Annealing temperature dependent catalytic water oxidation activity of iron oxyhydroxide thin films

Babar, P.T.,Pawar, B.S.,Lokhande, A.C.,Gang, M.G.,Jang, J.S.,Suryawanshi, M.P.,Pawar, S.M.,Kim, Jin Hyeok Elsevier 2017 Journal of energy chemistry Vol.26 No.4

<P>Nanostructured iron oxyhydroxide (FeOOH) thin films have been synthesized using an electrodeposition method on a nickel foam (NF) substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and linear sweep voltammetry (LSV) to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous FeOOH thin film is converted into a polycrystalline Fe2O3 with hematite crystal structure at a high temperature. The FeOOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction (OER) in an alkaline 1 M KOH electrolyte. The film annealed at 200 degrees C shows high catalytic activity with an onset overpotential of 240 mV with a smaller Tafel slope of 48 mV/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 mA/cm(2) and shows good stability in the 1 M KOH electrolyte solution. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.</P>

Facile electrodeposition of high-density CuCo₂O₄ nanosheets as a high-performance Li-ion battery anode material

Pawar, S.M.,Pawar, B.S.,Hou, Bo,Ahmed, A.T.A.,Chavan, H.S.,Jo, Yongcheol,Cho, Sangeun,Kim, Jongmin,Seo, Jiwoo,Cha, SeungNam,Inamdar, A.I.,Kim, Hyungsang,Im, Hyunsik Elsevier 2019 Journal of industrial and engineering chemistry Vol.69 No.-

<P><B>Abstract</B></P> <P>High-density CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets are grown on Ni foam using electrodeposition followed by air annealing for a Li-ion battery anode. The anode exhibits a high discharge capacity of 1244mAh/g at 0.1A/g (82% coulombic efficiency) and excellent high-rate performance with 95% capacity retention (1100mAh/g after 200 cycles at 1A/g). The outstanding battery performance of the CuCo<SUB>2</SUB>O<SUB>4</SUB> anode is attributed to its binder-free direct contact to the current collector and high-density nanosheet morphology. The present experimental findings demonstrate that the electrodeposited binder-free CuCo<SUB>2</SUB>O<SUB>4</SUB> material may serve as a safe, low-cost, long-cycle life anode for Li-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of high-density CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets via electrodeposition method. </LI> <LI> CuCo<SUB>2</SUB>O<SUB>4</SUB> nanosheet electrode exhibits a high discharge capacity of 1244mAh/g at 0.1A/g. </LI> <LI> Excellent rate capability and stability with 95% capacity retention after 200 cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of Cu₂ZnSnS₄ (CZTS) absorber by rapid thermal processing (RTP) sulfurization of stacked metallic precursor films for solar cell applications

Pawar, S.M.,Inamdar, A.I.,Pawar, B.S.,Gurav, K.V.,Shin, S.W.,Yanjun, Xiao,Kolekar, S.S.,Lee, Jung-Ho,Kim, Jin Hyeok,Im, Hyunsik Elsevier 2014 Materials Letters Vol.118 No.-

<P><B>Abstract</B></P> <P>Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> (CZTS) absorbers have been grown on Mo-coated glass substrates by the rapid thermal processing (RTP) sulfurization of stacked metallic precursor (CZT) films at different annealing temperatures ranging from 500 to 580°C for 5min in sulfur atmosphere. The effects of sulfurization temperature on the structural, morphological, chemical, and optical properties of the CZTS absorbers have been investigated. XRD and Raman studies reveal that the as-deposited stacked metallic precursor films consist of metal elements such as Zn, Sn and binary alloys such as Cu<SUB>6</SUB>Sn<SUB>5</SUB>, Cu<SUB>3</SUB>Sn and CuZn. The sulfurized CZTS absorber films have single phase polycrystalline kesterite crystal structure with dense morphology. At 580°C, the CZT metallic precursor film is fully sulfurized with Zn-rich and Sn-poor composition, and its bandgap energy is found to be 1.50eV. The solar cell fabricated with the CZTS absorber grown at an optimized sulfurization temperature of 580°C shows a conversion efficiency of ~5% for a 0.44cm<SUP>2</SUP> area with <I>V</I> <SUB> <I>oc</I> </SUB>=561mV, <I>J</I> <SUB> <I>sc</I> </SUB>=18.4mA/cm<SUP>2</SUP>, and <I>FF</I>=48.2.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single phase Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> is synthesized by rapid thermal processing sulfurization. </LI> <LI> Higher annealing temperature improves the crystallinity of Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> absorber. </LI> <LI> Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> absorber is fully sulfurized at 580°C. </LI> <LI> A solar cell with a ~5% conversion efficiency is demonstrated. </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.

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

N.B. Pawar,S.S. Mali,S.D. Kharade,M.G. Gang,P.S. Patil,김진혁,C.K. Hong,P.N. Bhosale 한국물리학회 2014 Current Applied Physics Vol.14 No.3

In the present paper we report structural, optical, morphological and electrical properties of thin films of MoBi2S5 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 1.2e1.1 eV. Post-heat treated samples exhibit n-type electrical conductivity. SEM images show uniform distribution of spherical grains with diameter w200 nm for as-synthesized MoBi2S5 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 1.29e1.92 nm. The MoBi2S5 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 (h) upto 0.14% as compared to as-synthesized MoBi2S5 thin film.

