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Bose, Ranjith,Seo, Minho,Jung, Chi-Young,Yi, Sung Chul Elsevier 2018 ELECTROCHIMICA ACTA Vol.271 No.-
<P><B>Abstract</B></P> <P>Hydrogen evolution reaction (HER) using earth abundant catalyst is one of the most promising approaches to replace precious platinum (Pt) and Pt-based catalysts for a green-energy environment. In this work, the HER performance of pristine MoS<SUB>2</SUB> is enhanced by doping of Co and Se atoms, which serve as additional active sites and oxygen defects on HER performance respectively, thereby tuning the electronic structure of pristine MoS<SUB>2</SUB> and further optimizing its hydrogen adsorption energy. The structural and morphological characterizations reveal the presence of the cuboid and raspberry nanostructures with a high order of crystallinity and extended interlayer spacing. The Co- and Se-doped MoS<SUB>2</SUB>, display enhanced HER activity than pristine MoS<SUB>2</SUB> with a low onset potential of 181 mV and 166 mV, and a low overpotential of 218 mV and 207 mV at a cathodic current density of 10 mA cm<SUP>−2</SUP>. More importantly, the Se-doped MoS<SUB>2</SUB> shows good catalytic stability with a low Tafel slope of 44 mV dec<SUP>−1</SUP> as compared with that of Co-doped MoS<SUB>2</SUB> (50 mV dec<SUP>−1</SUP>) and other reported values in the literature. Furthermore, the density functional theory calculations were carried out to get a fundamental understanding of electrocatalytic activity of Co and Se doping onto MoS<SUB>2</SUB>. This work can serve as a general methodology to enhance HER activity for the upcoming potential catalysts in the future and may uncover several applications in the field of solar photo-electrochemical (PEC) water-splitting cells and proton exchange membrane (PEM) electrolyzers.</P>
Ranjith Bose,김재민,김태현,고범수,고낙규,문준영,이성철 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.11
For lithium-ion batteries (LIBs), MoS2, which has conversion reaction pathways that can accommodate lithium ions during charge, is a very special inorganic material that has a two-dimensional planar structure similar to graphite. For reliable performance of high-energy LIBs, Se–molybdenum chalcogenides with sulfide and selenide (Se–MC) were prepared via the incorporation of a carbon nanotube (CNT) conducting matrix to solve the crucial limitations of MoS2, which include poor electronic conductivity and severe volume changes during cycling. For the preparation of Se–MC/CNT, a facile, one-pot synthetic method using molybdic acid, selenium dioxide, and thioacetamide, which are the precursors for molybdenum, selenide, and sulfide, respectively, and CNT was developed. A detailed investigation of the surfaces and crystal structures of the prepared samples was conducted using transmission electron microscopy and X-ray photoelectron spectroscopy analyses. Furthermore, LIBs containing the Se–MC/CNT exhibited a significantly extended cycle life and an improved rate capability that revealed the synergetic effect of the CNTs and selenide for controlling the morphology.
( Ranjith Bose ),이성철 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Development of highly active, cost effective, stable and earth abundant electrocatalyst for hydrogen evolution reaction (HER) is still a major challenge for energy conversion technologies. At present, MoS<sub>2</sub> and its derivatives have attracted intensive interest due to its excellent catalytic performance. However, improving the overall catalytic activity of structural modified MoS<sub>2</sub> is still remains a key challenge for further reducing a overpotential for the HER of electrochemical water splitting. In this regard, we report a surface modified molybdenum sulphoselenide with phosphorous on carbon fiber paper (P-MoS<sub>x</sub>Se<sub>y</sub>/CFP) for the HER. Remarkably, P-MoS<sub>x</sub>Se<sub>y</sub>/CFP electrode delivered a low over potential (η) of 93 mV at a current density (j) of 10 mA/㎠ in 0.5M H<sub>2</sub>SO<sub>4</sub>, when compared with MoS<sub>2</sub>/CFP (η=242 mV @ 10 mA/cm2), MoS<sub>x</sub>Se<sub>y</sub>/CFP (η=200 mV @ 10 mA/㎠). Moreover, the observed HER activity of P-MoS<sub>x</sub>Se<sub>y</sub>/CFP has outperformed over the current molybdenum phosphides and chalcogenides catalysts
Bose, Ranjith,Balasingam, Suresh Kannan,Shin, Seokhee,Jin, Zhenyu,Kwon, Do Hyun,Jun, Yongseok,Min, Yo-Sep American Chemical Society 2015 Langmuir Vol.31 No.18
<P>Amorphous molybdenum sulfide (MoS<SUB><I>x</I></SUB>) has been identified as an excellent catalyst for the hydrogen evolution reaction (HER). It is still a challenge to prepare amorphous MoS<SUB><I>x</I></SUB> as a more active and stable catalyst for the HER. Here the amorphous MoS<SUB><I>x</I></SUB> catalysts are prepared on carbon fiber paper (CFP) substrates at 200 °C by a simple hydrothermal method using molybdic acid and thioacetamide. Because the CFP is intrinsically hydrophobic due to its graphene-like carbon structure, two kinds of hydrophilic pretreatment methods [plasma pretreatment (PP) and electrochemical pretreatment (EP)] are investigated to convert the hydrophobic surface of the CFP to be hydrophilic prior to the hydrothermal growth of MoS<SUB><I>x</I></SUB>. In the HER catalysis, the MoS<SUB><I>x</I></SUB> catalysts grown on the pretreated CFPs reach a cathodic current density of 10 mA/cm<SUP>2</SUP> at a much lower overpotential of 231 