Department Of Chemistry
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Item Efficient MoS2/V2O5 Electrocatalyst for Enhanced Oxygen and Hydrogen Evolution Reactions(Springer, 2023-04-29T00:00:00) Haldar, Krishna Kanta; Ahmed, Imtiaz; Biswas, Rathindranath; Mete, Shouvik; Patil, Ranjit A.; Ma, Yuan-RonElectrochemical (EC) water splitting is a promising approach for the generation of renewable hydrogen (H2) fuels and oxygen (O2) evolution. Composite structured molybdenum disulphide (MoS2)/vanadium pentoxide (V2O5) with low overpotential is a promising electrocatalyst for anodic and cathodic material for an alternative energy source. We fabricated a flower shape MoS2/V2O5 composite via a hydrothermal approach where V2O5grew on the surface of the MoS2 petals. The unique flower-type composite structure alleviates the surface expansion of electrode material. The electrochemical studies show that the composite possesses good stability with low overpotential and smaller Tafel slope compared to its constituents. It has been found that the MoS2/V2O5 composite exhibits a stable rate performance under the current density of 10�mA�cm?2 which indicates that the MoS2/V2O5 composite might be a good candidate for both oxygen and hydrogen evolution reactions.; Graphical Abstract: [Figure not available: see fulltext.] � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item NiS/MoS2 Anchored Multiwall Carbon Nanotube Electrocatalyst for Hydrogen Generation and Energy Storage Applications(John Wiley and Sons Inc, 2023-04-05T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Iqbal, Muzahir; Roy, Ayan; Haldar, Krishna KantaAlthough sulfide-based materials are known to be efficient catalysts for oxygen evolution reactions (OER), hydrogen evolution reactions (HER), and supercapacitor applications, improving the catalytic activity of sulfide materials for both electrochemical water splitting and supercapacitors remains a challenging problem. Here, an easy and one-step integrated methodology is implemented to develop NiS/MoS2 anchored multiwall carbon nanotubes (MWCNT/NiS/MoS2) catalysts that can effectively and robustly catalyze both the HER and OER. The MWCNT/NiS/MoS2 hybrid composite offers the lowest overpotential of 201 mV and 193 mV to achieve a current density of 10 mA/cm2 and ?10 mA/cm2 with a small Tafel slope of 58 mV/dec 41 mV/dec for OER and HER, respectively, in alkaline and acidic conditions. The obtained multi-walled carbon nanotubes anchored with intertwined NiS/MoS2 have a significant number of active sites and defects throughout the structure. The hybrid composite electrode delivered a specific capacitance of >371.45 F/g at 2 A/g in a two-electrode system, along with high energy density of 51.63 Wh/kg (ED) along with the power density (PD) of 953.63 W/kg, and good capacitance retention ?82% after 2000 cycles. Therefore, a tandem electron transfer mechanism between NiS and MoS2 (MoS2?NiS) is believed to have an electrical synergistic effect that promotes both HER and OER activity. This research opens a new path for the construction of multi-component, cheap electrocatalysts that are highly effective for overall water splitting and energy storage applications. � 2023 Wiley-VCH GmbH.Item Access to carbon nanofiber composite hydrated cobalt phosphate nanostructure as an efficient catalyst for the hydrogen evolution reaction(Frontiers Media S.A., 2023-02-23T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Sharma, Rohit; Burman, Vishal; Haldar, Krishna KantaAttractive technology for producing sustainable hydrogen with water electrolyzers was foreseen as one of the most promising ways to meet the increasing demands of renewable resources and electricity storage. Mainly used for the efficient generation of H2, water electrolysis involving hydrogen evolution reactions (HERs) depends on efficient and affordable electrocatalysts. Hydrogen is an effective fuel that can be produced by splitting water. Hence, the search for highly efficient HER catalysts is a major challenge as efficient hydrogen evolution catalysts are sought to replace catalysts such as platinum. Here, we describe a low-cost and highly effective electrocatalyst for the proper incorporation of the HER electrocatalyst with low overpotential, effective charge transfer kinetics, low Tafel slope, and good durability. By using a simple hydrothermal approach to produce Co3(PO4)2.8H2O/CNF, it is possible to attach Co3(PO4)2.8H2O to the surface of carbon nanofibers (CNFs), which also exhibit remarkable HER activity at an overpotential of 133�mV and produce a current density of 10�mA/cm2 and a 48�mV/decade for the Tafel slope. Large electrochemical surface areas and easy charge transfer from Co3(PO4)2.8H2O to the electrode through conductive Co3(PO4)2.8H2O/CNF composites are the reasons for the improved performance of Co3(PO4)2.8H2O/CNF. Copyright � 2023 Ahmed, Biswas, Sharma, Burman and Haldar.Item Graphitic Carbon Nitride Composites with MoO3-Decorated Co3O4Nanorods as Catalysts for Oxygen and Hydrogen Evolution(American Chemical Society, 2021-10-22T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Patil, Ranjit A.; Halder, Krishna Kamal; Singh, Harjinder; Banerjee, Biplab; Kumar, Bhupender; Ma, Yuan-Ron; Haldar, Krishna KantaWe have prepared a graphitic carbon nitride (g-C3N4) composite with MoO3-decorated Co3O4 nanorods (Co3O4/MoO3/g-C3N4) via the hydrothermal approach, and this hybrid material acts as a highly active and durable electrocatalyst for water splitting reactions. This material could fundamentally influence the catalytic processes and performance of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The OER and HER activities of Co3O4-/MoO3-based nanorods are enhanced by blending with conducting support, for example, graphitic carbon nitrides (g-C3N4). The X-ray diffraction pattern and the attenuated total reflectance-Fourier transform infrared data revealed that the as-synthesized nanorods are highly crystalline in nature and are attached to the g-C3N4 support. Transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy studies also affirm the successful heterointerface formation between Co3O4/MoO3 nanorods and g-C3N4. This Co3O4/MoO3/g-C3N4 rod-shaped catalyst is highly stable in comparison to its individual constituent and generates a current density of 10 mA cm-2 at a low overpotential of 206 mV for OER and 125 mV for HER in alkaline and acidic media, respectively. This work could pave the way for developing Co3O4/MoO3/g-C3N4 composite materials as electrocatalysts for overall water splitting reactions. � 2021 American Chemical Society. All rights reserved.