Transition of hexagonal to square sheets of Co3O4 in a triple heterostructure of Co3O4/MnO2/GO for high performance supercapacitor electrode

Sachin A. Pawar,Dipali S. Patil,신재철 한국물리학회 2019 Current Applied Physics Vol.19 No.7

Cobalt oxide and manganese oxides are promising electrode materials amongst the transition metal oxides (TMOs) for pseudocapacitors. The lack of reversibility and deterioration of capacitance at higher current densities is major flaw in Co3O4 as an electrode for supercapacitor while MnO2 suffers from low electrical conductivity and poor cycling stability. It is inevitable to bridge the performance gap between these two TMOs to obtain a high performance supercapacitor based on environmental benign and earth abundant materials. Herein, we fabricated a hybrid triple heterostructure high-performing supercapacitor based on hexagonal sheets of Co3O4, MnO2 nanowires and graphene oxide (GO) to form a composite structure of Co3O4/MnO2/GO by all hydrothermal synthesis route. The Co3O4 square sheets serves as an excellent backbone with good mechanical adhesion with the current collector providing a rapid electronic transfer channel while the integrated nanostructure of MnO2 NW/GO permits more electrolyte ions to penetrate capably into the hybrid structure and allows effective utilization of more active surface areas. A triple heterostructured device exhibits a high areal capacitance of 3087 mF cm−2 at 10 mV s−1 scan rate along with the exceptional rate capability and cycling stability having capacitance retention of ∼170% after 5000 charge/discharge cycles. The TMOs based pseudocapacitor with the conducting scaffolds anchoring based on graphene derivatives like this will pave an encouraging alternatives for next generation energy storage devices.

Electrochemical battery-type supercapacitor based on chemosynthesized Cu₂SAg₂S composite electrode

Pawar, Sachin A.,Patil, Dipali S.,Shin, Jae Cheol Elsevier 2018 ELECTROCHIMICA ACTA Vol.259 No.-

<P><B>Abstract</B></P> <P>Metal sulfide-based electrochemical supercapacitors are widely attracted owing to their high electrical conductivity and excellent redox properties. Moreover, the fabrication of high performance supercapacitors based on simple and cost effective chemical routes is in strong demand. In this study, a facile and low cost, successive ionic layer adsorption and reaction (SILAR) technique is used to form a Cu<SUB>2</SUB>SAg<SUB>2</SUB>S composite electrode on nickel foam in a common sulfur source beaker for both copper and silver with less time and material consumption. The electrodes exhibits a high specific capacity of 772 Cg<SUP>−1</SUP> at a scan rate of 10 mVs<SUP>−1</SUP> compared to pristine Cu<SUB>2</SUB>S and Ag<SUB>2</SUB>S and shows excellent cycling stability with a capacity retention of 89% after 2000 CV cycles. This is attributed to the highly conductive and reactive Ag<SUB>2</SUB>S layer, which simplifies the diffusion of electrolyte ions to access active Cu<SUB>2</SUB>S materials and facilitates rapid electron transport to achieve high-performance battery-type supercapacitors. This study provides a simple and cost-effective approach to the fabrication of high-performance battery-type supercapacitors based on highly conductive and earth-abundant, copper-based composite metal sulfide electrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu<SUB>2</SUB>SAg<SUB>2</SUB>S composite electrode is synthesized by SILAR technique. </LI> <LI> A common sulfur source beaker is kept for both copper and silver in SILAR. </LI> <LI> Cu<SUB>2</SUB>SAg<SUB>2</SUB>S exhibited a specific capacity of 772 Cg<SUP>−1</SUP> at a scan rate of 10 mVs<SUP>−1</SUP>. </LI> <LI> An excellent cycling stability with a capacity retention of 89% is observed. </LI> <LI> Efficient supercapacitor fabrication by simple and cost effective chemical route. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A facile and low cost, successive ionic layer adsorption and reaction (SILAR) technique was used to form a Cu<SUB>2</SUB>SAg<SUB>2</SUB>S composite electrode on nickel foam in a common sulfur source beaker for both copper and silver with less time and material consumption.</P> <P>[DISPLAY OMISSION]</P>

Investigations on silver/polyaniline electrodes for electrochemical supercapacitors

Patil, Dipali S.,Shaikh, J. S.,Pawar, S. A.,Devan, R. S.,Ma, Y. R.,Moholkar, A. V.,Kim, J. H.,Kalubarme, R. S.,Park, C. J.,Patil, P. S. The Royal Society of Chemistry 2012 Physical chemistry chemical physics Vol.14 No.34