Facile electrodeposition of high-density CuCo2O4 nanosheets as a high-performance Li-ion battery anode material

S.M. Pawar,B.S. Pawar,Bo Hou,A.T.A. Ahmed,H.S. Chavan,조용철,조상근,김종민,서지우,차승남,A. I. Inamdar,김형상,임현식 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

High-density CuCo2O4 nanosheets are grown on Ni foam using electrodeposition followed by airannealing for a Li-ion battery anode. The anode exhibits a high discharge capacity of 1244 mAh/g at 0.1 A/g (82% coulombic efficiency) and excellent high-rate performance with 95% capacity retention(1100 mAh/g after 200 cycles at 1 A/g). The outstanding battery performance of the CuCo2O4 anode isattributed to its binder-free direct contact to the current collector and high-density nanosheetmorphology. The present experimentalfindings demonstrate that the electrodeposited binder-freeCuCo2O4 material may serve as a safe, low-cost, long-cycle life anode for Li-ion batteries.

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.

Multiple band gap energy layered electrode for photoelectrochemical cells

S.S. Kale,Rajaram S. Mane,T. Ganesh,B.N. Pawar,한성환 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Using wet chemistry, electrode of multiple band gap energy starting from wide titanium dioxide (TiO2) to narrow range cadmium selenide (CdSe) is synthesized. Complete utilization of solar spectrum by initializing the film of wide band gap energy (absorbs high energy photons) permitting to narrow band gap films (absorbs low energy photons), is explored in the manuscript. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectrophotometer techniques were used for the structural, surface morphological and optical studies. The role of every layer of descending band gap energy on the performance of photoelectrochemical cells is demonstrated. The three layered electrode exhibits a good absorbance followed by photoresponse as compared to the bilayers. Using wet chemistry, electrode of multiple band gap energy starting from wide titanium dioxide (TiO2) to narrow range cadmium selenide (CdSe) is synthesized. Complete utilization of solar spectrum by initializing the film of wide band gap energy (absorbs high energy photons) permitting to narrow band gap films (absorbs low energy photons), is explored in the manuscript. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectrophotometer techniques were used for the structural, surface morphological and optical studies. The role of every layer of descending band gap energy on the performance of photoelectrochemical cells is demonstrated. The three layered electrode exhibits a good absorbance followed by photoresponse as compared to the bilayers.

Thermally oxidized porous NiO as an efficient oxygen evolution reaction (OER) electrocatalyst for electrochemical water splitting application

Babar, P.T.,Lokhande, A.C.,Gang, M.G.,Pawar, B.S.,Pawar, S.M.,Kim, Jin Hyeok Elsevier 2018 Journal of industrial and engineering chemistry Vol.60 No.-

<P><B>Abstract</B></P> <P>Low-cost and competent electrocatalysts play a key role in an electrocatalytic water oxidation reaction. Herein, we report that readily available bare nickel foam (NF) can be used as conductive substrate and precursor to grow a porous nickel oxide (NiO) using a simple and scalable thermal oxidation method. The obtained NiO supported on NF is used as binder-free electrocatalyst for the oxygen evolution reaction (OER) and its electrochemical properties are evaluated by linear sweep voltammetry (LSV) in 1M KOH. The porous NiO thin film acts as an efficient electrocatalyst for the OER and achieves a catalytic current density of 10mAcm<SUP>−2</SUP> at an overpotential of 310mV with a smaller Tafel slope of 54mVdec<SUP>−1</SUP>. The electrode also shows good durability over 24h with negligible degradation. This durable and high-performance electrocatalyst can be a competitor to electrocatalysts that consist of costly elements and, require advanced synthesis; the NiO electrocatalyst shows progress towards the replacement of noble metal-based electrocatalysts for the OER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porous NiO has been synthesized by a simple thermal oxidation method. </LI> <LI> Thermally oxidized NiO show significantly enhanced OER activity. </LI> <LI> It is promising for fabrication of low-cost and robust OER electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of different annealing environments on the solar cell performance of CdSe pebbles

Pawar, S.A.,Patil, D.S.,Suryawanshi, M.P.,Ghorpade, U.V.,Lokhande, A.C.,Park, J.Y.,Chalapathy, R.B.V.,Shin, J.C.,Patil, P.S.,Kim, J.H. Elsevier Science 2016 Acta materialia Vol.108 No.-

<P>Cadmium selenide pebbles have been synthesized by a simple and cost-effective chemical bath deposition method. In order to study the effect of different annealing environments, the CdSe thin films were annealed in air, nitrogen, argon and in a vacuum at 300 degrees C for 1 h. The optical, structural, compositional, and morphological properties of the films were then analyzed using UV-vis spectrophotometry, photoluminescence, X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. XRD patterns revealed the formation of amorphous CdSe thin films. Annealing entails a change in crystal structure, from amorphous to hexagonal. The chemical composition and valence states of the constituent elements were analyzed by XPS. FESEM images showed the formation of CdSe pebbles in all the samples with voids between the pebbles, but the samples annealed in a vacuum had fewer voids than did other samples. Under AM 1.5G illumination, the photoanodes had an improved power conversion efficiency of 1.44% using an aqueous polysulfide electrolyte with a short-circuit photocurrent density of 11.3 mA cm(-2) when CdSe pebbles were annealed in a vacuum. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</P>