Towards environmentally benign approaches for the synthesis of CZTSSe nanocrystals by a hot injection method: a status review

Ghorpade, Uma,Suryawanshi, Mahesh,Shin, Seung Wook,Gurav, Kishor,Patil, Pramod,Pawar, Sambhaji,Hong, Chang Woo,Kim, Jin Hyeok,Kolekar, Sanjay The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.77

<P>With the earth's abundance of kesterite, recent progress in chalcogenide based Cu<SUB>2</SUB>ZnSn(S<SUB><I>x</I></SUB>,Se<SUB>1−<I>x</I></SUB>)<SUB>4</SUB> (CZTSSe) thin films has drawn prime attention in thin film solar cells (TFSCs) research and development. This review is focused on the current developments in the synthesis of CZTS nanocrystals (NCs) using a hot injection (HI) technique and provides comprehensive discussions on the current status of CZTSSe TFSCs. This article begins with a description of the advantages of nanoparticulate based thin films, and then introduces the basics of this technique and the corresponding growth mechanism is also discussed. A brief overview further addresses a series of investigations on the developments in the HI based CZTSSe NCs using different solvents in terms of their high toxicity to environmentally benign materials. A variety of recipes and techniques for the NCs ink formulation and thereby the preparation of absorber layers using NC inks are outlined, respectively. The deposition of precursor thin films, post-deposition processes such as sulfurization or selenization treatments and the fabrication of CZTSSe NCs based solar cells and their performances are discussed. Finally, we discussed concluding remarks and the perspectives for further developments in the existing research on CZTSSe based nanoparticulate (NP) TFSCs towards future green technology.</P> <P>Graphic Abstract</P><P>With the earth's abundance of kesterite, recent progress in chalcogenide based Cu<SUB>2</SUB>ZnSn(S<SUB><I>x</I></SUB>,Se<SUB>1−<I>x</I></SUB>)<SUB>4</SUB> (CZTSSe) thin films has drawn prime attention in thin film solar cell (TFSC) research and development. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc03176h'> </P>

New and effective multi-element α-hematite systems for reduction of trichloroethylene

Ghorpade, Praveen,Kim, Jung-Hwan,Choi, Won-Ho,Park, Joo-Yang Informa UK (Taylor Francis) 2014 Environmental Technology Vol.35 No.1

1P-61 Stereoregular poly(acrylonitrile-co-itaconic acid) for improved thermal oxidative stabilization behavior and enhanced carbon properties

( Ghorpade Ravindra ),조동원,홍성철 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.0

Effect of different types of calcium sulfate on the reactivity of cement/Fe(II) system in dechlorination of trichloroethylene

Ghorpade, Praveen A.,Ha, Min-Gyu,Park, Joo-Yang Balaban Publishers 2015 Desalination and Water Treatment Vol. No.

<P> Several studies have been carried out to find out the reactive species in cement/Fe(II) system for the treatment of ground water contaminated with a number of chlorinated organic pollutants such as trichloroethylene (TCE). The previous studies suggest that cement hydration minerals associated with sulfate (SO<SUP>2-</SUP><SUB>4</SUB> ) could be one of the reactive species responsible for dechlorination reaction. Calcium sulfate which is a primary source of sulfate in cement has not been studied in detail. Present study deals with the effect of different types of calcium sulfate on the reactivity of cement/Fe(II) system in dechlorination of TCE. To evaluate the effect of different types of calcium sulfate on reactivity of cement/Fe(II) system, different types of calcium sulfate were mixed with clinker powder to get three different types of cements. TCE reduction experiments were carried out in the presence of Fe(II) using these cements. The results showed that cement with anhydrate and hemihydrate forms of calcium sulfate showed improved TCE reduction kinetics compared to cement with calcium sulfate dihydrate. Different analytical tools such as thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy were used to differentiate between the types of calcium sulfate and understand the minerals generated at the end of TCE reduction experiments. Further studies revealed that the dissolution behavior of calcium sulfate in individual cement was different and had an influence on the formation of ettringite, which was suspected as a reactive mineral. </P>

Eutectic solvent-mediated selective synthesis of Cu-Sb-S-based nanocrystals: combined experimental and theoretical studies toward highly efficient water splitting

