Browsing by Author "Kamal Prakash"

Now showing 1 - 3 of 3

Co(II)-porphyrin-decorated carbon nanotubes as catalysts for oxygen reduction reactions: An approach for fuel cell improvement
(Royal Society of Chemistry, 2017) Piyush Kumar Sonkar; Kamal Prakash; Mamta Yadav; Vellaichamy Ganesan; Muniappan Sankar; Rupali Gupta; Dharmendra Kumar Yadav
The development of high-performance and cost-effective catalysts for the oxygen reduction reaction (ORR) is essential for the advancement of fuel cells. In this work, three different functionalized cobalt porphyrins, meso-tetraphenylporphyrinatocobalt(ii) (CoTPP), meso-tetrakis(4′-hydroxyphenyl)porphyrinatocobalt(ii) (CoTHPP) and meso-tetrakis(4′-carboxy-phenyl)porphyrinatocobalt(ii) (CoTCPP), are prepared. These porphyrins are immobilized non-covalently on multiwalled carbon nanotubes (MWCNTs) and used for the ORR in 0.1 M HClO4, 0.1 M phosphate buffer solution (pH 7.0) and 0.1 M KOH media. The composite materials are characterized by using spectroscopic and electrochemical techniques and their oxygen reduction efficiencies are compared in different media. Kinetic interpretations and hydrodynamic voltammetry (in three media) studies demonstrated that the MWCNT-CoTPP, MWCNT-CoTHPP and MWCNT-CoTCPP composite materials exhibit significant efficiency with decreased overpotential, considerable methanol tolerance and long term operational stability (up to 3000 cycles) for the ORR similar to commercially available platinum carbon (Pt-C) catalysts. These results reveal that the new MWCNT-cobalt porphyrin composite materials can be a potential alternative to the expensive Pt-C catalysts or other commercial cathode materials in fuel cells. © 2017 The Royal Society of Chemistry.
Electrochemical sensing of rifampicin in pharmaceutical samples using meso-tetrakis(4-hydroxyphenyl)porphyrinato cobalt(II) anchored carbon nanotubes
(Springer Netherlands, 2018) Piyush Kumar Sonkar; Mamta Yadav; Kamal Prakash; Vellaichamy Ganesan; Muniappan Sankar; Dharmendra Kumar Yadav; Rupali Gupta
Abstract: In this work, an electrochemical sensing platform is prepared for rifampicin determination based on multiwalled carbon nanotubes (MWCNTs) modified with meso-tetrakis(4-hydroxyphenyl)porphyrinato cobalt(II) (CoTHPP) nanocomposite (abbreviated as MWCNTs-CoTHPP). The material is characterized by different techniques such as UV–Vis, Fourier transform-infrared, Raman, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. For the electrochemical sensing platform, the nanocomposite, MWCNTs-CoTHPP is immobilized on glassy carbon (GC) electrode (represented as GC/MWCNTs-CoTHPP) and applied for electrochemical recognition of rifampicin. It is found that the GC/MWCNTs-CoTHPP electrode facilitates the electrochemical oxidation of rifampicin with decreased overpotential in 0.1 M acetate buffer (pH 4.7). Further, GC/MWCNTs-CoTHPP exhibits broad calibration range (0.01 µM–5.0 mM), high sensitivity (217 µA mM−1 cm−2), high reproducibility (relative standard deviation = 4.83%, n = 6), and low detection limit (0.008 µM) for rifampicin determination. In addition, this method is successfully applied for real sample (rifampicin capsule) analysis with consistent results. The results suggest that MWCNTs-CoTHPP is a potential candidate for an effective, rapid, and simple electrochemical sensor to detect rifampicin in pharmaceutical formulations. © 2018, Springer Nature B.V.
Insight into efficient bifunctional catalysis: Oxygen reduction and oxygen evolution reactions using MWCNTs based composites with 5,10,15,20-tetrakis(3′,5′-dimethoxyphenyl)porphyrinato cobalt(II) and 5,10,15,20-tetrakis(3′,5′-dihydroxyphenyl)porphyrinato cobalt(II)
(Elsevier Ltd, 2020) Mamta Yadav; Piyush Kumar Sonkar; Kamal Prakash; Vellaichamy Ganesan; Muniappan Sankar; Dharmendra Kumar Yadav; Rupali Gupta
Development of cost-effective, durable, and efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is still required for efficient fuel cells, metal-air-batteries, and water electrolysis. For that purpose we have prepared tetrakis(3′,5′-dimethoxyphenyl)porphyrinato cobalt(II) (CoDMTPP) and 5,10,15,20-tetrakis(3′,5′-dihydroxyphenyl)porphyrinato cobalt(II) (CoDHTPP). Further, multi-walled carbon nanotubes (MWCNTs) based composites of CoDMTPP (MWCNTs-CoDMTPP) and CoDHTPP (MWCNTs-CoDHTPP) are also prepared and characterized through spectroscopy (UV–vis, FTIR, and XPS), microscopy (SEM, TEM with EDAX), X-ray diffraction, thermogravimetry, and electrochemical techniques. The materials, MWCNTs-CoDMTPP and MWCNTs-CoDHTPP are immobilized on glassy carbon (GC) electrodes, represented as GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP. They show efficient ORR activity in acidic, basic, and neutral (pH 7.0 buffer) mediums. Further, both of these electrodes exhibit significant OER activity in 0.1 M KOH, indicating the bifunctional activity in basic medium. Based on the kinetic studies, the presence of –OH in the CoDHTPP is found to enhance the ORR activity. The electrodes, GC/MWCNTs-CoDMTPP and GC/MWCNTs-CoDHTPP exhibit high methanol tolerance capacity. A very small change in onset potential of 12 mV at GC/MWCNTs-CoDMTPP and 3 mV at GC/MWCNTs-CoDHTPP electrodes are observed for the ORR after 3000 continuous potential cycles indicating the high operational stability of the modified electrodes. © 2020 Hydrogen Energy Publications LLC