BITS Faculty Publications

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Author: search.filters.author.Pande, SurojitSubject: search.filters.subject.Chemistry

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Now showing 1 - 10 of 45
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    A large step down buck converter for small scale hydrogen generation
    (IEEE, 2025-12) Pande, Surojit; Kumar, Rajneesh
    This paper presents a large step-down buck converter topology employing a coupled inductor and a singles-witch configuration to achieve efficient step-down voltage conversion with an extended conversion ratio. The proposed architecture mitigates the limitations of conventional buck converters by leveraging a coupled inductor to enhance voltage gain while maintaining a moderate duty cycle, thereby reducing conduction and switching losses. The developed single-switch topology is validated using MATLAB Simulation and comprehensive theoretical analysis is conducted, including steady-state operation, voltage gain expression, and component stress evaluation representing hydrogen electrolyser as resistive load in steady state
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    Doped nickel-based nanocatalysts for electrochemical water splitting: a review
    (ACS, 2025-10) Pande, Surojit
    The growing demand for clean energy solutions to address fossil fuel depletion and global warming has increased the pace for the search for sustainable alternatives. To address this situation, hydrogen energy is emerging as a promising method due to its zero pollution and high energy density. Electrocatalytic water splitting is a promising technology for large-scale hydrogen production. Generally, electrocatalysts work well for either the HER or the OER, but not both. Developing catalysts that can be efficiently used for overall water splitting is necessary for commercial viability. Nickel-based materials, specifically when doped with metals (e.g., Fe, Co, W, Cu, Ru, and Ir) and nonmetals (e.g., C, F, and P), have shown great potential because of their versatile chemical properties, corrosion resistance, and structural stability. This review provides a comprehensive overview of recent advancements in doped nickel-based electrocatalysts, which focuses on nickel oxides, chalcogenides, phosphides, nitrides, and single-atom catalysts (SACs). It discusses fundamental mechanisms of HER and OER, strategies for enhancing electrocatalytic performance through doping, defect engineering, and electronic structure modulation. It also discusses the effect of nonmetal and metal doping on activity and stability. The review also emphasizes the importance of systematic experimental approaches like doping ratios, accurate surface area corrections, and operando methods to better understand the relationship between electronic structure and electrocatalytic performance. It also highlights the research gaps and the future directions that aim to advance the design of efficient, stable, and cost-effective nickel-based electrocatalysts, which can contribute to the development of sustainable hydrogen energy production.
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    Ce-doped nise nanosheets on carbon cloth for electrochemical water-splitting
    (ACS, 2024-04) Pande, Surojit
    Developing an affordable and efficient electrocatalyst for bifunctional activity is crucial for the advancement of water electrolysis technology. Doping with foreign atoms in electrocatalysts can tune the electronic properties, which further improves the water-splitting process. Herein, we have developed Ce-doped Ni0.85Se as a bifunctional electrocatalyst in an alkaline medium. The hydrothermal method was used to develop a two-dimensional (2D) nanosheet of the Ce-doped Ni0.85Se electrocatalyst. The as-developed pristine and doped electrocatalysts were characterized through various techniques. The optimized Ce0.1Ni0.85Se electrocatalyst represents −0.238 and 1.56 V vs reversible hydrogen electrode as an onset potential for hydrogen and oxygen evolution reactions, respectively, to generate 20 and 50 mA/cm2 current density. The Ce0.1Ni0.85Se electrocatalyst works as a suitable cell in an alkaline medium with 1.73 V to generate 10 mA/cm2 and 24 h stability. The introduction of Ce doping plays a pivotal role in tuning the electronic environment and facilitating a synergistic effect, ultimately improving the overall efficiency. Moreover, the active sites for water splitting were generated by expansion and distortion in the Ni0.85Se lattice. The enhanced specific surface area and porous 2D nanosheets of the doped sample are beneficial for water splitting. The theoretical results also prove that after doping with Ce, the catalyst has zero band gap, optimum Gibbs hydrogen adsorption energy, and an electronic state are the reasons for improved electrocatalytic performance. The actual active sites in the Ce-doped Ni0.85Se electrocatalyst were determined with density functional theory calculations. Therefore, this idea can generate a route for developing a doped electrocatalyst with efficient and stable activity.
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    Gold Nano-colloids impregnated in Langmuir-Blodgett Film of MoS2 flakes as SERS active platform: Fabrication and its application in Malathion detection
    (Elsevier, 2024-07) Pande, Surojit
    The current work focuses on fabrication of Langmuir-Blodgett (LB) films of MoS2 flakes with impregnated gold nano particles (AuNPs) as a noble Surface enhanced Raman Scattering (SERS) active hetero structure. The hot spots created over the heterostructures work as a potent agent for localization of electromagnetic field resulting in high enhancement of Raman Signals. The LB film of MoS2 flakes with and without the AuNPs were thoroughly characterized in our present work. The efficacy of Au–MoS2 substrate as a SERS sensing platform was investigated up to ultrasensitive concentrations using Raman probe molecules. Moreover, the reproducibility and homogeneity of the substrate was also tested with Raman mapping. The as prepared SERS sensing platform was engaged further for detection of Malathion at trace concentrations. The tests to check on service time was also performed. In the contemporary exploration the fabricated substrate reveals its accuracy and effectivity as a SERS sensor. Thus, in future this substrate can be a novel “Nano-Lab on Chip” device for ultrasensitive detections of chemical and bio-chemical composites.
