Hierarchical 3D ZnIn₂S₄/graphene nano-heterostructures: their <i>in situ</i> fabrication with dual functionality in solar hydrogen production and as anodes for lithium ion batteries

Kale, Sayali B.,Kalubarme, Ramchandra S.,Mahadadalkar, Manjiri A.,Jadhav, Harsharaj S.,Bhirud, Ashwini P.,Ambekar, Jalinder D.,Park, Chan-Jin,Kale, Bharat B. The Royal Society of Chemistry 2015 Physical Chemistry Chemical Physics Vol.17 No.47

<P>Hierarchical 3D ZnIn2S4/graphene (ZnIn2S4/Gr) nano-heterostructures were successfully synthesized using an in-situ hydrothermal method. The dual functionality of these nano-heterostructures i.e. for solar hydrogen production and lithium ion batteries has been demonstrated for the first time. The ZnIn2S4/Gr nano-heterostructures were optimized by varying the concentrations of graphene for utmost hydrogen production. An inspection of the structure shows the existence of layered hexagonal ZnIn2S4 wrapped in graphene. The reduction of graphene oxide (GO) to graphene was confirmed by Raman and XPS analyses. The morphological analysis demonstrated that ultrathin ZnIn2S4 nanopetals are dispersed on graphene sheets. The optical study reveals the extended absorption edge to the visible region due to the presence of graphene and hence is used as a photocatalyst to transform H2S into eco-friendly hydrogen using solar light. The ZnIn2S4/Gr nano-heterostructure that is comprised of graphene and ZnIn2S4 in a weight ratio of 1 : 99 exhibits enhanced photocatalytically stable hydrogen production i.e. B6365 mmole h(-1) under visible light irradiation using just 0.2 g of nano-heterostructure, which is much higher as compared to bare hierarchical 3D ZnIn2(S4). The heightened photocatalytic activity is attributed to the enhanced charge carrier separation due to graphene which acts as an excellent electron collector and transporter. Furthermore, the usage of nano-heterostructures and pristine ZnIn2S4 as anodes in lithium ion batteries confers the charge capacities of 590 and 320 mA h g(-1) after 220 cycles as compared to their initial reversible capacities of 645 and 523 mA h g(-1), respectively. These nano-heterostructures show high reversible capacity, excellent cycling stability, and high-rate capability indicating their potential as promising anode materials for LIBs. The excellent performance is due to the nanostructuring of ZnIn2S4 and the presence of a graphene layer, which works as a channel for the supply of electrons during the charge-discharge process. More significantly, their dual functionality in energy generation and storage is quite unique and commendable.</P>

Confinement of Ag₃PO₄ nanoparticles supported by surface plasmon resonance of Ag in glass: Efficient nanoscale photocatalyst for solar H₂ production from waste H₂S

Patil, S.S.,Patil, D.R.,Apte, S.K.,Kulkarni, M.V.,Ambekar, J.D.,Park, C.J.,Gosavi, S.W.,Kolekar, S.S.,Kale, B.B. Elsevier 2016 Applied Catalysis B Vol.190 No.-

<P>Ag3PO4 is a good photocatalyst but ubiquitously known for its photocorrosion problem during photocatalytic reaction. Therefore, stabilization of Ag3PO4 with retaining its fundamental properties has immense importance. With this motivation, we designed Ag3PO4 glass nanocomposite to resolve the problem of photocorrosion. Moreover, the effect of size quantization on photocatalytic activity has also been demonstrated by growing the cubic Ag3PO4 nanoparticles with size in the range of 3-9 nm in glass matrix via melt and quenching method. The band gap of Ag3PO4 has been tuned (2.56-2.25 eV) in glass matrix with respect to size. Considering the size tunable band gap of Ag3PO4 glass nanocomposite within visible region, it is demonstrated as a photocatalyst for hydrogen (H-2) production from copious hazardous waste H2S. The utmost H-2 production i.e. 3920.4 mu mol h(-1) g(-1) is obtained using 1 gm of Ag3PO4 glass nanocomposite powder. The apparent quantum yield for H-2 production is calculated to be 5.51% for Ag3PO4 glass nanocomposite. Interestingly, presence of plasmonic Ag was also observed in Ag3PO4 glass nanocomposite which contributes for H-2 production through enhanced light absorption, efficient charge separation and improved stability. Recycling study of sample reveals stable H-2 production efficiency and good stability of the photocatalyst. Surprisingly, catalyst can be reused many times and recovery of catalyst is possible just rinsing with distilled water. All these results demonstrate directly the feasibility of designing a new generation photocatalysts. (C) 2016 Published by Elsevier B.V.</P>