Ghorpade, Uma V.,Suryawanshi, Mahesh P.,Shin, Seung Wook,Wang, Xiaoming,Jo, Eunae,Bae, Hyojung,Park, KuSung,Ha, Jun-Seok,Kolekar, Sanjay S.,Kim, Jin Hyeok The Royal Society of Chemistry 2018 Journal of materials chemistry. A, Materials for e Vol.6 No.40

<P>Recently, emerging Cu-Sb-S-based compounds have been identified as an attractive candidate for photovoltaic (PV) applications because of their high natural abundance, eco-friendly features and typical phase-dependent characteristics. Herein, a simple eutectic solvent-mediated (choline chloride/ethylene glycol) synthetic approach for newly debuted Cu-Sb-S-based nanocrystals (NCs) with phase-selective properties is presented. This combination of material and preparation method may promote the exchange of carriers by avoiding a steric hindrance for a facile charge transport encountered in NCs prepared using amines, thiols, hydrazines and phosphine oxide solvents. A temperature-dependent study of an ethaline-based deep eutectic solvent (DES) is conducted to elucidate the characteristics of associated chemical shifts and vibrations and to determine changes in hydrogen bonding interactions using structural and thermal analytical techniques. The results suggest that ethaline is a strong candidate as a greener solvent for the synthesis of NCs at relatively low temperatures. The electronic structures of all four Cu-Sb-S phases-Cu3SbS4, CuSbS2, Cu3SbS3, and Cu12Sb4S13-were simulated using the Vienna <I>ab initio</I> Simulation (VASP) code, projector augmented-wave (PAW) potentials and the hybrid functional method (HSE 06) and using density functional theory for combined theoretical and experimental studies. Discrepancies between the experimental and theoretical bandgap values of 0.29, 0.18, 0.12 and 0.16 eV were observed for Cu3SbS4, CuSbS2, Cu3SbS3 and Cu12Sb4S13 compounds, respectively. A photoelectrochemical (PEC) water reduction system with a Mo/photoelectrode/CdS/Pt/electrolyte configuration generated a cathodic photocurrent of −1.28 and −2.72 mA cm<SUP>−2</SUP> for Cu3SbS4 and CuSbS2 electrodes, respectively, at 0 V <I>versus</I> the reversible hydrogen electrode (VRHE) under AM 1.5 G illumination, demonstrating the great potential of NCs prepared <I>via</I> eutectic solvent-mediated synthesis. This is the first successful attempt to apply eutectic solvent-mediated Cu-Sb-S NCs for solar driven H2 production. These outcomes suggest that designing proper functional materials through the application of greener synthesis strategies can improve water-splitting performance and would help meet the perpetual technological need for greener methods.</P>

Effect of controlled tacticity of polyacrylonitrile (co)polymers on their thermal oxidative stabilization behaviors and the properties of resulting carbon films

Ghorpade, Ravindra V.,Cho, Dong Won,Hong, Sung Chul Elsevier 2017 Carbon Vol.121 No.-

<P>Due to the spatial alignment of the nitrile groups and their involvement in the cyclization reactions during thermal oxidative stabilization (TOS) procedures, stereoregularity of polyacrylonitrile (PAN) precursors is one of the most important structural parameters to afford carbon materials. To elucidate this, PAN and poly(acrylonitrile-co-itaconic acid) with higher degree of isotacticity were prepared through template-assisted free-radical polymerization in the presence of MgCl2. Fourier-transform infrared spectroscopy was employed to quantitatively track the structural evolutions of the PAN (co) polymer precursors during their TOS procedures. The improved TOS efficiencies of the precursors were evidenced by high extents of cyclization, high concentrations of cyclized rings and enhanced oxygen uptakes of the isotactic PAN (co) polymers during the TOS procedures. The isotactic PAN (co) polymer precursors also exhibited relatively large heat evolutions with broad exothermic curves in differential scanning calorimetry observations, further suggesting efficient TOS procedures with safer processing conditions. The efficient TOS procedures of the isotactic PAN (co) polymer precursors resulted in carbon materials with high degrees of crystallinity and high amounts of sp(2) clusters, affording much improved electrical conductivities. This study provided knowledge on the structural characteristics of the precursors for carbon materials with pre-designed properties, which is critical for their success in high-end applications. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Wurtzite CZTS nanocrystals and phase evolution to kesterite thin film for solar energy harvesting

