Nitrogen-rich hollow carbon spheres decorated with FeCo/fluorine-rich carbon for high performance symmetric supercapacitors

Karuppannan, Mohanraju,Kim, Youngkwang,Sung, Yung-Eun,Kwon, Oh Joong The Royal Society of Chemistry 2018 Journal of materials chemistry. A, Materials for e Vol.6 No.17

<P>A novel approach to fluorine-rich carbon (FC) shell formation on an electron-rich metal surface based on the electronegativity concept is reported. Basically, highly electronegative elements are strongly attracted by low electronegative/electron-rich elements through dipole interaction, which leads to the formation of fluorine-rich carbon shells on metals at various fluorine quantities. Herein, nitrogen-rich hollow carbon spheres decorated with fluorine-rich carbon shell covered metals (FC@M/NHCS, M = Fe, Co, and FeCo) were synthesized by co-polymerization on SiO2, adsorption of metal precursors, and etching of the SiO2, followed by sintering. The fluorine content, quantified by XPS and SEM-EDS studies, decreased according to FeCo > Fe > Co in FC@M/NHCS. HAADF-STEM elemental mapping studies clearly confirmed fluorine-rich carbon shell formation on the metal surface. The influence of fluorine content order in the as-synthesized materials was reflected in their capacitance performances. FC@FeCo/NHCS electrode depicted the maximum specific capacitance of 302.0 F g<SUP>−1</SUP> at 0.2 A g<SUP>−1</SUP> in 6 M KOH medium, delivering excellent stability with no losses over 5000 cycles at 5 A g<SUP>−1</SUP>. The symmetric supercapacitor (SSC) devices operated at 1.5 V by delivering maximum device specific capacitance of 51.2 F g<SUP>−1</SUP> at 0.2 A g<SUP>−1</SUP>. It exhibited 81.3% of capacitance retention at 10 A g<SUP>−1</SUP> with the FC@FeCo/NHCS. The maximum energy density of 15.3 W h kg<SUP>−1</SUP> at 0.2 A g<SUP>−1</SUP> and the maximum power density of 5100 W kg<SUP>−1</SUP> at 10 A g<SUP>−1</SUP> were delivered by the FC@FeCo/NHCS device. This study provides an ideal way for synthesizing fluorine-rich carbon materials for high energy storage/conversion applications.</P>

아닐린 기반 탄소껍질을 이용한 백금 나노입자 표면처리

곡수진,( Mohanraju Karuppannan ),김영광,권오중 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

본 연구에서는 탄소 껍질로 둘러 쌓인 백금 나노 입자를 만들기 위하여 백금-아닐린 복합체를 활용하였으며, 탄소 나노 섬유(CNF)를 이용하여 탄소껍질 형성 시 촉매들의 뭉침을 방지하였다. 탄소 나노 섬유 위에 올린 백금-아닐린 복합체는 다양한 열처리 온도에서 아닐린의 탄화를 진행하였다. 합성된 촉매는 X-선 회절 분석법(XRD), X선 광전자 분광법(XPS)과 투과전자현미경(TEM) 분석을 통해 열처리 온도에 따라 달라지는 촉매의 결정 크기 및 특성을 비교 할 수 있었고, 열 중량 분석기(TGA)의 분석을 통해 백금을 감싸고 있는 탄소의 양을 비교 할 수 있었다. 합성된 촉매의 반쪽전지 실험을 통해 탄소 껍질에 의한 백금 촉매의 내구성 향상과 반응물에 따른 선택도를 확인 할 수 있었다. 백금 촉매의 내구성과 반응물에 대한 선택도는 열처리 온도에 따라 달라지는 것을 확인할 수 있었으며 그러한 특성을 가지게 되는 원인을 분석할 수 있었다. 본 연구는 촉매의 내구성을 향상시키는 탄소 껍질을 형성하는 새로운 방법을 제시할 뿐만 아니라 이러한 탄소 껍질에 의하여 반응물에 대한 선택도도 부여할 수 있음을 제시하고 있다.