<P>Polyaniline (PANI) and silver doped polyaniline (Ag/PANI) thin films were deposited on stainless steel substrates by a dip coating technique. To study the effect of doping concentration of Ag on the specific capacitance of PANI the concentration of Ag was varied from 0.3 to 1.2 weight percent. Fourier transform-infrared and Fourier transform-Raman spectroscopy, and energy dispersion X-ray techniques were used for the phase identification and determination of the doping content in the PANI films, respectively. The surface morphology of the films was examined by Field Emission Scanning Electron Microscopy, which revealed a nanofiber like structure for PANI and nanofibers with bright spots of Ag particles for the Ag/PANI films. There was decrease in the room temperature electrical resistivity of the Ag/PANI films of the order of 10<SUP>2</SUP> with increasing Ag concentration. The supercapacitive behavior of the electrodes was tested in a three electrode system using 1.0 M H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte. The specific capacitance increased from 285 F g<SUP>−1</SUP> (for PANI) to 512 F g<SUP>−1</SUP> for Ag/PANI at 0.9 weight percent doping of Ag, owing to the synergic effect of PANI and silver nanoparticles. This work demonstrates a simple strategy of improving the specific capacitance of polymer electrodes and may also be easily adopted for other dopants.</P> <P>Graphic Abstract</P><P>The presence of Ag nanoparticles on PANI nanofibers provides a least resistance path to electron transportation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cp41757j'> </P>

Quantum dot sensitized solar cell based on TiO₂/CdS/Ag₂S heterostructure

Pawar, Sachin A.,Patil, Dipali S.,Kim, Jin Hyeok,Patil, Pramod S.,Shin, Jae Cheol Elsevier 2017 Optical Materials Vol.66 No.-

<P><B>Abstract</B></P> <P>Quantum dot sensitized solar cell (QDSSC) is fabricated based on a stepwise band structure of TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S to improve the photoconversion efficiency of TiO<SUB>2</SUB>/CdS system by incorporating a low band gap Ag<SUB>2</SUB>S QDs. Vertically aligned TiO<SUB>2</SUB> nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS and Ag<SUB>2</SUB>S QDs over TiO<SUB>2</SUB> nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), Optical, solar cell and electrochemical performances. The results designate that the QDs of CdS and Ag<SUB>2</SUB>S have efficiently covered exterior surfaces of TiO<SUB>2</SUB> nanorods assembly. A cautious evaluation between TiO<SUB>2</SUB>/CdS and TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S sensitized cells tells that CdS and Ag<SUB>2</SUB>S synergetically helps to enhance the light harvesting ability. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 1.87%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 7.03 mA cm<SUP>−2</SUP> which is four fold higher than that of a TiO<SUB>2</SUB>/CdS system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> QDSSC fabrication using 1D TiO<SUB>2</SUB> nanostructures. </LI> <LI> High surface area for QDs loading. </LI> <LI> Strong absorption in the visible regime for TiO<SUB>2</SUB>/CdS/Ag<SUB>2</SUB>S. </LI> <LI> The QDSSC show improved photocurrents. </LI> <LI> High power conversion efficiency of 1.87%. </LI> </UL> </P>

Silver decorated PEDOT:PSS wrapped MnO2 nanowires for electrochemical supercapacitor applications

Dipali S. Patil,Sachin A. Pawar,신재철 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.62 No.-

This paper reports the facile preparation of silver (Ag)-decorated, PEDOT:PSS-wrapped MnO2 nanowire ternary electrode materials for supercapacitor applications. Surface morphology of Ag–PEDOT:PSS–MnO2 material revealed the presence of Ag nanoparticles onto PEDOT:PSS wrapped MnO2 nanowires. This reduces the charge transfer resistance and improves charge transportation between the current collector and active material. The Ag–PEDOT:PSS–MnO2 electrode exhibited enhanced specific capacitance (838 Fg−1), energy density (0.486 kWh kg−1), and capacitance retention (86.8%). In addition, Ag–PEDOT:PSS–MnO2-based symmetric supercapacitor device exhibited ideal capacitive behavior. This study revealed a facile way to improve the electrochemical activity of MnO2 that can also be adopted for other metal oxides.

