| 1. |
- Khan, Inayat Ali, et al.
(författare)
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Shape-control synthesis of PdCu nanoparticles with excellent catalytic activities for direct alcohol fuel cells application
- 2020
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 349
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we described a simple method of PdCu nanoparticles (NPs) synthesis in different morphologies at 120 °C using polyvinylpyrrolidone (PVP) capping agent and ethylene glycol (EG) solvent. Form instrumental characterization it is find out that PdCu NPs are prepared in different morphologies by varying the Pd:Cu weight percent (wt.%) ratios. Nanospheres (NS) are obtained in the absence of Cu, sphere-like NPs having Pd3Cu1 composition are obtained at 3:1 wt.% ratio, cubic NPs having Pd1Cu1 composition are obtained at 1:1 wt.% ratio and cube-like NPs having Pd1Cu3 composition are obtained at 1:3 wt.% ratio. The metals wt.% ratio not only controlled the morphology, but also affected the catalytic activity toward methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) in alkaline media. The PdCu catalyst, in 1:1 wt.% ratio, have demonstrated high specific and mass activities toward MOR (18.07 mA cm−2 and 11.15 A mgPd−1) and EOR (10.24 mA cm−2 and 6.32 A mgPd−1) in alkaline media. Excellent catalytic activity and long-term stability of Pd1Cu1 toward both MOR and EOR is attributed to its stable cubic morphology, composition and synergetic effect, high electrochemical active surface area (ECSA) and PdO reduction at more negative potential. In comparison to the literature, the cubic-PdCu is one of the best electorcatalyst toward MOR and EOR. The cubic-PdCu NPs as anode have potential application in direct alcohol fuel cells owing to their excellent electrochemical performance, stability and cost effectiveness.
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| 2. |
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| 3. |
- Khan, Zakir Zaman, et al.
(författare)
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Pt and Co3O4 supported on ceria and zirconia for the catalytic reduction of N2O in the presence of CO
- 2019
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Ingår i: Solid State Sciences. - : Elsevier. - 1293-2558 .- 1873-3085. ; 98
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Tidskriftsartikel (refereegranskat)abstract
- Ceria (CeO2) and zirconia (ZrO2) supported Pt and Co3O4-based nanocatalysts were synthesized and characterized by different instrumental techniques. The catalysts redox properties and active surface areas were evaluated using temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO) and H2-pulse chemisorption, respectively. The catalysts were tested for the thermal oxidation of carbon monoxide (CO), reduction of nitrous oxide (N2O) and conversion of N2O/CO mixture (1:1 vol%) . In catalytic tests, Pt–Co3O4/CeO2 (10:10%) oxidized CO up to 100% at 25 °C and Co3O4/CeO2 (20%) reduced N2O up to 90% at 320 °C. Moreover, Pt–Co3O4/CeO2 (10:10%) converted N2O/CO mixture to N2/CO2 up to 90% at about 210 °C. The low-temperature catalytic activity of Pt–Co3O4/CeO2 (10:10%) for CO oxidation and N2O/CO mixture redox conversion were attributed to uniform particle size, metals and support proper combination and electron interaction.
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| 4. |
- Khan, Inayat Ali, et al.
(författare)
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Stable and Efficient PtRu Electrocatalysts Supported on Zn-BTC MOF Derived Microporous Carbon for Formic Acid Fuel Cells Application
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Highly efficient, well-dispersed PtRu alloy nanoparticles supported on high surface area microporous carbon (MPC) electrocatalysts, are prepared and tested for formic acid oxidation reaction (FAOR). The MPC is obtained by controlled carbonization of a zincbenzenetricarboxylate metal-organic framework (Zn-BTC MOF) precursor at 950◦C, and PtRu (30 wt.%) nanoparticles (NPs) are prepared and deposited via a polyol chemical reduction method. The structural and morphological characterization of the synthesized electrocatalysts is carried out using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive X-ray (EDX) technique, and gas adsorption analysis (BET). The FAOR performance of the catalysts is investigated through cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). A correlation between high electrochemical surface area (ECSA) and high FAOR performance of the catalysts is observed. Among the materials employed, Pt1Ru2/MPC 950 with a high electrochemical surface area (25.3 m2 g −1 ) consequently showed superior activity of the FAOR (Ir = 9.50 mA cm−2 and Jm = 2,403 mA mg−1 Pt ) at room temperature, with improved tolerance and stability toward carbonaceous species. The superior electrochemical performance, and tolerance to CO-poisoning and long-term stability is attributed to the high surface area carbon support (1,455 m2 g −1 ) and high percentage loading of ruthenium (20 wt.%). The addition of Ru promotes the efficiency of electrocatalyst by offering FAOR via a bifunctional mechanism.