Green approach for hierarchical nanostructured Ag-ZnO and their photocatalytic performance under sunlight

Patil, S.S.,Mali, M.G.,Tamboli, M.S.,Patil, D.R.,Kulkarni, M.V.,Yoon, H.,Kim, H.,Al-Deyab, S.S.,Yoon, S.S.,Kolekar, S.S.,Kale, B.B. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.260 No.-

<P>In this study, the synthesis of silver-zinc oxide (Ag-ZnO) nanostructures with a plant-extract-mediated hydrothermal method was investigated. The eco-friendly plant extract Azadirachta indica (Neem) was used as a reducing agent. The X-ray diffraction patterns showed the formation of face-centered cubic (fcc) Ag nanoparticles (NPs) and a wurtzite ZnO structure. An optical study of these nanostructures revealed two absorption edges: one at 393 nm corresponding to ZnO and the other at approximately 440 nm corresponding to Ag. A morphology study showed that hierarchical ZnO nanostructures were decorated with 10-50-nm-diameter Ag NPs. The formation and growth mechanism were also examined. A photoelectrochemical study was performed to investigate the electronic interactions between the ZnO and Ag NPs in the photoanode upon exposure to light. The Ag NPs act as electron acceptors, inhibiting electron-hole recombination. The photocatalytic activity of the Ag-ZnO nanostructures was examined by observing the degradation of aqueous methylene blue (MB) dye under natural sunlight. The apparent rate constant determined for the photocatalytic degradation of MB by the Ag-ZnO nanostructures was 5.9668 x 10(-2) min(-1), which was faster than that of the untreated ZnO nanostructures (2.527 x 10(-2) mm(-1)). This plant-extract-mediated synthetic route could also be applied to the synthesis of other Ag-semiconductor oxide nanostructures. (C) 2015 Elsevier B.V. All rights reserved.</P>

Graphene-wrapped Ag 3 PO 4 /LaCO 3 OH heterostructures for water purification under visible light

Patil, Santosh S.,Mali, Mukund G.,Roy, Animesh,Tamboli, Mohaseen S.,Deonikar, Virendrakumar G.,Patil, Deepak R.,Kulkarni, Milind V.,Al-Deyab, Salem S.,Yoon, Sam S.,Kolekar, Sanjay S.,Kale, Bharat B. Elsevier 2016 Journal of energy chemistry Vol.25 No.5

<P>We demonstrated a unique synthesis approach of graphene (GR)-wrapped Ag3PO4/LaCO3OH (APO/LCO) heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO (2.41 eV) and LCO (4.1 eV). Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO (APO/LCO20/GR) exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min(-1). The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents (APO, LCO, APO/LCO20). The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.</P>

