Harsharaj Jadhav - Academia.edu (original) (raw)

Papers by Harsharaj Jadhav

CRC Press eBooks, Jan 5, 2023

Research on Chemical Intermediates

The biogenic synthesis of copper oxide nanoparticles (CuO NPs) from the leaf extract of Alpinia z... more The biogenic synthesis of copper oxide nanoparticles (CuO NPs) from the leaf extract of Alpinia zerumbet was investigated in this protocol. The basic nature of A. zerumbet leaf extract helps in CuO NPs synthesis. The catalytic activity of A. zerumbet-fabricated CuO NPs is explored in water at room temperature only in the presence of NaPTS hydrotrope. The green catalytic protocol is investigated via synthesis of 1,8-dioxooctahydroxanthene. The biogenic leaf extract fabricated CuO NPs are efficiently reactive, stable and recyclable in aqueous solution of sodium p-toluenesulfonate (NaPTS) hydrotrope. CuO/NaPTS proved to be the best catalytic system as synergistic nanotrope in terms of yield and time of reaction in water at room temperature. The green synthetic approach of CuO NPs, greener medium, easy workup and proficient recyclability are advantages in the said protocol. This is first time report of catalytic activity of biogenic CuO NPs in water at room temperature in the presence of NaPTS.

Ceramics International, 2021

Designing an active and reliable electrocatalyst is the urgent need for the desirable improvement... more Designing an active and reliable electrocatalyst is the urgent need for the desirable improvement in direct methanol fuel cells (DMFCs). In recent time, binary metal oxides have shown much attention as possible electrocatalysts for the future DMFCs. Herein, we have reported direct growth of 3D-CuCo 2 O 4 on Nickel foam (NF) by hydrothermal route for electrochemical methanol oxidation. The electrochemical performance was examined by cyclic voltammetry (CV), chronoamperommetry (CA) and electrochemical impedance spectroscopy (EIS) techniques. Electrochemical analysis of 3D-CuCo 2 O 4 exhibits high current density of 112 A g − 1 at scan rate of 10 mV s − 1 and retains 91% of initial current density after 1000 C V cycles. The high electrocatalytic activity of mesoporous 3D-CuCo 2 O 4 is mainly ascribed to the synergetic effect of bimetallic element (Cu and Co), high surface area and enhanced charge-transfer because of direct growth of catalyst on NF. The present synthesis strategy and use of spinel oxides can offer promising feature for the development of non-precious catalysts for DMFCs.

International Journal of Energy Research, 2020

Hybrid metal oxide heterostructures have been considered as ideal and potential anode materials f... more Hybrid metal oxide heterostructures have been considered as ideal and potential anode materials for lithium ion batteries (LIBs) due to their better electrochemical performances, such as reversible capacity, structural stability and electronic conductivity. Herein, we have demonstrated synthesis of NiCo2O4/BiVO4 heterostructures by simple hydrothermal strategy to construct hybrid xNiCo2O4/(1–x)BiVO4 heterostructures with four selected compositions, that is, x = 10%, 20%, 30% and 40%. XRD shows the phases of NiCo2O4 and BiVO4 and FE‐SEM data revealed strong interface coupling between NiCo2O4 nanowires and BiVO4 dendrites. Upon testing for electrochemical properties, the optimized composition of 30%NiCo2O4‐70% BiVO4 showed higher reversible capacity of 408.6 mAh/g at a constant current rate of 0.5 A/g after 1000 cycles with columbic efficiency around 99% suggesting potential electrode material for high‐performance LIBs. The higher capacity is mainly attributed to the large surface area which can provide more channels and locations for fast Li ion intercalation/de‐intercalation into electrode materials. Additionally, improved Li ion storage capacity with superior rate capability of BN‐30 electrode could be attributed to its lower charge‐transfer resistance. The dendritic and nanowire heterostructure novel system with good stable capacity for LIBs is hitherto unattempted.

