Akter Hossain Reaz

Anion size and ion pairing of ionic liquids critically determine the scaling of energy and power density of hierarchically porous biomass-derived activated carbon supercapacitors.

Reline-assisted synthesis of fcc-hcp Ni/Ni(OH) ₂ nanocatalyst for effective reductive hydrogenation of 4-nitrophenol with 95% efficiency a high rate constant (k = 0.1336 min ⁻¹ ), demonstrating excellent catalytic performance.

Electrodeposition of metallic zinc (Zn) from reverse micellar solutions of cetyltrimethylammonium bromide (CTAB) of different compositions was successfully performed using constant potential electrolysis on copper (Cu) substrate. Electrochemical behavior of ZnSO₄ was investigated in reverse micellar solutions of CTAB on a glassy carbon (GC) electrode by cyclic voltammetric technique and the electroreduction of Zn(II) to Zn(0) was suggested to be an electrochemically irreversible diffusion controlled process. Morphology and microstructure of the electrodeposited Zn films onto a Cu substrate were examined by scanning electron microscopy, while elemental characterizations were carried out by energy dispersive X-ray spectroscopic method and X-ray diffraction technique. Electrodeposition of Zn from reverse micellar solutions occurred with definite homogeneous shapes whereas, inhomogeneous/random gross Zn deposition was obtained from aqueous system. Moreover, morphology of the electrodeposited Zn films obtained from reverse micellar solutions was found to be varied with the variation of composition of reverse micellar solutions of CTAB. The corrosion protective behavior of the electrodeposited Zn films evaluated through electrochemical impedance spectroscopy and potentiodynamic polarization techniques with 3.5 wt% NaCl solution as corrosion media showed that Zn deposits obtained from reverse micellar solutions exhibited better corrosion protection behavior compared to that obtained from aqueous solution.

We present a facile strategy for synthesizing magnetically retrievable carbon-wrapped CNT/Ni nanospheres (C-wrapped CNT/Ni) that enhance the catalytic performance of metals for environmental pollutant reduction. Structural and compositional analyses using X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and field emission scanning electron microscopy (FESEM) confirmed the phase purity, morphology, and structure of the C-wrapped CNT/Ni. XRD, Raman, and EDS data validate the formation of the nanospheres, while FESEM images reveal uniform Ni nanospheres wrapped with a carbon layer through interconnected, evenly dispersed CNTs. Initially, Ni nanoparticles were anchored onto multiwalled carbon nanotubes to form magnetic CNT/Ni nanospheres, which were then coated with a carbon layer to prevent aggregation, improve Ni particle stability, and introduce additional surface functionalities. The catalytic efficacy of C-wrapped CNT/Ni was assessed through the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The reaction rate constant (k_app = 0.6167 min⁻¹) with C-wrapped CNT/Ni is approximately six times higher than that with bare Ni nanospheres (k_app = 0.1056 min⁻¹). This enhanced catalytic activity is attributed to the synergistic effect between the spherical Ni core and the wrapped carbon layer, mediated by the interconnected CNT, which promotes efficient hydride formation. Additionally, C-wrapped CNT/Ni demonstrates exceptional reusability in the 4-NP reduction process. The integration of these features within a single framework suggests its significant potential for diverse engineering and environmental applications.

Researchers have significantly focused on eco-friendly methods for nanomaterial synthesis to reduce the reliance on hazardous chemicals. In light of this, this study presents an eco-friendly, straightforward, alkali-free method for synthesizing iron–manganese (Fe–Mn) binary oxide (FMBO) and their single oxides by adopting a direct gel formation approach using starch. The synthesized materials were characterized through FTIR, FESEM, EDX, and XRD. Based on the characteristics of the synthesized materials, the probable formation mechanism of nanomaterials within the starch matrix via gel formation was comprehensively investigated. The presence of MnO₄ ⁻ resulted in faster gelation than Fe³⁺ owing to its stronger oxidizing properties, leading to a more robust gel network that could stabilize nucleation, control the growth of nanoparticles, and thereby reduce particle agglomeration. The synthesized materials were further employed for the adsorptive removal of arsenic, and the findings demonstrate that FMBO was much more effective than the individual oxides in simultaneously eliminating arsenic species (III and V) with an adsorption capacity of 79 mg g⁻¹ for total arsenic (As(III) + As(V)) owing to its nanostructure, surface characteristics, and synergistic effects of Fe and Mn oxides. Our observation suggests that Mn oxide pre-oxidizes As(III) to As(V), which is then efficiently adsorbed by Fe oxide. This study underscores the potential of starch-based nanomatrices in developing efficient materials with enhanced properties.

Development of efficient and environmentally benign materials is important to satisfy the increasing demand for energy storage materials. Nanostructured transition-metal oxides are attractive because of their variety in morphology, high conductivity, and high theoretical capacitance. In this work, the nanostructured MnO₂ was successfully fabricated using a gel formation process followed by calcination at 400 °C (MNO4) and 700 °C (MNO7) in the presence of air. The suitability of the prepared materials for electrochemical capacitor application was investigated using graphite as an electrode substrate. The chemical, elemental, structural, morphological, and thermal characterizations of the materials were performed with relevant techniques. The structural and morphological analyses revealed to be a body-centered tetragonal crystal lattice with a nano-tablet-like porous surface. The capacitive performances of the MNO4- and MNO7-modified graphite electrodes were examined with cyclic voltammetry and chronopotentiometry in a 0.5 M Na₂SO₄ aqueous solution. The synthesized MNO7 demonstrated a higher specific capacitance (627.9 F g^-1), energy density (31.4 Wh kg^-1), and power density (803.5 W kg^-1) value as compared to that of MNO4. After 400 cycles, the material MNO7 preserves 100% of capacitance as its initial capacitance. The highly conductive network of nanotablet structure and porous morphologies of MNO7 are most likely responsible for its high capacitive behavior. Such material characteristics deserve a good candidate for electrode material in energy storage applications.