모노클리닉 ZnBiVO4: 수소제조용 신규 광촉매

B.B. Kale,백진욱,문상진,장현주,이철위 한국수소및신에너지학회 2005 한국수소 및 신에너지학회논문집 Vol.16 No.3

Zn, Bi 와 V 금속이온 전구체를 사용하여 모노클리닉 결정구조를 갖는 신규 ZnBiVO4 광촉매를 손쉽게 합성 할 수 있는 방법을 개발하였다. 합성된 ZnBiVO4 광촉매는 XRD 과 FESEM등을 이용하여 미세구조를 분석하였으며, 분석결과 본 삼성분계 금속산화물 반도체 광촉매는 모노클리닉 결정구조를 갖는 것을 알 수 있었다. 저온 수용액방법에 의해 손쉽게 나노 구조를 같는 ZnBiVO4가 제조 되었으며, 그 광촉매의 최소 입자크기는 20-30 nm 이다. ZnBiVO4 광촉매는 UV-visible DRS (diffuse reflectance spectroscopy)로 그 띠간격(band gap)을 측정하였으며, FT-IR을 사용하여 구조 및 물질 상의 순도를 확인 하였다. 그리고 H2S를 광분해하여 수소를 발생하는(122ml/hr․g) 우수한 광촉매 활성을 보여 주었다.

The deformation and fracture behaviors of 316L stainless steels fabricated by spark plasma sintering technique under uniaxial tension

Kale, Amol B.,Bag, Atanu,Hwang, Ji-Hyun,Castle, Elinor G.,Reece, Mike J.,Choi, Shi-Hoon Elsevier 2017 Materials science & engineering. properties, micro Vol.707 No.-

<P><B>Abstract</B></P> <P>In this study, 316L stainless steel (SS) specimens with different relative densities were fabricated using the spark plasma sintering (SPS) technique. These SPS specimens were used to capture the effect of microstructure heterogeneity on deformation and fracture behaviors during uniaxial tension. Microstructure analysis indicated that the SPS specimens consisted of fully sintered and partially sintered regions and contained initial pores which are located at the grain boundaries. Mini-tension tests combined with the digital image correlation (DIC) technique were carried out at room temperature to measure the mechanical properties of the SPS specimens and the evolution of strain heterogeneity on tensile specimens during uniaxial tension. In order to reveal the fracture mechanisms of the SPS specimens, the surfaces of the fractured specimens were analyzed via field emission scanning electron microscope (FE-SEM). The fracture mechanism in the fully sintered region was identified as a ductile fracture by the formation of cup-like dimples, while the fracture mechanism in the partially sintered region was identified as a decohesion of the interface between the powder and the matrix.</P>

Confinement of nano CdS in designated glass: a novel functionality of quantum dot–glass nanosystems in solar hydrogen production

Kale, Bharat B.,Baeg, Jin-Ook,Apte, Sanjay K.,Sonawane, Ravindra S.,Naik, Sonali D.,Patil, Kashinath R. Royal Society of Chemistry 2007 Journal of materials chemistry Vol.17 No.40

<P>The present work is the investigation of our novel approach to designing quantum dot–glass nanosystems by confining nano CdS in designated glass and the first employment of such a quantum dot system in solar hydrogen production. The CdS quantum dots were grown in a special glass matrix, which involved a sequence of steps. The obtained glass was of uniformly bright yellow in color and the bulk glass was pulverized to a fine powder of micron size particles. The glass powder was characterized structurally and morphologically. X-Ray diffraction and electron diffraction patterns reveal a hexagonal crystallite system for the CdS quantum dots. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy and chemical leaching with HCl studies demonstrate that the 2.5 nm size CdS quantum dots distribute homogeneously in a monodispersed form in the glass domain and on the surface with a “partially embedded exposure” configuration. This disposition imparts an excellent photostability against photocorrosion and also a facile catalytic function. Therefore, even a very small amount of CdS quantum dots (0.005 g per gram of glass powder) is able to photodecompose H<SUB>2</SUB>S under visible light (<I>λ</I> ≥ 420 nm) both in alkaline and pure aqueous media and produce solar hydrogen with markedly high quantum yields of 17.5 and 11.4%, respectively at 470 nm. Salient features like reusability after simple washing, corrosionless-stability and remarkable catalytic activity of this quantum dot–glass nanosystem are brought forth by our novel catalyst design and are much acclaimed in large scale solar H<SUB>2</SUB> production.</P> <P>Graphic Abstract</P><P>CdS quantum dots (∼2.5 nm) in a “partially embedded exposure” configuration were grown in a special glass matrix. This nanosystem was employed for the first time for the photocatalytic production of H<SUB>2</SUB> under visible light. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b708269j'> </P>