Ghorpade, Uma V.,Suryawanshi, Mahesh P.,Shin, Seung Wook,Hong, Chang Woo,Kim, Inyoung,Moon, Jong H.,Yun, Jae Ho,Kim, Jin Hyeok,Kolekar, Sanjay S. The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.30

<P>A quaternary indium- and gallium-free kesterite (KS)-based compound, copper zinc tin sulfide (Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB>, CZTS), has received significant attention for its potential applications in low cost and sustainable solar cells. It is well known that the reaction time, reactivity of the precursors, and types of capping ligands used during the synthesis of colloidal nanocrystals (NCs) strongly influence the crystallographic phase of the NCs. In this research, a non-toxic and green synthetic strategy for both the synthesis of CZTS NCs and the fabrication of a highly efficient CZTS absorber layers using an ink formulation without a toxic solvent, which meets the comprehensive framework for green chemistry that covers major aspects of the environmental strain, is demonstrated. In particular, pure metastable wurtzite (WZ) CZTS NCs are synthesized using the environmentally harmless, polyol mediated hot-injection (HI) technique at a low reaction temperature. The influence of the reaction time on the properties of the CZTS NCs is investigated in detail. Based on detailed reaction time dependent phase evolution, a possible growth and formation mechanism is proposed. Furthermore, a scalable, low cost, binder free ink formulation process without ligand exchange is developed using ethanol as the dispersal solvent. The as-prepared WZ-derived CZTS NC thin films are observed to undergo a phase transformation to KS during annealing in a sulfur vapor atmosphere <I>via</I> rapid thermal annealing above 500 °C, and surprisingly, this process results in fully sintered, compact and uniform CZTS thin films with large sized grains. The best solar cell device fabricated using a CZTS absorber that was sulfurized at an optimized temperature exhibits a power conversion efficiency of 2.44%, which is the highest efficiency obtained using the polyol-based HI route.</P> <P>Graphic Abstract</P><P>A quaternary indium- and gallium-free kesterite (KS)-based compound, copper zinc tin sulfide (Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB>, CZTS), has received significant attention for its potential applications in low cost and sustainable solar cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cp02007g'> </P>

Reactivity of different cement minerals in presence of Fe(II) for reducing trichloroethylene

Ghorpade, Praveen A.,Kim, Jung-Hwan,Choi, Won-Ho,Park, Joo-Yang Taylor Francis 2014 Desalination and Water Treatment Vol. No.

Carbonization behavior of poly(acrylonitrile-co-itaconic acid)s having different compositions

( Ghorpade Ravindra ),조동원,홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Copolymers of acrylonitrile with itaconic acid were prepared by free radical polymerization. Thermal stabilization of copolymers was carried out at different temperatures, followed by carbonization processes. Effect of different compositions of poly(acrylonitrile-co-itaconic acid) on structural characteristics of the carbon materials were investigated by XRD, FT-IR, Raman and 4-point probe analysis. Although increased IA content in PAIs resulted in reduced carbon yield, improved growth of carbon basal plane was observed, affording low electronic resistivity. This study was expected to afford information on optimum composition of PAI precursor for high performance carbon materials.

Structure controlled carbon nanofiber mat as a counter electrode for dye-sensitized solar cells

( Ghorpade Ravindra ),김건희,박소현,( Mallinath S. Birajdar ),이종휘,홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Carbonaceous materials have been investigated as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). In this study, nanofiber mats composed of polyacrylonitrile (co)polymer and Pt precursors were prepared by electrospinning method. Series of thermal treatment on the mats, such as thermal oxidative stabilization, carbonization and graphitization, afforded structure-controlled carbon nanofiber/Pt mats with high electrical conductivity, large surface area and high catalytic activity. The carbon nanofiber/Pt mat was introduced in DSSC as a CE by using adhesives without major structural deformations. The DSSC exhibited good performance including high energy conversion efficiency, which was comparable to that of conventional DSSC with all Pt CE.