ECS Meeting Abstracts, 2014

To date, lithium lanthanum titanate (LLTO) of the nominal formula Li3xLa2/3-x 1/3-2xTiO3 with per... more To date, lithium lanthanum titanate (LLTO) of the nominal formula Li3xLa2/3-x 1/3-2xTiO3 with perovskite structure have been considered to be promising solid electrolyte materials for lithium-oxygen battery due to a numerous outstanding advantages such as: (i) a high lithium conductivity at room temperature, (ii) a high lithium diffusion coefficient, (iii) a low electronic conductivity, and (iv) an electrochemical window larger than 4 V. However, the LLTO materials have also suffered from a few disadvantages such as insufficient total conductivity due to the large grain boundary resistance and difficulty in controlling Li+ content and Li+ conductivity of the materials especially after exposure to high annealing temperature. In addition, when the LLTO contacts directly with Li metal, Ti4+ in LLTO can be reduced into Ti3+ by metallic Li leading to increase in the electron conductivity of LLTO. In this study, we investigated the feasibility of application of Al-doped LLTO ceramics with...

Sustainable Energy & Fuels, 2020

Heterostructuring assisted trimetallic transition metal phoshide with in situ generated active si... more Heterostructuring assisted trimetallic transition metal phoshide with in situ generated active sites, exhibits superior catalytic activity towards oxygen evolution reaction in alkaline medium.

ChemCatChem, 2019

Transition metal oxides have attracted attention as promising electrode materials for energy stor... more Transition metal oxides have attracted attention as promising electrode materials for energy storage and conversion devices with high electrochemical activity and stability. In this study, a simple and cost‐effective solvothermal synthesis of rectangular 3D CuCo2O4 hollow tubes have been developed for methanol electro‐oxidation application. Electrochemical analysis shows that CuCo2O4 hollow tubes exhibit superior electrochemical performance in terms of current density and cycling stability, with 75 mA cm−2 and 90 % retention rate after 1000 cycles, respectively. The high electrochemical performances are mainly due to the morphological structure of CuCo2O4 hollow tubes, which possess high surface area and porosity, resulting to a faster electron‐ion transfer, enhanced reactivity and stability. Given that the synthesis of CuCo2O4 hollow tubes involve a facile and cost‐effective technique, the present approach, thus, opens a new era to novel materials for large‐scale processes in diffe...

ChemCatChem, 2019

Finding metal‐free, carbon‐based, highly active, and durable electrocatalyst for oxygen evolution... more Finding metal‐free, carbon‐based, highly active, and durable electrocatalyst for oxygen evolution reaction (OER) is essential for the development of electrochemical energy storage and conversion systems. Herein, we report the synthesis of graphitic carbon nitride (g‐C3N4) nanorods using a hydrothermal method. The transformation of bulk g‐C3N4 (denoted as g‐B‐CN) to g‐C3N4 1D nanorods (denoted as g‐CN) endowed the material with abundant active sites, increased electrochemical active surface area, and enhanced charge transfer. g‐CN exhibited high activity and durability in catalyzing the OER. The optimized g‐CN achieved a current density of 10 mA cm−2 at an overpotential of 316 mV vs. RHE in 1 M KOH, with a Tafel slope of 125 mV dec−1. The high catalytic performance of g‐CN is mainly attributed to the abundantly exposed unique active sites originatingfrom the 1D morphology and the presence of an oxidized pyridinic nitrogen; elucidating the important role of elaborate morphology tailor...

Journal of Industrial and Engineering Chemistry, 2019

Highlights  Low cost and simple fabrication method for the synthesis of CuO is reported.  CuO m... more Highlights  Low cost and simple fabrication method for the synthesis of CuO is reported.  CuO microstructures were successfully electrodeposited on Ni foam.  CuO/Ni@400 showed better activity for electrochemical methanol oxidation and OER.  Stable electrocatalyst after methanol electro-oxidation and OER.

ChemistrySelect, 2019

Designing and synthesis of efficient, highly active with longer stability and earth abundant cata... more Designing and synthesis of efficient, highly active with longer stability and earth abundant catalysts for the oxygen evolution reaction (OER) is urgent need for the electrochemical production of fuels. In this aspect, herein, facile room‐temperature electrodeposited NiCo layered double hydroxide (NiCo‐LDH) is reported as a highly active and stable electrocatalyst for OER in aqueous solution. In alkaline media, as obtained NiCo LDH shows superior electrocatalytic activity towards water oxidation with overpotential of 270 mV at 10 mA/cm2 with low Tafel slope of 61 mV/dec. The 3D NiCo‐LDH network exhibits excellent structural stability for 36 hours in alkaline media. After testing for stability test, the NiCo‐LDH catalyst maintains its hierarchical 3D network with insignificant degradation in the catalytic activity.