Development of high-performance membrane-electrode assembly in unitized regenerative fuel cells

박지은,Mohanraju Karuppannan,권오중,조영훈,성영은 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

In this work, we investigated the membrane-electrode assembly (MEA) parameters of an oxygenelectrode to develop a high-performance unitized regenerative fuel cell (URFC) that can be operated infuel cell (FC) and water electrolysis (WE) mode. The MEA parameters including gas diffusion layer,ionomer content, oxygen reduction reaction (ORR) type, oxygen evolution reaction (OER) catalyst, andcatalyst loading were optimized by calculating the round-trip efficiency of URFC. The performance in FCmode was largely affected by the MEA parameters compared to that of the WE mode performance. The FCmode performance is crucial for the achievement of high URFC performance. The optimized round-tripefficiency was 49% at 500 mA cm 2, which is comparable or superior to that reported in literature. Thisresult can be attributed to the highly efficient MEA structure suitable for bifunctional catalysts toparticipate in both ORR and OER.

Direct formation of Pt catalyst on gas diffusion layer using sonochemical deposition method for the application in polymer electrolyte membrane fuel cell

Kim, Youngkwang,Karuppannan, Mohanraju,Sung, Yung-Eun,Lim, Taeho,Kwon, Oh Joong Elsevier 2018 International journal of hydrogen energy Vol.43 No.22

<P><B>Abstract</B></P> <P>In this study, the facile and direct formation of platinum catalyst on a carbon paper (gas diffusion layer) via the sonochemical deposition method is demonstrated. An ultrasound irradiation with a carbon paper substrate in a platinum precursor solution formed interconnected platinum grains on the carbon paper surface. The surface morphology and deposition amount of platinum were strong functions of both ultrasound parameters (power and time) and solution composition. The platinum-deposited carbon paper was then directly used as a gas diffusion electrode in PEMFC without adding the ionomer. This exhibited high stability in the accelerated stress test in a single cell operation. The interconnected grains of platinum on carbon paper had high resistance to dissolution in an oxidizing environment and the absence of carbon support also enhanced resistance to carbon oxidation. Although the overall performance did not exceed that of the commercial Pt/C, this approach may be an option to form a stable platinum catalyst for PEMFCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A Pt catalyst was formed directly on a carbon paper via sonochemical deposition. </LI> <LI> The sonochemical deposition formed interconnected grains of Pt on the carbon paper surface. </LI> <LI> The sonochemical deposition condition was optimized for obtaining a uniform Pt catalyst. </LI> <LI> The Pt catalyst/carbon paper showed superior durability to Pt/C in a single cell test. </LI> </UL> </P>

The energy band alignment at the interface between mechanically exfoliated few-layer NiPS3 nanosheets and ZnO

Cheng-Tai Kuo,Karuppannan Balamurugan,Hung Wei Shiu,Hyun Ju Park,Soobin Sinn,Michael Neumann,한문섭,장영준,Chia-Hao Chen,Hyeong-Do Kim,박제근,Tae Won Noh 한국물리학회 2016 Current Applied Physics Vol.16 No.3

We have studied the electronic structure and interfacial properties of mechanically exfoliated few-layer NiPS3 van der Waals crystals on ZnO/Nb:SrTiO3 substrates using scanning photoelectron microscopy and spectroscopy. The conducting ZnO layer enhances the visibility of few-layer NiPS3 on Nb:SrTiO3 and prevents charging effects in photoemission. We experimentally determined a type-II band alignment at the NiPS3/ZnO interface. The valence band offset (VBO) of few-layer NiPS3/ZnO is 2.8 ± 0.09 eV, and the conduction band offset is 1.0 ± 0.09 eV. Moreover, we found an increase of ~0.3 eV in VBO as decreasing NiPS3 thickness, suggesting electronic coupling or charge transfer at the NiPS3/ZnO interface.

