Highly flexible pseudocapacitor based on freestanding heterogeneous MnO₂/conductive polymer nanowire arrays

Duay, Jonathon,Gillette, Eleanor,Liu, Ran,Lee, Sang Bok The Royal Society of Chemistry 2012 Physical chemistry chemical physics Vol.14 No.10

<P>Flexible electronics such as wearable electronic clothing, paper-like electronic devices, and flexible biomedical diagnostic devices are expected to be commercialized in the near future. Flexible energy storage will be needed to power these devices. Supercapacitor devices based on freestanding nanowire arrays are promising high power sources for these flexible electronics. Electrodes for these supercapacitor devices consisting of heterogeneous coaxial nanowires of poly (3,4-ethylenedioxythiophene) (PEDOT)-shell and MnO<SUB>2</SUB>-core materials have been shown in a half cell system to have improved capacitance and rate capabilities when compared to their pure nanomaterials; however, their performance in a full cell system has not been fully investigated. Herein, these coaxial nanowires are tested in both a symmetric and an asymmetric (utilizing a PEDOT nanowire anode) full cell configuration in the aspect of charge storage, charge rate, and flexibility without using any carbon additives and polymer binders. It is found that the asymmetric cell outperforms the symmetric cell in terms of energy density, rate capability, and cycle ability. The asymmetric device's electrode materials display an energy density of 9.8 Wh/kg even at a high power density of 850 W kg<SUP>−1</SUP>. This device is highly flexible and shows fast charging and discharging while still maintaining 86% of its energy density even under a highly flexed state. The total device is shown to have a total capacitance of 0.26 F at a maximum voltage of 1.7 V, which is capable of providing enough energy to power small portable devices.</P> <P>Graphic Abstract</P><P>Highly flexible supercapacitor device using MnO<SUB>2</SUB>/conductive polymer coaxial nanowire arrays with a practical capacitance of 0.26 F at a voltage of 1.7 V. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cp00019a'> </P>

Self-Limiting Electrodeposition of Hierarchical MnO₂ and M(OH)₂/MnO₂ Nanofibril/Nanowires: Mechanism and Supercapacitor Properties

Duay, Jonathon,Sherrill, Stefanie A.,Gui, Zhe,Gillette, Eleanor,Lee, Sang Bok American Chemical Society 2013 ACS NANO Vol.7 No.2

<P>Hierarchical nanostructures have generated great interest in the energy, materials, and chemical sciences due to the synergic properties of their composite architectures. Herein, a hierarchical MnO<SUB>2</SUB> nanofibril/nanowire array is successfully synthesized. The structure consists of a conformal layer of MnO<SUB>2</SUB> nanofibrils evenly distributed on the surface of the individual MnO<SUB>2</SUB> nanowires. The synthetic mechanism of this hierarchical structure is characterized by electrochemical measurements, Raman spectroscopy, EELS, and electron microscopy. This material was then investigated at slow scan rates for its charge storage mechanisms in different solvents. In aqueous electrolyte, the nanofibrils show a capacitance almost purely dedicated to double-layer and surface adsorption processes, while in an acetonitrile electrolyte, the nanofibrils’ capacitance comes mainly from a cation insertion process. This material was also tested at high scan rates in aqueous solution for its practical supercapacitor capabilities. The material shows a large capacitance of 298 F/g at 50 mV/s and 174 F/g at 250 mV/s. It also maintains 85.2% of its capacitance after 1000 cycles. The material also displays easily controllable parameters such as nanowire length, nanowire diameter, and amount of nanofibril material which is shown here to affect the capacitance dramatically.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-2/nn3056077/production/images/medium/nn-2012-056077_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn3056077'>ACS Electronic Supporting Info</A></P>

Perceived Relevance of Chemistry Topics to Everyday Life: Inputs to Context Based Enrichment Activities in General and Inorganic Chemistry

Butch Stephen C. Duay ASCONS 2017 INTERNATIONAL JOURNAL OF EMERGING MULTIDISCIPLINAR Vol.1 No.1