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| 5. |
- Khan, Syed Ishtiaq, et al.
(författare)
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Mononuclear copper(i) complexes of triphenylphosphine and N,N′-disubstituted thioureas as potential DNA binding chemotherapeutics
- 2021
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 45:20, s. 8925-8935
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Tidskriftsartikel (refereegranskat)abstract
- In this work, nine new mixed-ligand complexes with the general formula [CuBr(TPP)2Tu1–9] were synthesized. The copper(I) complexes of triphenylphosphine (TPP) and different N,N′-disubstituted thioureas (Tu) were characterized via spectroscopic techniques including Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H, 13C, and 31P NMR), and single-crystal X-ray diffraction (SC-XRD). The complexes were synthesized via the direct reaction of bromo(tris(triphenylphosphine)copper(I)) [BrCu(PPh3)3] precursor and thiourea ligand solution under ambient conditions. Complexes 1, 2 and 3 crystallized in a triclinic system with the P space group. Each complex is mononuclear, and the copper atom is tetrahedrally attached to two TPP groups through the phosphorous atom, one thiourea molecule through the sulfur atom and one bromine atom. The synthesized compounds were docked with a DNA macromolecule to predict their binding site and it was found that all molecules showed favorable binding to the DNA minor grooves. The DNA interaction studies of the representative complexes demonstrated their efficient DNA binding affinities. Based on the docking and DNA interaction results, complex 7 was found to be the best binder with a docking affinity of 382.2 kJ mol−1 and binding constant of 3.96 × 104 M−1. This compound tends to interact with the minor groove through the bromine atom positioning the side triphenylphosphine rings along the X-axis of the groove while keeping the 1-(2-chlorobenzyl)-3-(3-(trifluoromethyl)phenyl)thiourea ring on the outside.
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| 6. |
- Bhowmick, Sourav, et al.
(författare)
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Physical and electrochemical properties of new structurally flexible imidazolium phosphate ionic liquids
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:38, s. 23289-23300
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Tidskriftsartikel (refereegranskat)abstract
- New structurally flexible 1-methyl- and 1,2-dimethyl-imidazolium phosphate ionic liquids (ILs) bearing oligoethers have been synthesized and thoroughly characterized. These novel ILs revealed high thermal stabilities, low glass transitions, high conductivity and wide electrochemical stability windows up to 6 V. Both anions and cations of 1-methyl-imidazolium ILs diffuse faster than the ions of 1,2-dimethyl-imidazolium ILs, as determined by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The 1-methyl-imidazolium phosphate ILs showed relatively higher ionic conductivities and ion diffusivity as compare with the 1,2-dimethyl-imidazolium phosphate ILs. As expected, the diffusivity of all the anions and cations increases with an increase in the temperature. The 1-methyl-imidazolium phosphate ILs formed hydrogen bonding with the phosphate anions, the strength of which is decreased with increasing temperature, as confirmed by variable temperature 1H and 31P NMR spectroscopy. One of the representative IL, [EmDMIm][DEEP], presented a promising performance at elevated temperatures as an electrolyte in a supercapacitor composed of multiwall carbon nanotubes and activated charcoal (MWCNTs/AC) composite electrodes.
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| 7. |
- Gnezdilov, Oleg I., et al.
(författare)
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Translational and reorientational dynamics of ionic liquid-based fluorine-free lithium-ion battery electrolytes
- 2022
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 345
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Tidskriftsartikel (refereegranskat)abstract
- The translational as well as reorientational mobilities of fluorine-free electrolytes prepared by mixing lithium furan-2-carboxylate Li(FuA) salt with tetra(n-butyl)phosphonium furan-2-carboxylate (P4444)(FuA) ionic liquid are thoroughly investigated. The diffusivity of ions and T1 relaxation of protons belonging to various chemical groups of (P4444)+ and (FuA)− ions and the Li+ ion present in these electrolytes are measured as a function of lithium salt concentration and temperature. The temperature dependence of correlation time for reorientational mobility of various chemical groups of (P4444)+ and (FuA)− ions and the Li+ ion are estimated and used in calculations temperature dependence of the corresponding reorientational rates. It is shown that an increase in the concentration of lithium salt leads to a decrease in both the diffusion coefficients and the reorientation rates for all the chemical groups in concerted way. Activation energy of the reorientational rates for different chemical groups of the organic ions and the Li+ are discussed in details.