Energy, 2018

Tailoring and Exploring the Basicity of Magnesium Oxide Nanostructures in Ionic Liquids for Clais... more Tailoring and Exploring the Basicity of Magnesium Oxide Nanostructures in Ionic Liquids for Claisen-Schmidt Condensation Reaction

Electrochimica Acta, 2018

Herein, a new fabrication method for CNT nanofiber composite (pPC-FP) through non-covalent intera... more Herein, a new fabrication method for CNT nanofiber composite (pPC-FP) through non-covalent interaction between porphyrin monomers with CNTs is reported. This led to the alleviated agglomeration of pristine CNT without acid pre-treatment, producing a highly porous material with high surface area of 444 m 2 /g and narrow pore size distribution for all pPC-FP nanofiber composites. Enhanced performances of pPC-FP3 and pPC-FP5 (CNT nanofiber with porphyrin monomers) were brought about by the enhanced CNT dispersion, hence, better porosity as compared to pPC. Moreover, through the incorporation of porphyrin monomer, M-NeC bond was simultaneously formed and served as a contributor to the excellent capacitive performance of the material, resulting in the highest capacitance of 150 A/cm 2 at 0.25 mAh/cm 2 with 77 A/cm 2 at 2.5 mAh/cm 2. The composites also exhibited stable performance even after cycling at different current densities (0.25e2.5 mAh/cm 2) for 3000 cycles with almost 100% columbic efficiency. Through p-p stacking interaction, the agglomeration was prevented and CNT was aligned along the axis of the polymer which rendered the nanofibers highly porous resulting to a conductive composite material with excellent electrochemical performance.

Journal of Industrial and Engineering Chemistry, 2018

The development of highly efficient, stable and cost-effective electrocatalyst for oxygen evoluti... more The development of highly efficient, stable and cost-effective electrocatalyst for oxygen evolution reaction (OER) is critical. Herein, we report growth of MnCo 2 S 4 flakes on SS-mesh using two-step strategy, and used as an efficient, highly active and stable electrocatalyst for OER under alkaline condition. The free-standing electrocatalyst delivers exceptional stability of 100 h and activity for OER with overpotential of 290 mV at a current density of 10 mA cm À2 in 1 M KOH. The enhanced electrocatalytic performance was supported experimentally by electrochemical impedance spectra and measurement of the electrochemically active surface area. The high electrochemical active surface area and electrical conductivity of MnCo 2 S 4 flakes played an essential role in their high electrocatalytic performance.

Journal of Alloys and Compounds, 2018

Scalable and simple preparation of metal/metal oxide-carbon composite with high specific surface ... more Scalable and simple preparation of metal/metal oxide-carbon composite with high specific surface areas and designated properties are essential for their large scale practical applications. In view of this, we report an ecofriendly deep eutect solvents (DESs) assisted synthesis of Sn/SnO 2 @C hybrid composite. Herein, we have investigated the crucial role of DESs which collectively acts as solvent-precursorreactant system offering an interesting and exciting physicochemical properties and alternative for the conventional solution-based synthesis methods. TEM images reveal that the massive Sn/SnO 2 nanoparticles with average size of 15e20 nm, are uniformly confined in highly layered porous carbon sheets leading to the carbonaceous composite with large surface area of 500 m 2 /g after thermal treatment. It is noteworthy that the excellent electrochemical performance of Sn/SnO 2 @C hybrid composite for supercapacitor electrode material (109.70 mAh/g at 1.42 mA/cm 2 and almost 100% capacitance retention for 5000 cycles) can be attributed to the higher surface area and synergic properties of Sn and SnO 2. Nevertheless, the carbon matrix with a low degree of graphitization can establishes a good electrical contact and also prevents the detachment of nanoparticles during the course of long-term electrochemical reactions. In addition, selection of less toxic component is possible by virtue of compositional versatility of DESs. Thus the use of DESs can bring froth the twin benefits of solvent-precursor-reactant system and cost effective eco-friendly synthesis route which can be applicable for the synthesis of various metal/metal oxide-carbon composites.

Sensors and Actuators B: Chemical, 2018

The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of mo... more The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 m yolk-shelled ZnCo 2 O 4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo 2 O 4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH 3 and NO 2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo 2 O 4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo 2 O 4 microspheres can be further used in other environment monitoring devices.