The purpose of this study stressed on the challenge of developing context-based enrichment activities that will make connections between the concepts taught in the General and Inorganic Chemistry course taken by the General Engineering students at the Bulacan State University-Bustos Campus. The sample of the study included 50 second year General Engineering students from Bulacan State University – Bustos Campus as well as 10 chemistry instructors from the Meneses, Bustos and Malolos campuses of Bulacan State University. A need analysis and evaluation sheet of the developed contextbased enrichment activities in General and Inorganic Chemistry adapted in the study of Basilio (2006) and in consonance to the characteristics of Contextual Teaching and Learning defined by Wilson and Clifford (2000) were used to collect data related to the needs of the students to come up with an instructional material that will connect chemistry concepts to their lives and to validate the developed enrichment activities respectively. Results revealed the topics that has high relevance to the students were, gas laws, physical changes, conversion of units, factors affecting rate of solution, factors affecting solubility, types of solution, properties of solutions, variables in gases, chemical changes, substances and mixtures, states of matter, factors affecting reaction rates, types of chemical reactions, compounds, elements, ways of separating mixtures, pH and pOH, rate of reaction, colloids and concentration of solution, and these are the topics contained in the enrichment activities. The students also replied that there is a need to come up with an instructional material that will connect these concepts to their lives since these are fundamental concepts and the contextual approach will aid the convenience of learning such concepts and to enhance enduring knowledge. The evaluation of the instructors to the enrichment activities scored an acceptable mark and was commended as useful and applicable.

Electrochemical Formation Mechanism for the Controlled Synthesis of Heterogeneous MnO₂/Poly(3,4-ethylenedioxythiophene) Nanowires

Liu, Ran,Duay, Jonathon,Lee, Sang Bok American Chemical Society 2011 ACS NANO Vol.5 No.7

<P>The formation mechanism of a coaxial manganese oxide/poly(3,4-ethylenedioxythiophene) (MnO<SUB>2</SUB>/PEDOT) nanowire is elucidated herein by performing electrodeposition of MnO<SUB>2</SUB> and PEDOT on Au-sputtered nanoelectrodes with different shapes (ring and flat-top, respectively) within the 200 nm diameter pores of an anodized aluminum oxide (AAO) template. It is found that PEDOT prefers to grow on the sharp edge of the ring-shaped electrode, while MnO<SUB>2</SUB> is more likely to deposit on the flat-top electrode due to its smooth surface. The formation of coaxial nanowires is shown to be a result of simultaneous growth of core MnO<SUB>2</SUB> and shell PEDOT by an analysis of the current density resulting from electrochemical deposition. Furthermore, the structures of the MnO<SUB>2</SUB>/PEDOT coaxial nanowires were studied for their application as supercapacitors by modifying their coelectrodeposition potential. A potential of 0.70 V is found to be the most favorable condition for synthesis of MnO<SUB>2</SUB>/PEDOT coaxial nanowires, resulting in a high specific capacitance of 270 F/g. Additionally, other heterogeneous MnO<SUB>2</SUB>/PEDOT nanostructures are produced, such as nanowires consisting of MnO<SUB>2</SUB> nanodomes with PEDOT crowns as well as segmented MnO<SUB>2</SUB>/PEDOT nanowires. This is accomplished by simply adjusting the parameters of the electrochemical deposition. Finally, in smaller diameter (50 nm) AAO channels, MnO<SUB>2</SUB> and PEDOT are found to be partially assembled into coaxial nanowires due to the alternative depletion of Mn(II) ions and EDOT monomers in the smaller diameter pores.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-7/nn201106j/production/images/medium/nn-2011-01106j_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn201106j'>ACS Electronic Supporting Info</A></P>

Redox Exchange Induced MnO₂ Nanoparticle Enrichment in Poly(3,4-ethylenedioxythiophene) Nanowires for Electrochemical Energy Storage

Liu, Ran,Duay, Jonathon,Lee, Sang Bok American Chemical Society 2010 ACS NANO Vol.4 No.7

