BITS Faculty Publications

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    Improving the longevity of plasmonic SERS-active substrates using functionalized graphene for trace TNT detection
    (Elsevier, 2025-10) Gupta, Raj Kumar
    Silver (Ag) nanostructures have, by far, been the most effective SERS substrates investigated over the last two decades. However, the oxidation-induced instability limits the practical applications of many Ag-based SERS substrates. In this work, we tackle this problem by creating Ag nanostructures (AgNSs) using femtosecond laser ablation and then covering them with octadecylamine functionalized graphene (ODA-Gr) and reduced graphene oxide (r-GO). The laser-induced periodic surface structures (LIPSS) created on silver surfaces, which strengthen localized plasmonic fields, maximized the SERS activity. While r-GO and pristine graphene have been explored for surface modification of SERS substrates, integration of amine-functionalized graphene offers an unexplored route to synergistically maximize the chemical and electromagnetic enhancements. By introducing octadecylamine groups, we increase both TNT adsorption affinity and protect the Ag nanostructures from oxidation, resulting in unprecedented substrate longevity and detection sensitivity. Our findings show that the ODA-Gr-coated AgNSs outperformed the AgNSs (100 nM) and AgNSs/r-GO (10 nM) in terms of sensitivity, reaching a detection limit of 1 nM for trinitrotoluene (TNT). In addition, the ODA-Gr coating dramatically extended the lifespan of the substrate, maintaining ∼54 % of its original SERS intensity after 120 days, as opposed to ∼32 % for r-GO-coated AgNSs and ∼8 % for bare AgNSs under open-air conditions. Long-term stability and improved adsorption efficiency are facilitated by the combined chemical and electromagnetic enhancement mechanisms in the case of AgNSs/ODA-Gr. These results demonstrate the potential of amine-functionalized graphene-coated AgNSs as a reliable and sensitive SERS platform for explosives detection.
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    Prediction and optimization of microhardness and corrosion behaviour of CuNi-Gr composite coatings
    (University of Politennica, 2024) Belgamwar, Sachin U.; Rathore, Jitendra S.
    Graphene nanoplatelets (Gr) as fillers for alloy composite coatings has increased due to their remarkable high aspect ratio and distinctive plate-like structure. Piping, condensers and heat exchangers in seawater systems, desalination plants, marine hardware and boat hulls are expected to exhibit high wear and corrosion resistance. For this purpose, CuNi-Gr composite coatings have been fabricated using electrodeposition technique and investigated their microhardness and anti-corrosion properties. During the electrodeposition of coatings, the various process variables such as pH, current density, Gr concentration and amount of nickel sulfate have been taken into account. To achieve the full potential of CuNi-Gr composite coating in engineering applications, this study optimizes the performance of the CuNi-Gr composite coating using an orthogonal array design of a Taguchi technique. By Taguchi and regression analysis, it was found that the Gr concentration in the electrolyte is the most influencing parameter of the process for microhardness and polarization resistance of the CuNi-Gr composite coatings. It has been observed that the microhardness and polarization resistance of the composite coatings increase with the increase in the Gr content up to 400 mg/L.
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    Remarkable tribo-mechanical, anticorrosion and antibacterial properties of ZnCu/GNPs composite coatings prepared by electro-co-deposition technique
    (Elsevier, 2024-06) Rathore, Jitendra S.; Belgamwar, Sachin U.
    Herein, we report the fabrication of graphene nanoplatelets (GNPs) reinforced zinc-copper (ZnCu) matrix composite coatings on a stainless-steel substrate using electro-co-deposition technique. The influence of varying concentrations of GNPs in the acidic electrolyte bath on the microstructure, chemical composition, phase structure, hardness, wear resistance, corrosion resistance, and antibacterial activity of ZnCu/GNPs composite coating was investigated. The microhardness of the ZnCu/GNPs composite coating with a GNPs concentration of 100 mg/L is compared with pure ZnCu coating, which has a 90 % significant enhancement, while (50 mg/L) has 86 %, and (25 mg/L) has 50 %. Also, ZnCu/GNPs composite coating showed a wear loss of 10 mg for 100 mg/L GNPs sample with an increase in microhardness. The bacterial resistance assays were conducted against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results reveal a notable improvement in the anti-bacterial activity of the ZnCu/GNPs composite coating. The corrosion rate of the ZnCu/GNPs composite coating in 3.5 wt % NaCl solution steadily decreased when the concentration of GNPs in the electrolyte bath was increased to 100 mg/L. These findings hold great potential for various applications, including healthcare settings where preventing healthcare-associated infections is critical, public infrastructure to prolong the lifespan of structures, and marine coatings to protect against corrosion in harsh marine environments.