ACS Sustainable Chemistry & Engineering, 2018

In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reacti... more In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reaction conditions using 1:1 choline chloride-malonic acid was reported. In the presence of DES, the reaction occurred at a lower temperature (500 °C) compared with that of the respective conventional solid-state synthesis of metal oxides and also with the calcination process involving the metal salts, thereby decreasing the overall formation energy. Differential scanning calorimetry revealed a 2-fold decrease in the endo effect of the thermodestruction of DES, which was observed at a low temperature. The structural pathway taken during the phase and morphology formation was investigated by in situ and ex situ X-ray diffraction (XRD) analysis, Raman spectroscopy, and scanning electron microscopy. The in situ XRD results confirmed the presence of high-temperature α-CoV 2 O 6 , which was finally converted to γ-CoV 2 O 6. On account of the metal speciation in DES similar to the bio-template, well-defined octahedral CoV 2 O 6 nanocrystals were obtained, which exhibited a remarkable OER catalytic activity at current density of 10 mA/cm 2 with an overpotential of mere 324 mV, with excellent durability for greater than 24 h. Thus, a designer DES solvent with characteristics of biodegradability, cost-effectiveness, and renewability demonstrates potential for the synthesis of noble-metal-free OER catalysts, which allows the present synthesis route to fit well within the merits of green chemistry.

Dalton transactions (Cambridge, England : 2003), Jan 18, 2017

A new innovative electrode material (Fe-P800) consisting of a metal complex anchored on carbon vi... more A new innovative electrode material (Fe-P800) consisting of a metal complex anchored on carbon via the utilization of iron-porphyrin conjugated microporous polymer (Fe-CMP) was prepared after pyrolyzing at 800 °C. The usage of the polymer with iron-porphyrin repeating units maximized the possible formation of Fe-Nx coordination within the bulk of the sample while the thermal treatment rendered the carbon framework to form a distinct arrangement between metal, nitrogen and carbon with a high surface area of 450 m2 g-1. The formation of the M-N-C bond, confirmed through XPS analysis, established a direct interaction between metal and carbon material. Thus, an indisputable synergistic effect was observed leading to a high capacitance of 182 F g-1 at a current density of 1 A g-1 despite its low metal loading of ∼1%. It also exhibited a highly robust cycling stability of ∼100% capacitance retention even after 5000 cycles (10 A g-1). In this study, a new mechanism was proposed wherein the...

Electrochimica Acta, 2017

Growth of urchin-like ZnCo2O4 microspheres on nickel foam as a binderfree electrode for high-perf... more Growth of urchin-like ZnCo2O4 microspheres on nickel foam as a binderfree electrode for high-performance supercapacitor and methanol electro-oxidation, Electrochimica Actahttp://dx.

New Journal of Chemistry, 2017

Co(OH)2 nanoflakes directly grown on Ni foam using an electrodeposition route exhibit a promising... more Co(OH)2 nanoflakes directly grown on Ni foam using an electrodeposition route exhibit a promising performance for electrocatalytic oxidation of methanol.

Ceramics International, 2017

In this work, we describe the synthesis of hierarchically mesoporous MnCo 2 O 4 microspheres via ... more In this work, we describe the synthesis of hierarchically mesoporous MnCo 2 O 4 microspheres via a urea-assisted co-precipitation method, followed by a post-annealing treatment in air. The stoichiometric amount of urea serves as a self-template to favor the self-assembly of hierarchically well-organized, 3D interconnected precursor carbonate microspheres under optimized reaction conditions. An electrode fabricated from micro/ nano-structured MnCo 2 O 4 delivers an excellent multi-functional electrochemical performance when used in supercapacitors and methanol electro-oxidations. The electrode exhibits a high specific capacitance of 1857 F/g at a 5 mV/s scan rate, and 97% capacitance retention after 5000 cycles. Also, as an electro-catalyst for methanol oxidation, it maintains an optimum current density up to 95 A/g. The superior electrochemical performance might be attributed to its three-dimensional interconnected porous architecture, which offers a rapid ion/ electron transfer, and structural stability. The synthesis method adopted in the present study is simple, controllable, and easy to carry out at a production scale. Furthermore, the superior electrochemical performance of the as-obtained MnCo 2 O 4 microspheres renders them a potential candidate for various energy applications.