<P>MnO<SUB>2</SUB> nanoparticle enriched poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires are fabricated by simply soaking the PEDOT nanowires in potassium permanganate (KMnO<SUB>4</SUB>) solution. The structures of these MnO<SUB>2</SUB> nanoparticle enriched PEDOT nanowires are characterized by SEM and TEM, which show that the MnO<SUB>2</SUB> nanoparticles have uniform sizes and are finely dispersed in the PEDOT matrix. The chemical constituents and bonding of these composite nanowires are characterized by energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, which indicate that the formation and dispersion of these MnO<SUB>2</SUB> nanoparticles into the nanoscale pores of the PEDOT nanowires are most likely triggered by the reduction of KMnO<SUB>4</SUB> <I>via</I> the redox exchange of permanganate ions with the functional group on PEDOT. Varying the concentrations of KMnO<SUB>4</SUB> and the reaction time controls the loading amount and size of the MnO<SUB>2</SUB> nanoparticles. Cyclic voltammetry and galvanostatic charge−discharge are used to characterize the electrochemical properties of these MnO<SUB>2</SUB> nanoparticle loaded PEDOT nanowires. Due to their extremely high exposed surface area with nanosizes, the pristine MnO<SUB>2</SUB> nanoparticles in these MnO<SUB>2</SUB> nanoparticle enriched PEDOT nanowires show very high specific capacitance (410 F/g) as the supercapacitor electrode materials as well as high Li<SUP>+</SUP> storage capacity (300 mAh/g) as cathode materials of Li ion battery, which boost the energy storage capacity of PEDOT nanowires to 4 times without causing excessive volume expansion in the polymer. The highly conductive and porous PEDOT matrix facilitates fast charge/discharge of the MnO<SUB>2</SUB> nanoparticles and prevents them from agglomerating. These synergic properties enable the MnO<SUB>2</SUB> nanoparticle enriched PEDOT nanowires to be promising electrode materials for supercapacitors and lithium ion batteries.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-7/nn1010182/production/images/medium/nn-2010-010182_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn1010182'>ACS Electronic Supporting Info</A></P>

Heterogeneous nanostructured electrode materials for electrochemical energy storage

Liu, Ran,Duay, Jonathon,Lee, Sang Bok Royal Society of Chemistry 2011 Chemical communications Vol.47 No.5

<P>In order to fulfil the future requirements of electrochemical energy storage, such as high energy density at high power demands, heterogeneous nanostructured materials are currently studied as promising electrode materials due to their synergic properties, which arise from integrating multi-nanocomponents, each tailored to address a different demand (<I>e.g.</I>, high energy density, high conductivity, and excellent mechanical stability). In this article, we discuss these heterogeneous nanomaterials based on their structural complexity: zero-dimensional (0-D) (<I>e.g.</I> core–shell nanoparticles), one-dimensional (1-D) (<I>e.g.</I> coaxial nanowires), two-dimensional (2-D) (<I>e.g.</I> graphene based composites), three-dimensional (3-D) (<I>e.g.</I> mesoporous carbon based composites) and the even more complex hierarchical 3-D nanostructured networks. This review tends to focus more on ordered arrays of 1-D heterogeneous nanomaterials due to their unique merits. Examples of different types of structures are listed and their advantages and disadvantages are compared. Finally a future 3-D heterogeneous nanostructure is proposed, which may set a goal toward developing ideal nano-architectured electrodes for future electrochemical energy storage devices.</P> <P>Graphic Abstract</P><P>Recent advances in applying heterogeneous nanostructures as electrode materials for electrochemical energy storage devices such as lithium–ion batteries and supercapacitors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cc03158e'> </P>

Synthesis and characterization of RuO₂/poly(3,4-ethylenedioxythiophene) composite nanotubes for supercapacitors

Liu, Ran,Duay, Jonathon,Lane, Timothy,Bok Lee, Sang Royal Society of Chemistry 2010 Physical chemistry chemical physics Vol.12 No.17

<P>We report the synthesis of composite RuO<SUB>2</SUB>/poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes with high specific capacitance and fast charging/discharging capability as well as their potential application as electrode materials for a high-energy and high-power supercapacitor. RuO<SUB>2</SUB>/PEDOT nanotubes were synthesized in a porous alumina membrane by a step-wise electrochemical deposition method, and their structures were characterized using electron microscopy. Cyclic voltammetry was used to qualitatively characterize the capacitive properties of the composite RuO<SUB>2</SUB>/PEDOT nanotubes. Their specific capacitance, energy density and power density were evaluated by galvanostatic charge/discharge cycles at various current densities. The pseudocapacitance behavior of these composite nanotubes originates from ion diffusion during the simultaneous and parallel redox processes of RuO<SUB>2</SUB> and PEDOT. We show that the energy density (specific capacitance) of PEDOT nanotubes can be remarkably enhanced by electrodepositing RuO<SUB>2</SUB> into their porous walls and onto their rough internal surfaces. The flexible PEDOT prevents the RuO<SUB>2</SUB> from breaking and detaching from the current collector while the rigid RuO<SUB>2</SUB> keeps the PEDOT nanotubes from collapsing and aggregating. The composite RuO<SUB>2</SUB>/PEDOT nanotube can reach a high power density of 20 kW kg<SUP>−1</SUP> while maintaining 80% energy density (28 Wh kg<SUP>−1</SUP>) of its maximum value. This high power capability is attributed to the fast charge/discharge of nanotubular structures: hollow nanotubes allow counter-ions to readily penetrate into the composite material and access their internal surfaces, while a thin wall provides a short diffusion distance to facilitate ion transport. The high energy density originates from the RuO<SUB>2</SUB>, which can store high electrical/electrochemical energy intrinsically. The high specific capacitance (1217 F g<SUP>−1</SUP>) which is contributed by the RuO<SUB>2</SUB> in the composite RuO<SUB>2</SUB>/PEDOT nanotube is realized because of the high specific surface area of the nanotubular structures. Such PEDOT/RuO<SUB>2</SUB> composite nanotube materials are an ideal candidate for the development of high-energy and high-power supercapacitors.</P> <P>Graphic Abstract</P><P>RuO<SUB>2</SUB>/poly(3,4-ethylenedioxythiophene) composite nanotubes with high specific capacitance and fast charging/discharging capability for high-energy and high-power supercapacitor applications are reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b918589p'> </P>