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    Two dimensional material based sensor for health care applications
    (CRC Press, 2025) Hazra, Arnab
    Following the discovery of graphene, there has been extensive research on 2D materials, leading to a wide range of applications in the healthcare industry due to their unique properties, such as a high surface-to-volume ratio, nanometre-size layered structure, and bandgap tuning capabilities. In this chapter, we have categorized 2D material-based health sensors into three types: (i) Flexible sensors, (ii) Chemical sensors and (iii) Biosensors. Flexible sensors involve stretching or compressing 2D materials on flexible substrates to vary their resistance or capacitance, enabling the detection of body movements and heart rate. The deposition of mono or a few layers of 2D materials on thin, flexible substrates allows for conformal contact-like properties, facilitating proper and easy placement on the skin of the human body. Chemical sensors produce measurable electric signals when a molecule sits on its active layer. Using 2D material as the active layer enhances their sensitivity due to their thin nature and high surface-to-volume ratio. In biosensors, 2D materials are not used for directly sensing biomolecules due to incompatibility with inorganic molecules. Instead, bioreceptor layers are utilized on 2D material to detect the presence of biomolecules. The presence of 2D material provides a planar conducting channel for current transport in biosensors. The sensors discussed in this chapter primarily have field effect transistor device structures and exhibit responses in terms of current and resistance for monitoring human health indicators such as heart rate, glucose level, pH level and early detection of life-threatening diseases such as tuberculosis, cancer and more. This chapter delves into the applications, reliability, scalability, challenges and future applications of 2D materials such as graphene, transition metal dichalcogenides (TMDCs), MXenes and black phosphorus in healthcare systems.
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    Multiscale modelling of fracture in graphene sheets
    (Elsevier, 2022-12) Islam, Md Rushdie Ibne
    Most of the continuum scale processes, such as fracture, plasticity, etc., trace their origin to atomistic scale phenomena. To gain deeper insights into these processes, one needs to understand the behaviour of materials through the lens of multiscale methods. In this manuscript, we study the problem of fracture crack propagation in graphene sheets through a sequential multiscaling technique. The continuum-mechanical smoothed particle hydrodynamics (SPH) is coupled with the atomistic scale molecular dynamics (MD) simulations through proper constitutive modelling — the non-linear material properties and the mechanical equation of state which serve as the inputs to the SPH model are evaluated directly from the MD simulations. Such handshaking ensures that the continuum-scale SPH model is able to faithfully reproduce the atomistic scale stress–strain behaviour until failure. Using a pre-notched continuum scale graphene sheet, we show that the mode-I stress intensity factor obtained from our SPH model agrees well with the published literature. We subsequently study crack propagation in pre-notched graphene sheets, where the influence of the orientation of the notch is evaluated. Lastly, we take the case of a continuum-scale graphene sheet having randomly oriented cracks and identify the changes in the stress–strain behaviour vis-à-vis a pristine graphene sheet.
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    Modeling and Optimization of Graphene-PEN Based Flexible Piezoresistive Pressure Sensor (FPPS) for Enhanced Sensitivity
    (IEEE, 2024-09) Gupta, Navneet
    This paper presents a comprehensive study on the modelling and optimization of a graphene - polyethylene naphthalate (PEN) based flexible piezoresistive pressure sensor (FPPS). Leveraging the unique properties of graphene and PEN substrate, we achieve exceptional sensitivity in pressure detection. The analysis were done using COMSOL Multiphysics 6.0 version. The proposed sensor demonstrates significant promise for application in wearable electronics, healthcare monitoring and human machine interface.
