Debabrata Nandi

Maximizing the energy density of aqueous supercapacitors based on MXenes remains a critical challenge due to narrow voltage windows, sluggish or irreversible redox reactions, particularly at extreme and positive potentials. Here, we report a previously unexplored etched manganese–aluminum carbide (EMAX) synthesized via a circular route from waste surgical masks, delivering sustainability alongside performance. EMAX features improved porosity, low work function (2 eV), and a layered architecture with rough surface, while encoding Mn ⁴⁺ /Mn ²⁺ redox sites that underpin fast and reversible pseudocapacitance. In a three–electrode configuration, EMAX achieves superior gravimetric (975 F g ⁻¹ ) and volumetric (1657 F cm ⁻³ ) capacitances. Its intrinsically low work function enables favorable electrode potential alignment (avoiding irreversible anodic oxidation) and effective operation in acidic aqueous electrolytes at extended positive potentials. Consequently, when paired with high‐work‐function nitrogen‐doped graphene, the asymmetric device operates particularly efficiently at 1.6 V, reaching a specific energy of 125.5 Wh kg ⁻¹ and 213 Wh L ⁻¹ and at a specific power of 863 W L ⁻¹ , previously considered unachievable in aqueous electrolyte devices. Together, these results highlight work function engineering, coupled with sustainable carbide synthesis, fast and reversible Mn redox sites, and etching‐induced nano‐architecture, leading to a substantial performance advancement in aqueous asymmetric supercapacitors.

This work utilizes a novel approach leveraging the machine learning (ML) technique to predict the electrochemical supercapacitor performance of graphene oxide nano-rings (GONs) as electrode nanomaterials. Initially, the experimental procedure was carried out to synthesize GO via a modified Hummers method, followed by GONs preparation using the water-in-oil (W/O) emulsion technique. High-resolution transmission electron microscopy (HRTEM) analysis reveals the formation of a typical two-dimensional GO nanosheet and multilayer-GO nano-rings. The X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis results show that the GONs possess similar structural and surface chemistry properties as of GO, with a slight reduction in oxygenous functionalities, enhancing the capacitive behaviours through facile electron migration at the electrode surface. The electrochemical assessment of GO and GONs samples indicates outstanding specific capacitances of 164 F g⁻¹ and 294 F g⁻¹ at 1 mV s⁻¹, showcasing capacitive retention of up to 63% and 60% after 2500 cycles. In addition, four different machine learning models were tested to estimate the role of electrochemical parameters in determining the specific capacitance of GONs.

Bio adsorbents have received tremendous attention due to their eco-friendly, cheap and non-toxic nature. Recently, bio-adsorbent-based membranes have been frequently employed for water treatment. The work reports the preparation of a novel adsorbent membrane from hierarchical zeolite, polyvinyl alcohol, carboxymethyl cellulose and agar. The fabricated membrane was characterized spectroscopically and microscopically with several techniques such as XRD, UTM, TGA, optical microscopy and FT-IR, as well as contact-angle studies. The result showed that the hierarchical-zeolite-loaded membrane is superior in terms of thermal stability, mechanical properties and surface roughness. The fabricated membrane was investigated for its efficiency in the removal of Congo red dye in aqueous conditions. The influence of pH, temperature, contact period and the initial concentration of dye and zeolite loading on the adsorption process are also explored. The adsorption results highlighted the maximum sorption property of Congo red on agar/zeolite/carboxymethyl cellulose/polymer biomembrane was found to be higher (15.30 mg/g) than that of zeolite powder (6.4 mg/g). The adsorption isotherms and kinetic parameters were investigated via Langmuir, Freundlich and pseudo-first order, pseudo-second order and the intraparticle diffusion model, respectively. The adsorption isotherms fitted well for both considered isotherms, whereas pseudo-second order fitted well for kinetics. The thermodynamic parameter, ΔG at 303 K, 313 K and 323 K was −9.12, −3.16 and −0.49 KJ/mol, respectively. The work further explores the antibacterial efficacy of the prepared membrane and its reusability.

The crucial role of face masks is highlighted in our day‐to‐day life during the COVID‐19 pandemic. Polypropylene (PP)‐based disposable face masks are widely used to hold back viral transmission. The discarded masks can create a huge burden of contamination on the environment. The purpose of this work is to recycle and reuse discarded masks to reduce environmental pollution. A simple and innovative technique to recycle surgical masks into composites of higher mechanical strength and antimicrobial properties is explored to reuse in packaging materials and cutleries. The surgical masks composed of PP fibers are recycled to use as a matrix material to reinforce with sisal and hemp fibers. The hot compression molding technique is used to sandwich the PP masks with natural fibers. The tensile strength of the composites is remarkably increased by 197% and 305% for sisal fiber composites and hemp fiber composites, respectively. The tensile elongation also increased to 574% for sisal fiber composites. The resulting composites exhibit notable antimicrobial properties against Staphylococcus aureus, a pathogen responsible for common staphylococcal food poisoning. The composites are found to be suitable to use as food contact cutleries and packaging materials.