Hydrophilic polyaniline nanofibrous architecture using electrosynthesis method for supercapacitor application

D.S. Dhawale,R.R. Salunkhe,V.S. Jamadade,D.P. Dubal,S.M. Pawar,C.D. Lokhande 한국물리학회 2010 Current Applied Physics Vol.10 No.3

An electrosynthesis process of hydrophilic polyaniline nanofiber electrode for electrochemical supercapacitor is described. The TGA–DTA study showed polyaniline thermally stable up to 323 K. Polyaniline nanofibers exhibit amorphous nature as confirmed from XRD study. Smooth interconnected fibers having diameter between 120–125 nm and length typically ranges between 400–500 nm observed from SEM and TEM analysis. Contact angle measurement indicated hydrophilic nature of polyaniline fibers. Optical study revealed the presence of direct band gap with energy 2.52 eV. The Hall effect measurement showed room temperature resistivity ~3 × 10-4 Ω cm and Hall mobility 549.35 cm-2V-1 s-1. The supercapacitive performance of nanofibrous polyaniline film tested in 1 M H2SO4 electrolyte and showed highest specific capacitance of 861 F g-1 at the voltage scan rate of 10 mV/s.

Structural, morphological, compositional, and optical properties of single step electrodeposited Cu₂ZnSnS₄ (CZTS) thin films for solar cell application

Lee, S.G.,Kim, J.,Woo, H.S.,Jo, Y.,Inamdar, A.I.,Pawar, S.M.,Kim, H.S.,Jung, W.,Im, H.S. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.3

We fabricate a Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> (CZTS) absorber layer, by using single step electrodeposition of CZTS precursor, deposited at -1.05 V, followed by high temperature annealing in a sulfur atmosphere. X-ray diffraction pattern indicates that the as-grown sample is amorphous in nature, and polycrystalline CZTS thin films with kesterite crystal structure have been obtained by sulfurization from 450 to 580 <SUP>o</SUP>C. Surface morphologies of the as-grown sample show some voids with agglomerated particles. After sulfurization, the morphologies of the annealed samples become more uniform, and dense. EDAX study reveals that the sulfurized samples are nearly stoichiometric, being Cu-rich and S-deficient in composition. The band gaps of the annealed samples are found to be in the range from 1.9 to 1.5 eV.

The growth mechanism and supercapacitor study of anodically deposited amorphous ruthenium oxide filmss

V.D. Patake,S.M. Pawar,V.R. Shinde,T.P. Gujar,C.D. Lokhande 한국물리학회 2010 Current Applied Physics Vol.10 No.1

In the present study, ruthenium oxide (RuO2) thin films were deposited on the stainless steel (s.s.) substrates by anodic deposition. The nucleation and growth mechanism of electrodeposited RuO2 film has been studied by cyclic voltammetry (CV) and chronoamperometry (CA). The deposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive analysis by X-rays (EDAX) for structural, morphological, and compositional studies. The electrochemical supercapacitor study of ruthenium oxide thin films have been carried out for different film thicknesses in 0.5 M H2SO4 electrolyte. The highest specific capacitance was found to be 1190 F/g for 0.376 mg/㎠ film thickness.

Optical properties in Mn-doped ZnS thin films: Photoluminescence quenching

Inamdar, A.I.,Cho, S.,Jo, Y.,Kim, J.,Han, J.,Pawar, S.M.,Woo, H.,Kalubarme, R.S.,Park, C.,Kim, H.,Im, H. North-Holland 2016 Materials letters Vol.163 No.-

Mn-doped ZnS thin films are synthesized on soda-lime glass substrates using magnetron co-sputtering technique. X-ray diffraction and atomic force microscopy measurements indicate that of the as-obtained films including the highest Mn (~11% relative to the Zn concentration) in the lattice of ZnS are amorphous with a granular morphology. X-ray photoelectron spectroscopy reveals the presence of Zn<SUP>2+</SUP>, Mn<SUP>2+</SUP> and S<SUP>2-</SUP> chemical states in the films. The undoped ZnS film exhibits photoluminescence (PL) peaks at energies around 3.26eV (wavelength ~379nm) and 2.95eV (~420nm), which originate from the interplay between excited electron, defect (sulfur vacancy) states and the valence band. For the Mn-doped ZnS films, the band-to-band emission peak is quenched and shifts toward to higher energies at a rate of 11.7+/-2meV/Mn%. We propose that Mn dopant-mediated structural phases and non-radiative deep traps in ZnS cause the modification in the optical transition.