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    Fabrication of Au decorated MoS2 Langmuir Blodgett film as SERS sensing scaffold for detection of thiram in aqueous solution and in carrot peels
    (Elsevier, 2024-10) Pande, Surojit
    This paper is focused on simple fabrication of robust and reproducible SERS active substrate through self-assembly of gold nanoparticles (AuNps) entrapped in the Langmuir Blodgett (LB) film of MoS2 flakes. The as prepared Au-MoS2 substrate can detect SERS signals of 4-Mercapto Pyridine (4-Mpy) molecules at trace concentrations down to 10-12 M. The substrate has been further employed in detecting thiram (TH) both in aqueous solution and in carrot peels (CPls). The limit of detection (LOD) of TH in aqueous medium and in CPls have been estimated to be ∼ 5.18 and 10.16 pM respectively. We believe that the applicability of this SERS active substrate may be extended in the trace detections of explosives, drugs and in diagnostic applications.
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    Fabrication of stable ru-doped ni0.95se nanostructures for photovoltaic coupled electrochemical water splitting in alkaline medium
    (Wiley, 2025-01) Pande, Surojit; Kumar, Rajneesh
    Development of a competent and stable electrocatalyst coupled with photovoltaic system for the generation of green hydrogen, can be a plausible answer to the existing energy crisis. Herein, we have developed Ru doped Ni0.95Se via hydrothermal method as a bifunctional catalyst for overall water splitting coupled with photovoltaic system. The developed pristine and doped samples were thoroughly characterized by various techniques. The pristine Ni0.95Se and the optimized Ru0.1Ni0.95Se system required a potential of −0.470 and −0.318 V vs. RHE, respectively to acquire a current density of 50 mA cm−2 for HER. The rapid kinetics of the optimized Ru0.1Ni0.95Se is illustrated by the Tafel slope wherein the pristine Ni0.95Se has a Tafel slope value of 172.2 mV/dec, and the Ru0.1Ni0.95Se catalyst has 102 mV/dec. The bifunctional electrocatalyst of Ru0.1Ni0.95Se exhibits very high stability (7 days) in an alkaline medium. Density functional calculations show Ru0.1Ni0.95Se has −0.69 mathematical equation value indicating its remarkable stability. To improve the overall activity and stability of the electrocatalyst Ru dopant is introduced as it tunes the electronic environment by generating a synergistic effect between the metal ions and Se2− anions. This work provides an approach for the generation of green hydrogen through water electrolysis coupled with PV.
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    Development of Copper Cobalt Sulfide with Cu : Co Ratio Variation on Carbon Cloth as an Efficient Electrode Material for the Oxygen Evolution Reaction
    (Wiley, 2019-10) Pande, Surojit
    When designing a device for energy conversion, development of a highly active catalyst for OER (oxygen evolution reaction) reaction in alkaline medium is of utmost importance. For energy conversion, herein, we developed copper cobalt sulfide on carbon cloth (CC) using a simple and facile hydrothermal method. A vertically grown 2D sheet-like structure of copper-cobalt sulfide is observed using L-cysteine as a sulfur source. An optimized ratio of copper(II) and cobalt(III) and the best sulfur source are found to boost the electrocatalytic activity of mixed metal thiospinel for OER. Several characterization techniques (XRD, Raman, FESEM, TEM, XPS, and ICP-AES) were used to confirm phase purity, morphology, and composition of copper cobalt sulfides. We have established that 2D nanosheets of CuCo3Sz/CC exhibited superior electrocatalytic performance over bare RuO2 in 1.0 M KOH solution. It is observed that CuCo3Sz/CC need only 105 mV overpotential to generate 5 mA/cm2 current density. CuCo3Sz/CC is very stable and able to produce unaltered current density under an applied potential of 1.615 V vs. RHE for 48 h. Electrochemically active surface area calculation is performed for all catalysts to confirm higher electrocatalytic activity. The catalyst, CuCo3Sz/CC is used in a broad pH region using 0.5 M KOH, saline water, and 0.5 M Na2SO4 electrolyte solution to widen the applicability of water splitting. This work shows an avenue to develop active and durable electrocatalyst for OER without using any noble metal electrocatalyst.