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    Design and comparative analysis of aluminum-BiFeO3-based plasmonic device in the near-infrared region
    (Springer, 2024-05) Arora, Pankaj
    In this work, a nano-plasmonic device based on Aluminum with BiFeO3 (BFO), as a multiferroic oxide with remarkable dielectric properties, is engineered using the transfer matrix method for implementation in an optical communication band for sensing applications. A comparative study is performed between different dielectric materials (e.g., BFO, Silicon, and Indium Phosphide), and the highest Figure of Merit (FOM) is achieved for the surface plasmon resonance sensor with BFO as the intermediate layer. To further increase the binding efficiency of the biomolecules with the sensing surface, a monolayer of 2D nanomaterial, namely Molybdenum disulfide, Graphene, MXene, and Fluorinated Graphene (FG), is added to the surface of the plasmonic device. After a rigorous analysis, FG is found to have the highest FOM of 334°/RIU and sensitivity of 125°/RIU. In summary, our work reveals potential applications for the proposed nano-plasmonic device based on Al-BFO configuration as a new type of supporting material with a monolayer of FG for enhancing biosensing activity.
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    MXene-based gas sensors
    (RSC, 2021-10) Hazra, Arnab
    Recently, a new class of 2D materials called MXenes have attracted massive attention in a variety of applications. The abundant active sites, metallic conductivity, tunable surface chemistry and outstanding stability of MXenes make them desirable for gas sensing applications. In this context, an impactful amount of research has been performed on MXene based sensors and they can be considered one of the potential future materials for gas sensing. In a focused way, properties like high flexibility, convenient solution processability and easy functionalization of MXenes open the door to make their composites with other nanomaterials and provide a new avenue for advanced sensor research. Previously reported reviews on MXenes and their nanocomposites were not fully focused on the gas sensing application and covered a wide area of applications in energy storage, biomedicine, and photocatalysis. In this review, we focused on the latest research and advancement of pristine MXenes and their nanocomposites for the sensing of gases, volatile organic compounds (VOCs) and humidity. In this review, we first investigated the synthesis procedure of pure MXenes from the MAX phase by selective etching with the help of suitable etchants and delaminating agents. Subsequently, the synthesis procedure of MXene nanocomposites with other nanomaterials like metal oxides, polymers, 2D nanomaterials and other sensing materials has been reported. Later on, we briefly discuss the properties of MXenes involved in sensing performance and the modulation of properties after functionalization due to the synergistic effect of both materials. Finally, the detailed sensing performance and related sensing mechanism have been discussed for MXenes and their nanocomposite-based sensors for a variety of gases, VOCs and humidity.
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    Defluoridation studies using graphene oxidebased nanoadsorbents
    (Elsevier, 2021) Raghuvanshi, Smita; Gupta, Suresh
    The groundwater of many developed and developing countries including India has reported excessive fluoride concentrations. Various technologies are being used to remove fluoride from water but still the problem has remained unsolved. Among the available different technologies, adsorption is one of the best methods due to its easy handling, high efficiency, and lower cost. Adsorption technique with the application of nanoadsorbents has become more efficient, as the adsorption capacity is found to increase significantly due to the large surface area provided by the nanoparticles. Since the last few years, nanomaterial-related technologies have gained much attention in the field of water treatment. The previous studies have discussed the possible mechanism for fluoride ion adsorption on nanoparticles. This chapter discusses the possibility of magnesium oxide nanoparticles as adsorbents for the removal of fluoride from wastewater. This chapter demonstrated the use of modified Hummers' method for synthesizing nano-magnesium oxide (n-MgO) and nanocomposites (n-MgO-coated GOs). The developed adsorbents were characterized using various methods such as FTIR, XRD, SEM-EDX, TEM, etc. The effect of various influencing parameters such as initial pH, initial fluoride concentration, adsorbent dosage, and contact time on fluoride adsorption using developed adsorbents was studied. This chapter demonstrated the efficient removal of fluoride ions from aqueous solution using n-MgO and nanocomposites.
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    Hydrogen storage using novel graphene-carbon nanotube hybrid
    (Elsevier, 2023) Ghosh, Sarbani
    Hydrogen storage is an active area of research particularly due to urgent requirements for green energy technologies. In this paper, we study the storage of hydrogen gas molecules in terms of physical adsorption on a carbon-based nanomaterial, i.e., a novel graphene-carbon nanotube hybrid. The novel carbon nanostructures were prepared from pristine nanotubes and graphene sheets using molecular dynamics simulations and hydrogen storage quantified in terms of gravimetric capacity was simulated using grand canonical Monte Carlo Simulations. We found the highest storage capacity of 5.90 wt% at room temperature and 100 bar with high reversibility of operation