Soumabha Bag

Innovative, sustainable recycling and harvesting methods from the electronic-waste are developed and implemented to capture important and valuable materials.

Ion mobility–mass spectrometry unlocks the missing structural dimension by separating identical mass nanocluster isomers through collision cross section into distinct 3 Dimensional peaks.

The formation of NiOOH on the catalyst surface is widely considered to be the active species in electrochemical urea oxidation reactions (UOR). Though in situ‐formed NiOOH species are reported to be more active than the synthesized ones, the mechanistic study of the actual active species remains a daunting task due to the possibility of different phases and instability of surface‐formed NiOOH. Herein, mechanistic UOR aspects of electrochemically activated metallic Ni ₆₀ Nb ₄₀ Nanoglass showing stability toward the γ‐NiOOH phase are reported, probed via in situ Raman spectroscopy, supported by electron microscopy analysis and X‐ray photoelectron spectroscopy in contrast with the β‐NiOOH formation favored on Ni foil. Detailed mechanistic study further reveals that γ‐NiOOH predominantly follows a direct UOR mechanism while β‐NiOOH favors indirect UOR from time‐dependent Raman study, and electrochemical impedance spectroscopy (EIS) analysis. The Nanoglass has shown outstanding UOR performance with a low Tafel slope of 16 mV dec ⁻¹ and stability for prolonged electrolysis (≈38 mA cm ⁻² for 70 h) that can be attributed to the nanostructured glassy interfaces facilitating more γ‐NiOOH species formation and stabilization on the surface. The present study opens up a new direction for the development of inexpensive Ni‐based UOR catalysts and sheds light on the UOR mechanism.

Carbon dots are one of the most promising nanomaterials which exhibit a wide range of applications in the field of bioimaging, sensing and biomedicine due to their ultra-small size, high photostability, tunable fluorescence, electrical properties, etc. However, green carbon dots synthesized from several natural and renewable sources show some additional advantages, such as favorable biocompatibility, wide sources, low cost of production and ecofriendly nature. In this review, we will provide an update on the latest research of green carbon dots regarding their applications in cancer therapy and in the development of electrochemical sensors. Besides, the toxicity assessment of carbon dots as well as the challenges and future direction of research on their anticancer and sensing applications will be discussed.

The interest in application of nanodiamonds as nanotheranostics is increasing rapidly over recent years. The combination of properties, such as high refractive index, low toxicity, inertness, high carrier capacity and rich surface functionalities, as well as unique magneto-optical properties of the nitrogen-vacancy centre, renders fluorescent nanodiamonds superior to other nanomaterials as nanotheranostics. In this review, the current state of research on the applications of nanodiamonds as theranostics where they have been utilised in combination with both diagnostics/imaging and therapy simultaneously is discussed. Firstly, a brief introduction to the current knowledge about the synthesis and properties of nitrogen-vacancy centre in nanodiamonds is given. Then, the underlying principles that are responsible for the magneto-optical properties of nitrogen-vacancy centre are explained. The majority of theranostic applications of nanodiamonds rely on the judicious engineering of their surface with bioactive molecules. In the following section, methods of engineering the surface of nanodiamonds while preserving their colloidal stability and their implication on in vitro and in vivo biocompatibility are described. Subsequently, the recent developments and applications of nanodiamond conjugates as photo-theranostics and non-targeted and targeted theranostics are critically discussed. Co-delivery of specifically tailored nanodiamonds with both diagnostic/imaging and therapeutic features can considerably contribute towards nanotheranostics-based personalized medicine. Graphical Abstract

Despite being studied for nearly 50 years, smallest chemically stable moieties in the metallic glass (MG) could not be found experimentally. Herein, we demonstrate a novel experimental approach based on electrochemical etching of amorphous alloys in inert solvent (acetonitrile) in the presence of a high voltage (1 kV) followed by detection of the ions using electrolytic spray ionization mass spectrometry (ESI MS). The experiment shows stable signals corresponding to Pd, PdSi and PdSi₂ions, which emerges due to the electrochemical etching of the Pd₈₀Si₂₀metallic glass electrode. These fragments are observed from the controlled dissolution of the Pd₈₀Si₂₀melt-spun ribbon (MSR) electrode. Annealed electrode releases different fragments in the same experimental condition. These specific species are expected to be the smallest and most stable chemical units from the metallic glass which survived the chemical dissolution and complexation (with acetonitrile) process. Theoretically, these units can be produced from the cluster based models for the MG. Similar treatment on Pd₄₀Ni₄₀P₂₀MSR resulted several complex peaks consisting of Pd, Ni and P in various combinations suggesting this can be adopted for any metal-metalloid glass.

Despite being researched for nearly five decades, chemical application of metallic glass is scarcely explored. Here we show electrochemical non-enzymatic glucose sensing ability of nickel-niobium (Ni₆₀Nb₄₀) amorphous alloys in alkaline medium. Three different Ni₆₀Nb₄₀ systems with same elemental composition, but varying microstructures are created following different synthetic routes and tested for their glucose sensing performance. Among melt-spun-ribbon, nanoglass and amorphous-crystalline nanocomposite materials, nanoglass showed the best performance in terms of high anodic current density, sensitivity (20 mA cm^-2 mM^-1), limit of detection (100 nM glucose), stability, reproducibility (above five thousand cycles), and sensing accuracy among non-enzymatic glucose sensors involving amorphous alloys. When annealed in vacuum, only the heat-treated nanoglass retained the similar electrochemical-sensing property while the other materials failed to yield desired results. In nanoglass, a network of glassy interfaces, compared to melt-spun-ribbon, is plausibly responsible for the enhanced sensitivity.