CRC Press eBooks, Jan 5, 2023

Research on Chemical Intermediates

The biogenic synthesis of copper oxide nanoparticles (CuO NPs) from the leaf extract of Alpinia z... more The biogenic synthesis of copper oxide nanoparticles (CuO NPs) from the leaf extract of Alpinia zerumbet was investigated in this protocol. The basic nature of A. zerumbet leaf extract helps in CuO NPs synthesis. The catalytic activity of A. zerumbet-fabricated CuO NPs is explored in water at room temperature only in the presence of NaPTS hydrotrope. The green catalytic protocol is investigated via synthesis of 1,8-dioxooctahydroxanthene. The biogenic leaf extract fabricated CuO NPs are efficiently reactive, stable and recyclable in aqueous solution of sodium p-toluenesulfonate (NaPTS) hydrotrope. CuO/NaPTS proved to be the best catalytic system as synergistic nanotrope in terms of yield and time of reaction in water at room temperature. The green synthetic approach of CuO NPs, greener medium, easy workup and proficient recyclability are advantages in the said protocol. This is first time report of catalytic activity of biogenic CuO NPs in water at room temperature in the presence of NaPTS.

Ceramics International, 2021

Designing an active and reliable electrocatalyst is the urgent need for the desirable improvement... more Designing an active and reliable electrocatalyst is the urgent need for the desirable improvement in direct methanol fuel cells (DMFCs). In recent time, binary metal oxides have shown much attention as possible electrocatalysts for the future DMFCs. Herein, we have reported direct growth of 3D-CuCo 2 O 4 on Nickel foam (NF) by hydrothermal route for electrochemical methanol oxidation. The electrochemical performance was examined by cyclic voltammetry (CV), chronoamperommetry (CA) and electrochemical impedance spectroscopy (EIS) techniques. Electrochemical analysis of 3D-CuCo 2 O 4 exhibits high current density of 112 A g − 1 at scan rate of 10 mV s − 1 and retains 91% of initial current density after 1000 C V cycles. The high electrocatalytic activity of mesoporous 3D-CuCo 2 O 4 is mainly ascribed to the synergetic effect of bimetallic element (Cu and Co), high surface area and enhanced charge-transfer because of direct growth of catalyst on NF. The present synthesis strategy and use of spinel oxides can offer promising feature for the development of non-precious catalysts for DMFCs.

International Journal of Energy Research, 2020

Hybrid metal oxide heterostructures have been considered as ideal and potential anode materials f... more Hybrid metal oxide heterostructures have been considered as ideal and potential anode materials for lithium ion batteries (LIBs) due to their better electrochemical performances, such as reversible capacity, structural stability and electronic conductivity. Herein, we have demonstrated synthesis of NiCo2O4/BiVO4 heterostructures by simple hydrothermal strategy to construct hybrid xNiCo2O4/(1–x)BiVO4 heterostructures with four selected compositions, that is, x = 10%, 20%, 30% and 40%. XRD shows the phases of NiCo2O4 and BiVO4 and FE‐SEM data revealed strong interface coupling between NiCo2O4 nanowires and BiVO4 dendrites. Upon testing for electrochemical properties, the optimized composition of 30%NiCo2O4‐70% BiVO4 showed higher reversible capacity of 408.6 mAh/g at a constant current rate of 0.5 A/g after 1000 cycles with columbic efficiency around 99% suggesting potential electrode material for high‐performance LIBs. The higher capacity is mainly attributed to the large surface area which can provide more channels and locations for fast Li ion intercalation/de‐intercalation into electrode materials. Additionally, improved Li ion storage capacity with superior rate capability of BN‐30 electrode could be attributed to its lower charge‐transfer resistance. The dendritic and nanowire heterostructure novel system with good stable capacity for LIBs is hitherto unattempted.