Perfluorinated polysiloxane hybridized with graphene oxide for corrosion inhibition of AZ31 magnesium alloy

Ikhe, A.B.,Kale, A.B.,Jeong, J.,Reece, M.J.,Choi, S.H.,Pyo, M. Pergamon Press 2016 Corrosion science Vol.109 No.-

Perfluorinated polysiloxane [-(SiR<SUB>1</SUB>R<SUB>2</SUB>-O)<SUB>n</SUB>-, where R<SUB>1</SUB> is -OH and R<SUB>2</SUB> is -CH<SUB>2</SUB>)<SUB>2</SUB>-(CF<SUB>2</SUB>)<SUB>5</SUB>-CF<SUB>3</SUB>], was synthesized from 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) and hybridized with graphene oxide (GO). The composite (PPFS/GO) was applied to AZ31 Mg alloy for corrosion protection in NaCl. Efficient inhibition by PPFS/GO was realized due to a synergistic effect via the remnant hydrophobic-properties of PFOTES and the high surface area of GO. The polymeric nature of PPFS also contributed to the strong adhesion between the coating layer and AZ31, making this work different to most previous reports where the Mg surface was pretreated before coating.

A new layer perovskites Pb₂Ga₂Nb₂O₁₀ and RbPb₂Nb₂O₇: An efficient visible light driven photocatalysts to hydrogen generation

Kanade, K.G.,Baeg, J.O.,Kong, K.j.,Kale, B.B.,Lee, S.M.,Moon, S.J.,Lee, C.W.,Yoon, S. Pergamon Press ; Elsevier Science Ltd 2008 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.33 No.23

We report here the novel approach to synthesis of layer perovskite photocatalysts, Pb<SUB>2</SUB>Ga<SUB>2</SUB>Nb<SUB>2</SUB>O<SUB>10</SUB> and RbPb<SUB>2</SUB>Nb<SUB>2</SUB>O<SUB>7</SUB> using solid state route (SSR) and molten salt synthesis (MSS) method. The reported modified MSS method has advantage over conventional SSR method for uniform particle size, well-defined crystal structure, controlled morphology and stoichiometry vis-a-vis photocatalysis. The structural study was performed using X-ray difractometry (XRD) and computation based on density functional theory (DFT). The simulation study showed that both the compounds belong to the Ruddlesden-Popper phase (A'<SUB>2</SUB>A<SUB>n-1</SUB>B<SUB>n</SUB>O<SUB>3n+1</SUB>; n=2 or 3). The surface morphology of the materials was studied using field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The average particles size of perovskites Pb<SUB>2</SUB>Ga<SUB>2</SUB>Nb<SUB>2</SUB>O<SUB>10</SUB> and RbPb<SUB>2</SUB>Nb<SUB>2</SUB>O<SUB>7</SUB> was in the range 20-40 and 70-90nm respectively. The efficacy of these materials was studied to particle size and morphology as a visible light driven photocatalyst for the hydrogen generation from H<SUB>2</SUB>S. Electronic band structure with DOS has also been performed for both the materials. Being a stable single-phase ternary-layered oxide perovskites and band gap (2.75eV) in visible domain, they may have potential applications in electronic devices as well.

Multiple band gap energy layered electrode for photoelectrochemical cells

Kale, S.S.,Mane, R.S.,Ganesh, T.,Pawar, B.N.,Han, S.H. Elsevier 2009 CURRENT APPLIED PHYSICS Vol.9 No.2

Using wet chemistry, electrode of multiple band gap energy starting from wide titanium dioxide (TiO<SUB>2</SUB>) 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.