Bendable RuO₂/graphene thin film for fully flexible supercapacitor electrodes with superior stability

Cho, Sangeun,Kim, Jongmin,Jo, Yongcheol,Ahmed, Abu Talha Aqueel,Chavan, H.S.,Woo, Hyeonseok,Inamdar, A.I.,Gunjakar, J.L.,Pawar, S.M.,Park, Youngsin,Kim, Hyungsang,Im, Hyunsik ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.725 No.-

<P><B>Abstract</B></P> <P>Ruthenium oxide (RuO<SUB>2</SUB>) is fabricated on graphene (Gr)-coated Copper (Cu) foil by using a cathodic electroplating technique for flexible supercapacitor electrode applications. The electrochemical properties of the RuO<SUB>2</SUB>/Gr/Cu electrode are investigated with a conventional three electrode configuration in 0.5 M H<SUB>2</SUB>SO<SUB>4</SUB> electrolyte. The graphene insertion layer plays a key role in improving the structural and electrochemical properties of the RuO<SUB>2</SUB> electrode film under the bent condition. The electrode exhibits a specific capacitance of 1561 F g<SUP>−1</SUP> (0.015 F cm<SUP>−1</SUP>) at a scan rate of 5 mV s<SUP>−1</SUP> and a significantly improved retention of 98% under the bent condition. The flexible RuO<SUB>2</SUB>/Gr/Cu electrode exhibits a high energy density of ∼13 Wh kg<SUP>−1</SUP> at a power density of ∼21 kW kg<SUP>−1</SUP>. The excellent capacitance retention and electrochemical stability of the flexible RuO<SUB>2</SUB>/Gr/Cu electrode are due to the improved mechanical adhesion between the RuO<SUB>2</SUB> and the current collector. This flexible RuO<SUB>2</SUB>/Gr/Cu film could be used as a supercapacitor electrode with a high capacity and long-cycle life for the next-generation flexible electronic applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A binder-free Bendable RuO<SUB>2</SUB> thin film is fabricated on a graphene/Cu substrate using an electroplating method. </LI> <LI> Electrochemical energy storage properties of RuO<SUB>2</SUB> are investigated for supercapacitor applications. </LI> <LI> Excellent capacitance retention and electrochemical stability are obtained. </LI> </UL> </P>

Influence of vacuum annealing on the structural and photoelectrochemical properties of nanocrystalline MoBi₂S₅ thin films

Pawar, N.B.,Mali, S.S.,Kharade, S.D.,Gang, M.G.,Patil, P.S.,Kim, J.H.,Hong, C.K.,Bhosale, P.N. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.3

In the present paper we report structural, optical, morphological and electrical properties of thin films of MoBi<SUB>2</SUB>S<SUB>5</SUB> prepared by facile self organized arrested precipitation technique (APT) from aqueous alkaline bath. X-ray diffraction study on thin films suggests orthorhombic and rhombohedral mixed phase structure. The samples are further annealed under vacuum at 373 and 473 K. The EDS pattern shows minor loss of sulphur upto 473 K. The optical absorption in visible region shows direct allowed transition with band gap variation over 1.2-1.1 eV. Post-heat treated samples exhibit n-type electrical conductivity. SEM images show uniform distribution of spherical grains with diameter ~200 nm for as-synthesized MoBi<SUB>2</SUB>S<SUB>5</SUB> thin film. The grain size increases with annealing temperature and morphology becomes more compact due to crystallization of thin film. The surface roughness deduced from AFM, was in the range of 1.29-1.92 nm. The MoBi<SUB>2</SUB>S<SUB>5</SUB> thin films are employed for the fabrication of photoelectrochemical solar cells as all the samples exhibit strong absorption in visible to near IR region. Due to vacuum annealing it gives a significant enhancement of power conversion efficiency (η) upto 0.14% as compared to as-synthesized MoBi<SUB>2</SUB>S<SUB>5</SUB> thin film.

Nanoporous CuCo₂O₄ nanosheets as a highly efficient bifunctional electrode for supercapacitors and water oxidation catalysis

Pawar, Sambhaji M.,Pawar, Bharati S.,Babar, Pravin T.,Ahmed, Abu Talha Aqueel,Chavan, Harish S.,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Hou, Bo,Inamdar, Akbar I.,Cha, SeungNam,Kim, Jin Hyeok,Kim, Tae Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.470 No.-