Impact of fatigue on quality of life among breast cancer patients receiving chemotherapy

Fares Mohammed Saeed Muthanna,Mahmathi Karuppannan,Bassam Abdul Rasool Hassan,Ali Haider Mohammed 질병관리본부 2021 Osong Public Health and Research Persptectives Vol.12 No.2

Objectives: Fatigue is the most frequently reported symptom experienced by cancer patients and has a profound effect on their quality of life (QOL). The study aimed to determine the impact of fatigue on QOL among breast cancer patients receiving chemotherapy and to identify the risk factors associated with severe fatigue incidence. Methods: This was an observational prospective study carried out at multiple centers. In total, 172 breast cancer patients were included. The Functional Assessment of Chronic Illness Therapy-Fatigue Questionnaire was used to measure QOL, while the Brief Fatigue Inventory (BFI) was used to assess the severity of fatigue. Results: The total average mean and standard deviation of QOL were 84.58±18.07 and 4.65±1.14 for BFI scores, respectively. A significant association between fatigue and QOL was found in linear and multiple regression analyses. The relationships between fatigue severity and cancer stage, chemotherapy dose delay, dose reduction, chemotherapy regimen, and ethnicity were determined using binary logistic regression analysis. Conclusion: The findings of this study are believed to be useful for helping oncologists effectively evaluate, monitor, and treat fatigue related to QOL changes.

Polyelectrolyte complex membranes made of chitosan—PSSAMA for pervaporation separation of industrially important azeotropic mixtures

Divya Achari,Padmeshwary Rachipudi,Satishkumar Naik,Ramesh Karuppannan,Mahadevappa Kariduraganvar 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.78 No.-

Chitosan-based polyelectrolyte complex membranes (PECMs) were developed by incorporatingpolystyrene sulfonic acid-co-maleic acid (PSSAMA) in the chitosan membrane matrix as a pervaporationmembrane by employing a solution technique. Fourier transform infrared (FTIR) spectroscopy, wideangleX-ray diffraction (WAXD), thermogravimetry analysis (TGA), differential scanning calorimetry(DSC), and scanning electron microscopy (SEM) were used to characterize the membranes. PECMs weretested for their potentiality to separate various azeotropic mixtures; water/ter-butanol, water/isopropanol, water/n-propanol and water/1, 4 dioxane at their azeotropic point. The PECMs containing9 mass% of PSSAMA manifest highest separation selectivity of 5352 with aflux of 4.145 10 2 kg /m2 h forthe azeotropic mixture of water/ter-butanol at 30 C. To confirm their stability at the higher temperature,the PECMs were assessed for pervaporation (PV) separation at 40, 50 and 60 C. For all PECMs totalfluxandflux of water appeared to be coinciding each other, signifying that PECMs could be used successfullyto break the azeotropic point of various azeotropic mixtures. The Arrhenius activation parameters weredetermined by diffusion and permeation values. The activation energy values procured for waterpermeation (Epw) were considerably lower than ter-butanol permeation (EpTBOH). The heat of sorption(DHs) values obtained for PECMs were negative, showing that Langmuir’s mode of sorption is dominant.

Effect of catalyst layer designs for high-performance and durable anion-exchange membrane water electrolysis

박지은,Hyo Eun Bae,Mohanraju Karuppannan,오강민,권오중,Yong-Hun Cho,Yung-Eun Sung 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

Development of anode design is crucial for highly efficient and durable anion-exchange membrane waterelectrolysis (AEMWE) as the kinetic of oxygen evolution reaction (OER) is sluggish. In this study, a macroporouscatalyst layer (macroporous_CL) was proposed as an anode design for AEMWE to enhance the catalystutilization. A macroporous_CL contains pores of two main size ranges: hundreds of nanometers and hundredsof micrometers. It is prepared using a spraying method to form nanometer-sized pores. The use ofa stainless-steel (SUS) porous transport layer (PTL) as the substrate of the spraying method producesmicrometer-sized macropores. In an investigation of the effects of the macroporous_CL and conventionalcatalyst layer (plain_CL) on AEMWE using two different kinds of oxygen evolution reaction (OER) catalysts,the macroporous_CL exhibited higher performance with lower ohmic and charge-transfer resistances comparedto the plain_CL. This performance enhancement was attributed to the improved catalyst utilizationand electron transport. Also, the macroporous_CL showed better durability compared to the plain_CL. Therefore, the macroporous_CL has been considered as an alternative anode design for AEMWE.