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| 8. |
- Hameed, Arslan, et al.
(författare)
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ZIF-12/Fe-Cu LDH Composite as a High Performance Electrocatalyst for Water Oxidation
- 2021
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Layered double hydroxides (LDH) are being used as electrocatalysts for oxygen evolution reactions (OERs). However, low current densities limit their practical applications. Herein, we report a facile and economic synthesis of an iron-copper based LDH integrated with a cobalt-based metal-organic framework (ZIF-12) to form LDH-ZIF-12 composite (1) through a co-precipitation method. The as-synthesized composite 1 requires a low overpotential of 337 mV to achieve a catalytic current density of 10 mA cm−2 with a Tafel slope of 89 mV dec−1. Tafel analysis further demonstrates that 1 exhibits a slope of 89 mV dec−1 which is much lower than the slope of 284 mV dec−1 for LDH and 172 mV dec−1 for ZIF-12. The slope value of 1 is also lower than previously reported electrocatalysts, including Ni-Co LDH (113 mV dec−1) and Zn-Co LDH nanosheets (101 mV dec−1), under similar conditions. Controlled potential electrolysis and stability test experiments show the potential application of 1 as a heterogeneous electrocatalyst for water oxidation.
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| 9. |
- Khan, Inayat Ali, et al.
(författare)
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Effect of Aromaticity in Anion on the Cation–Anion Interactions and Ionic Mobility in Fluorine-Free Ionic Liquids
- 2020
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 124:52, s. 11962-11973
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquids (ILs) composed of tetra(n-butyl)phosphonium [P4444]+ and tetra(n-butyl)ammonium [N4444]+ cations paired with 2-furoate [FuA]−, tetrahydo-2-furoate [HFuA]−, and thiophene-2-carboxylate [TpA]− anions are prepared to investigate the effects of electron delocalization in anion and the mutual interactions between cations and anions on their physical and electrochemical properties. The [P4444]+ cations-based ILs are found to be liquids, while the [N4444]+ cations-based ILs are semi-solids at room temperature. Thermogravimetric analysis revealed higher decomposition temperatures and differential scanning calorimetry analysis showed lower glass transition temperatures for phosphonium-based ILs than the ammonium-based counterparts. The ILs are arranged in the decreasing order of their ionic conductivities as [P4444][HFuA] (0.069 mS cm–1) > [P4444][FuA] (0.032 mS cm–1) > [P4444][TpA] (0.028 mS cm–1) at 20 °C. The oxidative limit of the ILs followed the sequence of [FuA]−> [TpA]−> [HFuA]−, as measured by linear sweep voltammetry. This order can be attributed to the electrons’ delocalization in [FuA]− and in [TpA]− aromatic anions, which has enhanced the oxidative limit potentials and the overall electrochemical stabilities.
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| 10. |
- Khan, Inayat Ali, et al.
(författare)
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Effect of structural variation in biomass-derived nonfluorinated ionic liquids electrolytes on the performance of supercapacitors
- 2022
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 69, s. 174-184
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing interest in sustainable and high performance supercapacitors (SCs) operating at elevated temperatures as they are highly demanded in heat-durable electronics. Here, we present a biomass-derived nonfluorinated ionic liquid (IL) [P4444][HFuA] and its structural analogue [P4444][TpA] as electrolytes for supercapacitors comprising multiwall carbon nanotubes and activated charcoal (MWCNTs/AC) mixed carbon composite electrodes. A detailed investigation of the effect of scan rate, temperature, potential window and orientation of ions on the electrodes surfaces is performed. The supercapacitors exhibited relatively lower specific capacitance for both [P4444][HFuA] and [P4444][TpA] ILs at room temperature. However, the specific capacitance has significantly increased with an increase in temperature and potential window. The equivalent serie resistances of the SCs is deceased with increasing temperatures, which is a result of improved ionic conductivities of the IL electrolytes. In CV cycling at 60 °C, the capacitor with [P4444][HFuA] IL-based electrolyte retained about 90% of its initial capacitance, while the capacitor with [P4444][TpA] IL-based electrolyte retained about 83% of its initial capacitance. Atomistic computations revealed that the aromatic [FuA]− and [TpA]− anions displayed perpendicular distribution that can effectively neutralize charges on the carbon surfaces. However, the [HFuA]− anion exhibited somewhat tilted configurations on the carbon electrode surfaces, contributing to their outstanding capacitive performance in electrochemical devices.
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