Tapati Sarkar

This study develops a sustainable biomass-derived Fe ₃ O ₄ /activated carbon nanocomposite that combines efficient Pb ²⁺ removal with strong electromagnetic wave attenuation (RL _min of −30 dB at 16 GHz).

Silicon-based materials have attracted considerable interest in energy storage owing to their exceptionally high charge storage capacity. However, their widespread application is hindered by inherent limitations, namely substantial volumetric changes and low intrinsic conductivity during repeated charge–discharge cycles. Herein, a three-dimensional composite is fabricated, comprising well-dispersed silicon nanoparticles on an N-doped carbon nanoweb (NCWs) matrix, encapsulated by a carbonized ZIF-67 coating. This specific structural integration results in superior cycling performance through the effective accommodation of volume expansion and enhanced electron transport. Variations in the metal-organic frameworks (MOFs) precursor content significantly influence the electrochemical performance, highlighting the importance of an appropriate amount. This study systematically investigates the critical role of ZIF-67 precursor content on electrochemical performance. By adjusting the MOF content, the specific discharge capacity and the capacity retention at 0.05 A g⁻¹ reach 2453 mAh g⁻¹ and 1479 mAh g⁻¹, respectively. Employing a proper amount of MOF preserves structural integrity during prolonged cycling. Also, it delivers good cycle stability of 854 mAh g-1 even at 1 A g-1 over 500 cycles. In contrast, an insufficient amount of MOF precursor leads to capacity fading, from 765 to below 400 mAh g⁻¹ under the same conditions (at 1 A g-1 over 500 cycles). Furthermore, the rationally designed structure reduces the charge-transfer resistance from 34.6 to 7.7 Ω and yields higher and more stable coefficients of 4.089×10-11 cm2s-1 and 1.181×10-11 cm2 s-1 cm2s-1 for Li+ diffusion throughout the charge-discharge processes.

Rational design of electrode materials with tailored structural and electronic properties is crucial for the development of high-performance supercapacitors. Here, we report a Zn/V co-doping strategy for NiMoO₄ (ZV-NM), which simultaneously induces abundant oxygen vacancies and a phase transformation from the α to the β phase. The synergistic effects of lattice distortion, enhanced redox activity, and improved electrical conductivity collectively endow ZV-NM3 with extraordinary charge storage capabilities, achieving a remarkable specific capacitance of 1423.1 F g⁻¹ (316.24 mA h g⁻¹) at a current density of 0.4 A g⁻¹. When integrated into an asymmetric supercapacitor device (ZV-NM3/NF//GS), this optimized electrode exhibits a specific capacitance of 101 F g⁻¹ at a current density of 0.4 A g⁻¹. It offers a high energy density of 45.4 Wh kg⁻¹ and a power density of 1.31 kW kg⁻¹, while retaining 90.45% of its capacitance after 10 000 charge/discharge cycles. These results highlight the effectiveness of binary doping in engineering vacancy-rich, phase-optimized transition metal oxides for next-generation energy storage applications.