Spectral characterization of a pteridine derivative from cyanide-utilizing bacterium Bacillus subtilis - JN989651

S. Durairaju Nisshanthini,Antony K. Teresa Infanta S.,Duraisamy Senthil Raja,Karuppannan Natarajan,M. Palaniswamy,Jayaraman Angayarkanni 한국미생물학회 2015 The journal of microbiology Vol.53 No.4

Soil and water samples were collected from various regionsof SIPCOT and nearby Vanappadi Lake, Ranipet, Tamilnadu,India. Based on their colony morphology and their stabilityduring subculturing, 72 bacteria were isolated, of which 14isolates were actinomycetes. Preliminary selection was carriedout to exploit the ability of the microorganisms to utilizesodium cyanate as nitrogen source. Those organismsthat were able to utilize cyanate were subjected to secondaryscreening viz., utilization of sodium cyanide as the nitrogensource. The oxygenolytic cleavage of cyanide is dependenton cyanide monooxygenase which obligately requires pterincofactor for its activity. Based on this, the organisms capableof utilizing sodium cyanide were tested for the presence ofpterin. Thin layer chromatography (TLC) of the cell extractsusing n-butanol: 5 N glacial acetic acid (4:1) revealed that10 out of 12 organisms that were able to utilize cyanide hadthe pterin-related blue fluorescent compound in the cellextract. The cell extracts of these 10 organisms were subjectedto high performance thin layer chromatography (HPTLC)for further confirmation using a pterin standard. Based onthe incubation period, cell biomass yield, peak height andarea, strain VPW3 was selected and was identified as Bacillussubtilis. The Rf value of the cell extract was 0.73 which wasconsistent with the 0.74 Rf value of the pterin standardwhen scanned at 254 nm. The compound was extracted andpurified by preparative High Performance Liquid Chromatography(HPLC). Characterization of the compound wasperformed by ultraviolet spectrum, fluorescence spectrum,Electrospray Ionization-Mass Spectrometry (ESI-MS), andNuclear Magnetic Resonance spectroscopy (NMR). The compoundis proposed to be 6-propionyl pterin (2-amino-6-propionyl-3H-pteridin-4-one).

Si/ZnO heterostructures for efficient diode and water-splitting applications

Mitta, Sekhar Babu,Murahari, Prashantha,Nandanapalli, Koteeswara Reddy,Mudusu, Devika,Karuppannan, Ramesh,Whang, Dongmok Elsevier 2018 International journal of hydrogen energy Vol.43 No.33

<P><B>Abstract</B></P> <P>We have developed thin zinc oxide (ZnO) layers protected highly conductive p-type silicon (Si) electrodes and investigated their diode and photoanode characteristics. ZnO layers have been deposited on the glass as well as p-Si substrates at a temperature of 400 °C by pulsed spray pyrolysis method. The crystal structure, surface morphology, and phase purity of the layers along with electrical characteristics of the heterostructures were investigated. Finally, the photocatalytic water oxidation performance of the ZnO/Si structures was studied in an alkaline electrolyte solution (pH = 10). The as-grown devices exhibited excellent diode characteristics with a turn-on voltage of 4.5 V, and applied bias-voltage dependent carrier transport mechanisms. As compared to bare Si, ZnO coated Si-based PEC devices showed good stability and durability along with very low onset potential of 0.07 V versus Ag/AgCl.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Si/ZnO heterostructures are developed and investigated. </LI> <LI> Structures possess significant diode and PEC properties. </LI> <LI> As compared to bare Si, good photoanodes stability and durability are observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Ultrathin ZnO layers coated Si electrodes prepared by pulsed spray pyrolysis. These heterostructures exhibited excellent p-n junction diode characteristics along with good stability as well as durability as photoanodes in an alkaline electrolyte.</P> <P>[DISPLAY OMISSION]</P>