<P><B>Abstract</B></P> <P>Efficient and low‐cost multifunctional electrodes play a key role in improving the performance of energy conversion and storage devices. In this study, ultrathin nanoporous CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets are synthesized on a nickel foam substrate using electrodeposition followed by air annealing. The CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet electrode exhibits a high specific capacitance of 1473 F g<SUP>─1</SUP> at 1 A g<SUP>─1</SUP> with a capacity retention of ∼93% after 5000 cycles in 3 M KOH solution. It also works well as an efficient oxygen evolution reaction electrocatalyst, demonstrating an overpotential of 260 mV at 20 mA cm<SUP>─2</SUP> with a Tafel slope of ∼64 mV dec<SUP>─1</SUP>. in 1 M KOH solution, which is the lowest reported among other copper-cobalt based transition metal oxide catalysts. The catalyst is very stable at >20 mA cm<SUP>─2</SUP> for more than 25 h. The superior electrochemical performance of the CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet electrode is due to the synergetic effect of the direct growth of 2D nanosheet structure and a large electrochemically active surface area associated with nanopores on the CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ultrathin nanoporous CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets electrode synthesized by electrodeposition. </LI> <LI> High specific capacitance and good cycling stability were obtained. </LI> <LI> Highly efficient OER electrocatalyst with an overpotential of 260 mV at 20 mA/cm<SUP>2</SUP>. </LI> <LI> Excellent long-term electrochemical durability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films

Pawar, S.M.,Pawar, B.S.,Kim, J.H.,Joo, O.S.,Lokhande, C.D. Elsevier 2011 Current Applied Physics Vol.11 No.2

Presently nanocrystalline materials have opened a new chapter in the field of electronic applications, since material properties could be changed by changing the crystallite size and/or thickness of the film. The synthesis of nanocrystalline metal chalcogenide and metal oxide thin films by chemical bath deposition (CBD) method is currently attracting considerable attention as it is relatively inexpensive, simple and convenient for large area deposition. Using CBD and modified CBD (which is also known as successive ionic layer adsorption and reaction, SILAR) methods, a large number of thin films have been deposited. This review is on the status of synthesizing thin films of metal chalcogenide and metal oxides by CBD and SILAR. Properties and applications of the thin films are also summarized.

Fabrication of Fe:CdSe solar rechargeable (semiconductor–septum) storage cells

Pawar, S.M.,Moholkar, A.V.,Rajpure, K.Y.,Kim, J.H.,Lokhande, C.D.,Bhosale, C.H. Elsevier 2009 Current Applied Physics Vol.9 No.5

<P><B>Abstract</B></P><P>The Fe:CdSe thin films have been electrodeposited potentiostatically onto the stainless steel substrates, from non-aqueous bath containing (CH<SUB>3</SUB>COO)<SUB>2</SUB>·Cd·2H<SUB>2</SUB>O, SeO<SUB>2</SUB> and FeCl<SUB>3</SUB>. The solar rechargeable (semiconductor–septum) storage cell is fabricated with the configuration C|1M polysulphide|<I>n</I>-Fe:CdSe|stainless steel||1M FeCl<SUB>3</SUB> or 1M K<SUB>4</SUB>Fe(CN)<SUB>6</SUB>|C. The charging and discharging modes are studied and discussed. The comparison of FeCl<SUB>3</SUB> and K<SUB>4</SUB>Fe(CN)<SUB>6</SUB> based solar rechargeable storage cells, showed that FeCl<SUB>3</SUB> based storage cell is superior than that of K<SUB>4</SUB>Fe(CN)<SUB>6</SUB> based electrolyte because relatively charging time is minimum and discharging time is maximum. Thus it is concluded that the storage cell works not only as a generator but also as the storage of electricity.</P>

Fabrication of Fe:CdSe solar rechargeable (semiconductor–septum) storage cells

S.M. Pawar,A.V. Moholkar,김진혁,K.Y. Rajpure,C.D. Lokhande,C.H. Bhosale 한국물리학회 2009 Current Applied Physics Vol.9 No.5

The Fe:CdSe thin films have been electrodeposited potentiostatically onto the stainless steel substrates, from non-aqueous bath containing (CH3COO)2 Cd 2H2O, SeO2 and FeCl3. The solar rechargeable (semiconductor-septum) storage cell is fabricated with the configuration C|1 M polysulphide|n-Fe:CdSe|stainless steel||1 M FeCl3 or 1 M K4Fe(CN)6|C. The charging and discharging modes are studied and discussed. The comparison of FeCl3 and K4Fe(CN)6 based solar rechargeable storage cells, showed that FeCl3 based storage cell is superior than that of K4Fe(CN)6 based electrolyte because relatively charging time is minimum and discharging time is maximum. Thus it is concluded that the storage cell works not only as a generator but also as the storage of electricity.