ECS Meeting Abstracts, 2014

To date, lithium lanthanum titanate (LLTO) of the nominal formula Li3xLa2/3-x 1/3-2xTiO3 with per... more To date, lithium lanthanum titanate (LLTO) of the nominal formula Li3xLa2/3-x 1/3-2xTiO3 with perovskite structure have been considered to be promising solid electrolyte materials for lithium-oxygen battery due to a numerous outstanding advantages such as: (i) a high lithium conductivity at room temperature, (ii) a high lithium diffusion coefficient, (iii) a low electronic conductivity, and (iv) an electrochemical window larger than 4 V. However, the LLTO materials have also suffered from a few disadvantages such as insufficient total conductivity due to the large grain boundary resistance and difficulty in controlling Li+ content and Li+ conductivity of the materials especially after exposure to high annealing temperature. In addition, when the LLTO contacts directly with Li metal, Ti4+ in LLTO can be reduced into Ti3+ by metallic Li leading to increase in the electron conductivity of LLTO. In this study, we investigated the feasibility of application of Al-doped LLTO ceramics with...

Sustainable Energy & Fuels, 2020

Heterostructuring assisted trimetallic transition metal phoshide with in situ generated active si... more Heterostructuring assisted trimetallic transition metal phoshide with in situ generated active sites, exhibits superior catalytic activity towards oxygen evolution reaction in alkaline medium.

ChemCatChem, 2019

Transition metal oxides have attracted attention as promising electrode materials for energy stor... more Transition metal oxides have attracted attention as promising electrode materials for energy storage and conversion devices with high electrochemical activity and stability. In this study, a simple and cost‐effective solvothermal synthesis of rectangular 3D CuCo2O4 hollow tubes have been developed for methanol electro‐oxidation application. Electrochemical analysis shows that CuCo2O4 hollow tubes exhibit superior electrochemical performance in terms of current density and cycling stability, with 75 mA cm−2 and 90 % retention rate after 1000 cycles, respectively. The high electrochemical performances are mainly due to the morphological structure of CuCo2O4 hollow tubes, which possess high surface area and porosity, resulting to a faster electron‐ion transfer, enhanced reactivity and stability. Given that the synthesis of CuCo2O4 hollow tubes involve a facile and cost‐effective technique, the present approach, thus, opens a new era to novel materials for large‐scale processes in diffe...

ChemCatChem, 2019

Finding metal‐free, carbon‐based, highly active, and durable electrocatalyst for oxygen evolution... more Finding metal‐free, carbon‐based, highly active, and durable electrocatalyst for oxygen evolution reaction (OER) is essential for the development of electrochemical energy storage and conversion systems. Herein, we report the synthesis of graphitic carbon nitride (g‐C3N4) nanorods using a hydrothermal method. The transformation of bulk g‐C3N4 (denoted as g‐B‐CN) to g‐C3N4 1D nanorods (denoted as g‐CN) endowed the material with abundant active sites, increased electrochemical active surface area, and enhanced charge transfer. g‐CN exhibited high activity and durability in catalyzing the OER. The optimized g‐CN achieved a current density of 10 mA cm−2 at an overpotential of 316 mV vs. RHE in 1 M KOH, with a Tafel slope of 125 mV dec−1. The high catalytic performance of g‐CN is mainly attributed to the abundantly exposed unique active sites originatingfrom the 1D morphology and the presence of an oxidized pyridinic nitrogen; elucidating the important role of elaborate morphology tailor...

Journal of Industrial and Engineering Chemistry, 2019

Highlights  Low cost and simple fabrication method for the synthesis of CuO is reported.  CuO m... more Highlights  Low cost and simple fabrication method for the synthesis of CuO is reported.  CuO microstructures were successfully electrodeposited on Ni foam.  CuO/Ni@400 showed better activity for electrochemical methanol oxidation and OER.  Stable electrocatalyst after methanol electro-oxidation and OER.

ChemistrySelect, 2019

Designing and synthesis of efficient, highly active with longer stability and earth abundant cata... more Designing and synthesis of efficient, highly active with longer stability and earth abundant catalysts for the oxygen evolution reaction (OER) is urgent need for the electrochemical production of fuels. In this aspect, herein, facile room‐temperature electrodeposited NiCo layered double hydroxide (NiCo‐LDH) is reported as a highly active and stable electrocatalyst for OER in aqueous solution. In alkaline media, as obtained NiCo LDH shows superior electrocatalytic activity towards water oxidation with overpotential of 270 mV at 10 mA/cm2 with low Tafel slope of 61 mV/dec. The 3D NiCo‐LDH network exhibits excellent structural stability for 36 hours in alkaline media. After testing for stability test, the NiCo‐LDH catalyst maintains its hierarchical 3D network with insignificant degradation in the catalytic activity.