Cu2S-Ag2S composite electrode on Ni foam for high-performance electrochemical supercapacitors

Sachin A. Pawar,Dipali S. Patil,Jae Cheol Shin 한국진공학회 2017 한국진공학회 학술발표회초록집 Vol.2017 No.2

ZnCo@NiCo-layered double hydroxide nanoarchitecture on 3D graphene scaffold for efficient supercapacitor

Dipali S. Patil,Sachin A. Pawar,Jae Cheol Shin 한국진공학회 2019 한국진공학회 학술발표회초록집 Vol.2019 No.2

MnO₂ nanowires/PEDOT-PSS composites for electrochemical supercapacitor

Dipali S. Patil,Sachin A. Pawar,Jae Cheol Shin 한국진공학회 2017 한국진공학회 학술발표회초록집 Vol.2017 No.2

Core-shell structure of Co₃O₄@CdS for high performance electrochemical supercapacitor

Patil, Dipali S.,Pawar, Sachin A.,Shin, Jae Cheol Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.335 No.-

<P><B>Abstract</B></P> <P>Core-shell nanostructures of Co<SUB>3</SUB>O<SUB>4</SUB>@CdS were synthesized on nickel foam using a facile, economical, scalable, and one pot hydrothermal method and a successive ionic layer adsorption and reaction (SILAR) method. The synergistic effects arising due to the hexagonal Co<SUB>3</SUB>O<SUB>4</SUB> sheets and CdS nanostructures were assessed for potential electrochemical energy storage applications. The effects of the CdS SILAR coating cycles were examined by varying the number of cycles from 2 to 10. The Co<SUB>3</SUB>O<SUB>4</SUB>@CdS core-shell electrode exhibited a high specific capacitance of 1539 Fg<SUP>−1</SUP> (1385 Cg<SUP>−1</SUP>) and 1322 Fg<SUP>−1</SUP> (1189 Cg<SUP>−1</SUP>) at 10 mVs<SUP>−1</SUP> and 30 mA, respectively, with 98.5% capacitance retention after 2000 cycles. In addition, the Co<SUB>3</SUB>O<SUB>4</SUB>@CdS core shell nanostructure-based symmetric supercapacitor displayed excellent capacitive characteristics with a specific capacitance of 360 Fg<SUP>−1</SUP> (288 Cg<SUP>−1</SUP>) and 99 Fg<SUP>−1</SUP> (79 Cg<SUP>−1</SUP>) at 10 mVs<SUP>−1</SUP> and 10 mA, respectively, and 92% capacitance retention after 2000 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CdS coated Co<SUB>3</SUB>O<SUB>4</SUB> hexagonal sheets on Ni foam was prepared by chemical route. </LI> <LI> The uniform shell (CdS) layer acts as conductive layer. </LI> <LI> The Co<SUB>3</SUB>O<SUB>4</SUB>@CdS based symmetric device showed a specific capacitance of 390 Fg<SUP>−1</SUP>. </LI> <LI> The positive synergistic effect of Co<SUB>3</SUB>O<SUB>4</SUB> and CdS is observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A schematic illustration of synthesis of Co<SUB>3</SUB>O<SUB>4</SUB> hexagonal sheets and CdS nanoparticle-decorated Co<SUB>3</SUB>O<SUB>4</SUB> hexagonal sheets on Ni-foam.</P> <P>[DISPLAY OMISSION]</P>

Alteration of Ag nanowires to Ag/Ag₂S nanowires@CdS core-shell architectures for electrochemical supercapacitors

Patil, Dipali S.,Pawar, Sachin A.,Shin, Jae Cheol Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.768 No.-

<P><B>Abstract</B></P> <P>Silver nanowire@cadmium sulfide (AgNW@CdS) core-shell nanostructured electrodes were synthesized in two steps. Initially, a layer of AgNWs was coated onto Ni foam by drop casting. CdS was then deposited onto the pre-coated Ni foam by a successive ionic layer adsorption and reaction (SILAR) method. This process converted the Ag nanowires to Ag<SUB>2</SUB>S, which was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The effects of the CdS layer thickness on AgNWs on the electrochemical properties of the nanostructure were examined by varying the number of SILAR cycles. The resulting AgNWs@CdS electrode exhibited a high areal capacitance of approximately 2662 mFcm<SUP>−2</SUP> at 10 mVs<SUP>−1</SUP> and 810 mFcm<SUP>−2</SUP> at 45 mA applied current.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CdS coated Ag nanowires on Ni foam was prepared by chemical route. </LI> <LI> The Ag nanowires convert into Ag<SUB>2</SUB>S during the deposition of CdS. </LI> <LI> The AgNW@CdS electrode showed a high areal capacitance of 2662 mFcm<SUP>−2</SUP>. </LI> <LI> The positive synergistic effect of Ag nanowires and CdS is observed. </LI> </UL> </P>