Showing papers by "Andrews Nirmala Grace published in 2020"
TL;DR: A review on the synthesis, properties and applications of MXenes outlining the current challenges and scope for future research is presented in this article, where the authors focus on the current challenge and scope of future research.
112 citations
TL;DR: In this paper, the most recent advances in the development of fabrication methods, surface modification, and structural engineering to achieve high catalytic activity and practical applicability for hydrogen evolution reaction (HER) are discussed.
66 citations
13 Jul 2020
TL;DR: A novel synthesis of V2NTx (Tx is the surface termination) obtained by the selective removal of “Al” from V2AlN by immersing powders of V 2AlN in the LiF–HCl mixture (salt–acid etching) followed by sonication to obtain V2 NTx (tx = −F, −O) MXene which is then delaminated using the dimethyl sulfoxide solvent.
Abstract: MXenes are the class of two-dimensional transition metal carbides and nitrides that exhibit unique properties and are used in a multitude of applications such as biosensors, water purification, electromagnetic interference shielding, electrocatalysis, supercapacitors, and so forth. Carbide-based MXenes are being widely explored, whereas investigations on nitride-based ones are seldom. Among the nitride-based MXenes obtained from their MAX phases, only Ti4N3 and Ti2N are reported so far. Herein, we report a novel synthesis of V2NT x (T x is the surface termination) obtained by the selective removal of "Al" from V2AlN by immersing powders of V2AlN in the LiF-HCl mixture (salt-acid etching) followed by sonication to obtain V2NT x (T x = -F, -O) MXene which is then delaminated using the dimethyl sulfoxide solvent. The V2NT x MXene is characterized by X-ray diffraction studies, field emission scanning electron microscope imaging, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope imaging. Supercapacitor electrodes are prepared using V2NT x MXenes and their electrochemical performances are examined by cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. The V2NT x MXene electrode exhibits a specific capacitance of 112.8 F/g at a current density of 1.85 mA/cm2 with an energy and power density of 15.66 W h/kg and 3748.4 W/kg, respectively, in 3.5 M KOH aqueous electrolyte. The electrode exhibits an excellent capacitance retention of 96% even after 10,000 charge/discharge cycles. An asymmetric supercapacitor fabricated with V2NT x as a negative electrode and Mn3O4 nanowalls as a positive electrode helps obtain a cell voltage of 1.8 V in aqueous KOH electrolyte.
63 citations
TL;DR: In this article, an asymmetric supercapacitor with Vanadium nitride/Porous carbon as the negative electrode and Ti3C2Tx as the positive electrode is presented.
57 citations
21 Jul 2020
TL;DR: The present study reports the synthesis of a porous Fe-based MOF named MIL-100(Fe) by a modified hydrothermal method without the HF process, demonstrating as an excellent electrocatalyst for the hydrogen evolution reaction investigated in both acidic and alkaline media.
Abstract: The present study reports the synthesis of a porous Fe-based MOF named MIL-100(Fe) by a modified hydrothermal method without the HF process. The synthesis gave a high surface area with the specific surface area calculated to be 2551 m2 g-1 and a pore volume of 1.407 cm3 g-1 with an average pore size of 1.103 nm. The synthesized electrocatalyst having a high surface area is demonstrated as an excellent electrocatalyst for the hydrogen evolution reaction investigated in both acidic and alkaline media. As desired, the electrochemical results showed low Tafel slopes (53.59 and 56.65 mV dec-1), high exchange current densities (76.44 and 72.75 mA cm-2), low overpotentials (148.29 and 150.57 mV), and long-term stability in both media, respectively. The high activity is ascribed to the large surface area of the synthesized Fe-based metal-organic framework with porous nature.
52 citations
TL;DR: An efficient electrode material (Fe (II)S-GQDs) has been prepared by co-doping of sulfur and iron atoms with Graphene quantum dots in this paper.
47 citations
18 Nov 2020
42 citations
TL;DR: In this article, a cuprous oxide encapsulated with graphitic carbon nitride was synthesized and further structural and morphological properties were analyzed by XRD, SEM and BET.
40 citations
TL;DR: A detailed study on the synthesis, properties and electrochemical performance of Vanadium carbide (V4C3) MXene as a supercapacitor electrode is presented in this article.
38 citations
TL;DR: In this article, the fabrication of polythiophene (PTh) grafted 3-dimensional carbon fiber composite by in-situ emulsion polymerization of thiophene monomer on carbon fibre (CF) and with graphene as filler was reported.
36 citations
14 Sep 2020
TL;DR: Cu-based MOFs along with graphene oxide are synthesized and used further for reducing CO2 electrochemically and the results showed that HCOOH was the main product formed through reduction, which is carried out using a cost-effective catalyst for the conversion of CO2 to formic acid than using the commercial electrodes.
Abstract: A recent class of porous materials, viz., metal–organic frameworks (MOFs), finds applications in several areas. In this work, Cu-based MOFs (Cu–benzene-1,3,5-tricarboxylic acid) along with graphene...
TL;DR: In this paper, the fabrication of improved electrode materials for supercapacitor comprise of surfactant doped polypyrrole and carbon materials composites integrated with graphene, amine functionalized multiwalled carbon nanotubes and hybrid carbon assembly.
TL;DR: In this paper, a detailed study has been carried out to know the role of graphene and doped graphene towards capacitance, results proved that doping of graphene showed a synergistic effect thus proving a good electrode for storage applications.
TL;DR: A vanadium nitride xerogel (VNXG) was synthesized by a simple and effective method of ammonialising a vanadium pentoxide xeroglase at a higher temperature as mentioned in this paper.
Abstract: A vanadium nitride xerogel (VNXG) was synthesised by a simple and effective method of ammonialising a vanadium pentoxide xerogel at a higher temperature. Xerogel-structured materials possess salient features such as high surface area, tunable porosity and pore size that result in enhancing the catalytic activity by a fast electron-transport pathway and increase electrolyte diffusion channels. Metal nitrides are reported as promising alternate low-cost counter electrodes to replace the conventional and expensive platinum (Pt) counter electrode. Though few studies are reported on aerogel-based CEs for DSSCs, the present work is the first attempt to synthesize and evaluate the performance of xerogel-structured metal nitrides as counter electrode materials for dye-sensitized solar cells. The synthesized material was well characterized for its structural and morphological characteristics and chemical constituents by photoelectron spectroscopy. Finally, the VNXG was tested for its electrocatalytic performance as a choice of counter electrodes for dye-sensitized solar cells (DSSCs). The photo-current studies were performed under standard 1 SUN, class AAA-simulated illumination with AM1.5G. The consolidated results revealed that the vanadium nitride xerogel exhibited good photocatalytic activity and low charge transfer resistance. This identified it as a promising low-cost counter electrode (CE) material for dye-sensitized solar cells. The photo-current conversion efficiency of the vanadium nitride xerogel CE-based DSSC reached 5.94% comparable to that of the conventional thermal decomposed Pt CE-based DSSC, 7.38% with the same iodide/triiodide electrolyte system. Moreover, the 28 days stability study of VNXG CE DSSCs provided an appreciably stable performance with 37% decrement in the PCE under the same test condition.
TL;DR: This work demonstrates that single crystals of orthorhombic α-MoO3 phase can preferentially grow with a 2D nanoarchitecture via a ball-milling process, followed by heat treatment at elevated temperature.
TL;DR: In this article, the role of capping agent in the formation of Lanthanum hydroxycarbonate (LaOHCO3) spheres was investigated using XRD, FT-IR, SEM, TGA and photoluminescence.