Energy, 2018

Tailoring and Exploring the Basicity of Magnesium Oxide Nanostructures in Ionic Liquids for Clais... more Tailoring and Exploring the Basicity of Magnesium Oxide Nanostructures in Ionic Liquids for Claisen-Schmidt Condensation Reaction

Electrochimica Acta, 2018

Herein, a new fabrication method for CNT nanofiber composite (pPC-FP) through non-covalent intera... more Herein, a new fabrication method for CNT nanofiber composite (pPC-FP) through non-covalent interaction between porphyrin monomers with CNTs is reported. This led to the alleviated agglomeration of pristine CNT without acid pre-treatment, producing a highly porous material with high surface area of 444 m 2 /g and narrow pore size distribution for all pPC-FP nanofiber composites. Enhanced performances of pPC-FP3 and pPC-FP5 (CNT nanofiber with porphyrin monomers) were brought about by the enhanced CNT dispersion, hence, better porosity as compared to pPC. Moreover, through the incorporation of porphyrin monomer, M-NeC bond was simultaneously formed and served as a contributor to the excellent capacitive performance of the material, resulting in the highest capacitance of 150 A/cm 2 at 0.25 mAh/cm 2 with 77 A/cm 2 at 2.5 mAh/cm 2. The composites also exhibited stable performance even after cycling at different current densities (0.25e2.5 mAh/cm 2) for 3000 cycles with almost 100% columbic efficiency. Through p-p stacking interaction, the agglomeration was prevented and CNT was aligned along the axis of the polymer which rendered the nanofibers highly porous resulting to a conductive composite material with excellent electrochemical performance.

Journal of Industrial and Engineering Chemistry, 2018

The development of highly efficient, stable and cost-effective electrocatalyst for oxygen evoluti... more The development of highly efficient, stable and cost-effective electrocatalyst for oxygen evolution reaction (OER) is critical. Herein, we report growth of MnCo 2 S 4 flakes on SS-mesh using two-step strategy, and used as an efficient, highly active and stable electrocatalyst for OER under alkaline condition. The free-standing electrocatalyst delivers exceptional stability of 100 h and activity for OER with overpotential of 290 mV at a current density of 10 mA cm À2 in 1 M KOH. The enhanced electrocatalytic performance was supported experimentally by electrochemical impedance spectra and measurement of the electrochemically active surface area. The high electrochemical active surface area and electrical conductivity of MnCo 2 S 4 flakes played an essential role in their high electrocatalytic performance.

Journal of Alloys and Compounds, 2018

Scalable and simple preparation of metal/metal oxide-carbon composite with high specific surface ... more Scalable and simple preparation of metal/metal oxide-carbon composite with high specific surface areas and designated properties are essential for their large scale practical applications. In view of this, we report an ecofriendly deep eutect solvents (DESs) assisted synthesis of Sn/SnO 2 @C hybrid composite. Herein, we have investigated the crucial role of DESs which collectively acts as solvent-precursorreactant system offering an interesting and exciting physicochemical properties and alternative for the conventional solution-based synthesis methods. TEM images reveal that the massive Sn/SnO 2 nanoparticles with average size of 15e20 nm, are uniformly confined in highly layered porous carbon sheets leading to the carbonaceous composite with large surface area of 500 m 2 /g after thermal treatment. It is noteworthy that the excellent electrochemical performance of Sn/SnO 2 @C hybrid composite for supercapacitor electrode material (109.70 mAh/g at 1.42 mA/cm 2 and almost 100% capacitance retention for 5000 cycles) can be attributed to the higher surface area and synergic properties of Sn and SnO 2. Nevertheless, the carbon matrix with a low degree of graphitization can establishes a good electrical contact and also prevents the detachment of nanoparticles during the course of long-term electrochemical reactions. In addition, selection of less toxic component is possible by virtue of compositional versatility of DESs. Thus the use of DESs can bring froth the twin benefits of solvent-precursor-reactant system and cost effective eco-friendly synthesis route which can be applicable for the synthesis of various metal/metal oxide-carbon composites.

Sensors and Actuators B: Chemical, 2018

The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of mo... more The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 m yolk-shelled ZnCo 2 O 4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo 2 O 4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH 3 and NO 2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo 2 O 4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo 2 O 4 microspheres can be further used in other environment monitoring devices.