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    Synthesis of one-dimensional RuO2 nanorod for hydrogen and oxygen evolution reaction: An efficient and stable electrocatalyst
    (Elsevier, 2019-01) Pande, Surojit
    RuO2 nanorod (NR), an efficient and stable catalyst for hydrogen and oxygen evolution reaction is developed via wet-chemical route. Initially, a carbon slurry has been prepared using glucose and urea via heating at 140 °C for 6 h. During the preparation of carbon slurry Ru3+ salt has been added to disperse homogeneously. Finally, calcination at 500 °C for 10 h has been performed using homogeneously distributed Ru3+ ion in carbon slurry to get RuO2 NR. The synthesized RuO2 NR has been well characterized using FESEM, TEM, PXRD, and XPS analysis. The average aspect ratio of a single RuO2 rod is ∼4.37. The synthesized RuO2 NR has been used extensively as an electrocatalyst for hydrogen and oxygen evolution reaction. RuO2 NR shows cathodic potential of −130 mV vs. RHE to achieve current density of 10 mA/cm2 during hydrogen evolution reaction. Whereas, for oxygen evolution 1.508 V vs. RHE is required to generate 10 mA/cm2 current density. Electrochemically active surface area and Tafel slope have been calculated to exhibit better activity of RuO2 NR as compared to commercial RuO2. The overall electrocatalysis mechanism has also been discussed in detail.
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    Bifunctional Tungsten-Doped Ni(OH)2/NiOOH Nanosheets for Overall Water Splitting in an Alkaline Medium
    (ACS, 2022-02) Pande, Surojit
    The development of a cost-effective and proficient bifunctional electrocatalyst is highly fascinating. Herein, we have synthesized a tungsten (W6+)-doped vertically grown nanosheet-like structure of Ni(OH)2/NiOOH on carbon cloth for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in KOH solution. Doping with W6+ ions in Ni(OH)2/NiOOH is performed by electrodeposition, followed by the hydrothermal method. Various amounts of the dopant (W6+) are used to confirm the role of W, but the W0.1Ni(OH)2/NiOOH nanosheet shows the highest efficiency in electrocatalysis. The surface composition and the oxidation state of the developed electrocatalyst are confirmed by inductively coupled plasma atomic emission spectroscopy and X-ray photoelectron spectroscopy analyses. After doping, the lattice suffers a tensile strain, which is confirmed by Raman and X-ray powder diffraction analyses. Field emission scanning electron microscopy and transmission electron microscopy analyses confirm the nanosheet morphology of W0.1Ni(OH)2/NiOOH. The electrocatalyst, W0.1Ni(OH)2/NiOOH, has a lower value of overpotential of 56 and 293 mV to obtain current densities of 10 and 50 mA/cm2 for HER and OER, respectively, in a basic medium. The corresponding Tafel slope values are 63.5 and 48.2 mV dec–1 for HER and OER, respectively. In W0.1Ni(OH)2/NiOOH, the W6+ ion is a d0 system that behaves as a strong Lewis acid and helps in electron pulling from Ni2+ ions, which facilitates the formation of Ni3+ ions as an active site for HER and OER. The electron pulling nature of the W6+ ion is further confirmed from Bader’s charge analysis. Moreover, the synergistic effect between Ni2+ and W6+ ions plays an important role in a higher electrocatalytic efficiency. Density functional theory calculations revealed an increase in the Gibbs free energy of H adsorption in the presence of W, suggesting an enhanced HER activity for W0.1Ni(OH)2/NiOOH.
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    Co-Doped Ni9S8 Nanostructures for Electrocatalytic Water Splitting over a Wide pH Range
    (ACS, 2022-07) Pande, Surojit
    As a replacement for renewable energy sources, an earth-abundant electrocatalyst for water splitting is effectively explored. In this work, Ni9S8 and cobalt-doped Ni9S8 nanostructures are fabricated on carbon cloth using the hydrothermal technique. The developed electrocatalysts are characterized through various techniques, for example, powder X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy , the Brunauer–Emmett–Teller method, and inductively coupled plasma atomic emission spectroscopy. Tuning of cobalt doping is performed to obtain the best optimized ratio of Co/Ni for electrocatalytic activity. All the developed materials are used for a water splitting reaction in an alkaline electrolyzer, and Co0.05Ni8.95S8 is an optimized material for both hydrogen and oxygen evolution. The electrocatalyst Co0.05Ni8.95S8 only requires −0.151 V versus RHE (reversible hydrogen electrode) to obtain a 10 mA/cm2 current density in the hydrogen evolution reaction (HER), and in the oxygen evolution reaction (OER), it requires 1.557 V versus RHE to generate a 30 mA/cm2 current density. The corresponding Tafel slope values for the HER and OER are 125 and 49.8 mV/dec, respectively, obtained by using Co0.05Ni8.95S8 electrocatalysts in 1.0 M KOH solution. The stability of Co0.05Ni8.95S8 is also checked, and it is stable for up to 60 and 80 h for the HER and OER, respectively. The cell voltage of 1.89 V is required to generate a 10 mA/cm2 current density for the overall water splitting reaction. The electrocatalyst is also used for the HER and OER in a wide pH range for practical applicability. The overall experimental findings were verified by theoretical calculations, which state that the higher metallic nature of Co-doped Ni9S8 facilitates efficient electrocatalytic activity. The optimum Gibbs free energy and hydrogen and oxygen coverage calculations also prove that the optimized Co0.05Ni8.95S8 electrocatalyst exhibits the best HER and OER activity. Therefore, this work provides a robust electrocatalyst for the electrocatalytic water splitting reaction.