mV on the MoS<SUB><I>x</I></SUB>/EP-CFP and 205 mV on the MoS<SUB><I>x</I></SUB>/PP-CFP, compared to a high overpotential of 290 mV on the MoS<SUB><I>x</I></SUB> of the nonpretreated CFP. Turnover frequency per site is also significantly improved when the MoS<SUB><I>x</I></SUB> are grown on the pretreated CFPs. However, the Tafel slopes of all amorphous MoS<SUB><I>x</I></SUB> catalysts are in the range of 46–50 mV/dec, suggesting the Volmer–Heyrovsky mechanism as a major pathway for the HER. In addition, regardless of the presence or absence of the pretreatment, the hydrothermally grown MoS<SUB><I>x</I></SUB> catalyst on CFP exhibits such excellent stability that the degradation of the cathodic current density is negligible after 1000 cycles in a stability test, possibly due to the relatively high growth temperature.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2015/langd5.2015.31.issue-18/acs.langmuir.5b00205/production/images/medium/la-2015-00205r_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la5b00205'>ACS Electronic Supporting Info</A></P>
Bose, Ranjith,Patil, Bebi,Rajendiran Jothi, Vasanth,Kim, Tae-Hyun,Arunkumar, Paulraj,Ahn, Heejoon,Yi, Sung Chul THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.65 No.-
<P><B>Abstract</B></P> <P>Co<SUB>3</SUB>Se<SUB>4</SUB> on nitrogen doped carbon nanotube (N-CNT) with applications for supercapacitor and hydrogen evolution reaction (HER) is synthesized by pyrolysis and solvothermal processes. The catalyst due to improved electrical conductivity and increased rate of removal of H<SUB>2</SUB> liberated, delivers a high HER activity, by reaching <I>η</I> <SUB>10</SUB> at 174mV and 240mV, Tafel slope of 73.2 and 43.8mVdec<SUP>−1</SUP> in alkaline and acidic medium respectively. Co<SUB>3</SUB>Se<SUB>4</SUB>/N-CNT as supercapacitor electrodes, yields a capacitance of 114Fg<SUP>−1</SUP> at a 2mVs<SUP>−1</SUP> scan rate, with an excellent capacitive retention of 96% of the initial capacitance after 5000 cycles.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ranjith Bose,Bebi Patil,바산트라젠디란조띠,김태현,PAULRAJARUN KUMAR,안희준,이성철 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-
Co3Se4 on nitrogen doped carbon nanotube (N-CNT) with applications for supercapacitor and hydrogen evolution reaction (HER) is synthesized by pyrolysis and solvothermal processes. The catalyst due to improved electrical conductivity and increased rate of removal of H2 liberated, delivers a high HER activity, by reaching η10 at 174 mV and 240 mV, Tafel slope of 73.2 and 43.8 mV dec−1 in alkaline and acidic medium respectively. Co3Se4/N-CNT as supercapacitor electrodes, yields a capacitance of 114 F g−1 at a 2 mV s−1 scan rate, with an excellent capacitive retention of 96% of the initial capacitance after 5000 cycles.
Kim, Tae-Hyun,Jung, Chi-Young,Bose, Ranjith,Yi, Sung-Chul Elsevier 2018 Carbon Vol.139 No.-
<P><B>Abstract</B></P> <P>In this paper, cobalt encapsulated in nitrogen and sulfur co-doped carbon nanotube (Co-NST) was synthesized through a simple pyrolysis method to impregnate platinum (Pt) nanoparticles. The Co-NST presented a bamboo-like morphology with the high degree of graphitization. Owing to the dual heteroatoms co-doped in the carbon matrix, the Pt supported on the Co-NST (Pt/Co-NST) showed the well-dispersed morphology of the Pt nanoparticles. In addition, the synergistic effect between the Co-NST support and the Pt nanoparticle was observed from the physicochemical characterizations. As a result, the Pt/Co-NST presented improved oxygen reduction reaction (ORR) activity and stability compared to the commercial Pt/C. The mass activity and specific activity of the Pt/Co-NST presented 508.48 mA mg<SUB>Pt</SUB> <SUP>−1</SUP> and 723.93 μA cm<SUB>Pt</SUB> <SUP>−2</SUP>, respectively, which exhibited more than 3 times higher compared to those of the commercial Pt/C. After repeating 5000 potential cycles, the Pt/Co-NST showed improved stability with 29 mV loss in half-wave potential, while the half-wave potential of the commercial Pt/C was severely decreased by 118 mV.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Karuppasamy, K.,Prasanna, K.,Ilango, P. Robert,Vikraman, Dhanasekaran,Bose, Ranjith,Alfantazi, Akram,Kim, Hyun-Seok Elsevier 2019 Journal of industrial and engineering chemistry Vol.80 No.-
<P><B>Abstract</B></P> <P>In the present work, a porous nano-carbon (PNC) based electrode materials were successfully derived from the natural biopolymer phytagel via a facile hydrothermal and combustion process. The carbon phase structure of the PNC electrode was confirmed using different spectroscopy, microscopy and N<SUB>2</SUB> adsorption-desorption analyses. The surface morphology investigation showed a distinct shape and size for the PNC that demonstrated its porous nature. The electrochemical performance of PNC was completely reliant on the calcination temperature (800°C) and it delivered the maximum capacitance of 122Fg<SUP>−1</SUP> at 0.25Ag<SUP>−1</SUP>. An AC impedance and cyclic voltammetry analyses proved the intrinsic electrochemical behavior by their cycling. Besides, the fabricated symmetric solid-state supercapacitor displayed an outstanding cycle durability with a stable capacitance retention of 85.8% over 8000 cycles, suggesting favorable prospects for its use as an active candidate for symmetric solid-state supercapacitor applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>