MnO₂/TiN heterogeneous nanostructure design for electrochemical energy storage

Sherrill, Stefanie A.,Duay, Jonathon,Gui, Zhe,Banerjee, Parag,Rubloff, Gary W.,Lee, Sang Bok Royal Society of Chemistry 2011 Physical chemistry chemical physics Vol.13 No.33

<P>MnO<SUB>2</SUB>/TiN nanotubes are fabricated using facile deposition techniques to maximize the surface area of the electroactive material for use in electrochemical capacitors. Atomic layer deposition is used to deposit conformal nanotubes within an anodic aluminium oxide template. After template removal, the inner and outer surfaces of the TiN nanotubes are exposed for electrochemical deposition of manganese oxide. Electron microscopy shows that the MnO<SUB>2</SUB> is deposited on both the inside and outside of TiN nanotubes, forming the MnO<SUB>2</SUB>/TiN nanotubes. Cyclic voltammetry and galvanostatic charge–discharge curves are used to characterize the electrochemical properties of the MnO<SUB>2</SUB>/TiN nanotubes. Due to the close proximity of MnO<SUB>2</SUB> with the highly conductive TiN as well as the overall high surface area, the nanotubes show very high specific capacitance (662 F g<SUP>−1</SUP> reported at 45 A g<SUP>−1</SUP>) as a supercapacitor electrode material. The highly conductive and mechanically stable TiN greatly enhances the flow of electrons to the MnO<SUB>2</SUB> material, while the high aspect ratio nanostructure of TiN creates a large surface area for short diffusion paths for cations thus improving high power. Combining the favourable structural, electrical and energy properties of MnO<SUB>2</SUB> and TiN into one system allows for a promising electrode material for supercapacitors.</P> <P>Graphic Abstract</P><P>Atomic layer deposition and electrochemical deposition are combined to fabricate MnO<SUB>2</SUB>/TiN heterogeneous nanostructures for electrochemical energy storage. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cp21815h'> </P>

Perceived Relevance of Grade 9 Mathematics Topics to Everyday Life : Inputs to Context-based Enrichment Activities

John Patrick S. Alcantara,John Christian E. Isip,Gerardo R. Sison, Jr.,Allan A. Yutoc,Butch Stephen C. Duay,Rexella M. Umoquit ASCONS 2020 IJASC Vol.2 No.2

Background/Objectives: This research aspires to develop context-based enrichment activities that will make an interrelation between the concepts taught in Grade 9 Mathematics in Angat National High School at Taboc, Angat, Bulacan to the lives of the students. Methods/Statistical analysis: The sample of the study included 35 students. Contextual Teaching and Learning (CTL) approach can be used to address this study. Using the survey questionnaires, results revealed the topics that has perceived low relevance to the students were, law of sine, law of cosine, angle of elevation and depression, quadratic inequalities, applications on quadratic function, equations transformable into quadratic equation, oblique triangles, trigonometric ratios and special angle, solving quadratic equations by completing the square and graphs of quadratic function, and these are the topics contained in the enrichment activities. Findings: The students also replied that there is a need to come up with an instructional material that will connect these concepts to their lives and to improve their knowledge, abilities and skills, to monitor their assimilation of information, and to contribute to their overall development and upbringing. Improvements/Applications: The evaluation of the instructors to the enrichment activities scored an admissible mark and was complimented as useful and applicable.