ACS Sustainable Chemistry & Engineering, 2018

In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reacti... more In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reaction conditions using 1:1 choline chloride-malonic acid was reported. In the presence of DES, the reaction occurred at a lower temperature (500 °C) compared with that of the respective conventional solid-state synthesis of metal oxides and also with the calcination process involving the metal salts, thereby decreasing the overall formation energy. Differential scanning calorimetry revealed a 2-fold decrease in the endo effect of the thermodestruction of DES, which was observed at a low temperature. The structural pathway taken during the phase and morphology formation was investigated by in situ and ex situ X-ray diffraction (XRD) analysis, Raman spectroscopy, and scanning electron microscopy. The in situ XRD results confirmed the presence of high-temperature α-CoV 2 O 6 , which was finally converted to γ-CoV 2 O 6. On account of the metal speciation in DES similar to the bio-template, well-defined octahedral CoV 2 O 6 nanocrystals were obtained, which exhibited a remarkable OER catalytic activity at current density of 10 mA/cm 2 with an overpotential of mere 324 mV, with excellent durability for greater than 24 h. Thus, a designer DES solvent with characteristics of biodegradability, cost-effectiveness, and renewability demonstrates potential for the synthesis of noble-metal-free OER catalysts, which allows the present synthesis route to fit well within the merits of green chemistry.

Dalton transactions (Cambridge, England : 2003), Jan 18, 2017

A new innovative electrode material (Fe-P800) consisting of a metal complex anchored on carbon vi... more A new innovative electrode material (Fe-P800) consisting of a metal complex anchored on carbon via the utilization of iron-porphyrin conjugated microporous polymer (Fe-CMP) was prepared after pyrolyzing at 800 °C. The usage of the polymer with iron-porphyrin repeating units maximized the possible formation of Fe-Nx coordination within the bulk of the sample while the thermal treatment rendered the carbon framework to form a distinct arrangement between metal, nitrogen and carbon with a high surface area of 450 m2 g-1. The formation of the M-N-C bond, confirmed through XPS analysis, established a direct interaction between metal and carbon material. Thus, an indisputable synergistic effect was observed leading to a high capacitance of 182 F g-1 at a current density of 1 A g-1 despite its low metal loading of ∼1%. It also exhibited a highly robust cycling stability of ∼100% capacitance retention even after 5000 cycles (10 A g-1). In this study, a new mechanism was proposed wherein the...

Electrochimica Acta, 2017

Growth of urchin-like ZnCo2O4 microspheres on nickel foam as a binderfree electrode for high-perf... more Growth of urchin-like ZnCo2O4 microspheres on nickel foam as a binderfree electrode for high-performance supercapacitor and methanol electro-oxidation, Electrochimica Actahttp://dx.

New Journal of Chemistry, 2017

Co(OH)2 nanoflakes directly grown on Ni foam using an electrodeposition route exhibit a promising... more Co(OH)2 nanoflakes directly grown on Ni foam using an electrodeposition route exhibit a promising performance for electrocatalytic oxidation of methanol.

Ceramics International, 2017

In this work, we describe the synthesis of hierarchically mesoporous MnCo 2 O 4 microspheres via ... more In this work, we describe the synthesis of hierarchically mesoporous MnCo 2 O 4 microspheres via a urea-assisted co-precipitation method, followed by a post-annealing treatment in air. The stoichiometric amount of urea serves as a self-template to favor the self-assembly of hierarchically well-organized, 3D interconnected precursor carbonate microspheres under optimized reaction conditions. An electrode fabricated from micro/ nano-structured MnCo 2 O 4 delivers an excellent multi-functional electrochemical performance when used in supercapacitors and methanol electro-oxidations. The electrode exhibits a high specific capacitance of 1857 F/g at a 5 mV/s scan rate, and 97% capacitance retention after 5000 cycles. Also, as an electro-catalyst for methanol oxidation, it maintains an optimum current density up to 95 A/g. The superior electrochemical performance might be attributed to its three-dimensional interconnected porous architecture, which offers a rapid ion/ electron transfer, and structural stability. The synthesis method adopted in the present study is simple, controllable, and easy to carry out at a production scale. Furthermore, the superior electrochemical performance of the as-obtained MnCo 2 O 4 microspheres renders them a potential candidate for various energy applications.