and sintered 3D‐printed structures confirms the formation of dominant hH phase. Using infrared imaging, it is revealed that the heat distribution in these structures decreases as an order of as‐cast, solid, mesh, hollow, and honeycomb geometries due to improved surface area to volume ratio respectively. Using X‐ray micro‐computed tomography, the total porosity of the 3D‐printed sample is shown to be around 24.89%. Honeycomb‐shaped structure shows highest temperature gradient (from top to bottom region of sample) of 174 °C as compared to as cast (60.1 °C), which is further validated using finite‐element analysis. In addition, specific energy absorption of 3D‐printed structure is enhanced by 18.5% compared to that of as‐cast structure.

This study presents the synthesis of a green polymer-based nanocomposite by incorporating green CuO nanoparticles into polyaniline (PANI) for the adsorption of Pb (II) ions from contaminated water. The nanocomposite was extensively characterized using FTIR, XRD, BET, SEM-EDX, XPS, and Raman spectroscopy, both before and after Pb(II) adsorption. Optimization studies were performed to assess the effects of key parameters, including pH, adsorbent dosage, and initial ion concentration on the adsorption process. Adsorption isotherms and kinetic models were applied to analyze the experimental data, revealing that the Freundlich isotherm provided the best fit, with a high correlation coefficient (R²) and a (1/n) value less than 1, indicating favorable adsorption conditions. Furthermore, the Avrami and pseudo-first-order kinetic models demonstrated superior fitting compared to other models. The green nanocomposite exhibited outstanding adsorption capacity, highlighting its potential as a sustainable and efficient adsorbent for Pb(II) removal from wastewater.

Polyaniline-based materials have been widely used for supercapacitors due to their outstanding properties, such as high specific capacitance, excellent electrochemical properties, and ease of synthesis methods; however, the short-cycle stability of PANI-based supercapacitors and swelling and shrinking of polymeric structures limit their commercialization. Herein, we synthesized polyaniline (PANI) nanomaterials, which meet high specific capacitance through the chemical oxidative polymerization of aniline with ammonium persulfate (APS) in aqueous salicylic acid. The electrode materials were characterized using UV–vis, TGA, SEM, XRD, BAS-50 W potentiostat, and FTIR instrumentations. The electrical conductivity of the prepared materials was analyzed and found to be relatively high. The electrochemical supercapacitance performance of PANI nanomaterials was characterized using cyclic voltammetry. The polyaniline nanomaterials with a [salicylic acid]/[aniline] molar ratio of 0.8 showed a maximum specific capacitance of 688.5 Fg-1 at a scan rate of 50 mV s⁻¹. Polyaniline nanomaterials were found to exhibit better specific capacitance when compared to bulk polyanilines. Thus, PANI nanomaterials have been found to be a promising alternative for supercapacitor applications.