Nanotubular metal-insulator-metal capacitor arrays for energy storage

Banerjee, Parag,Perez, Israel,Henn-Lecordier, Laurent,Lee, Sang Bok,Rubloff, Gary W. Springer Science and Business Media LLC 2009 Nature nanotechnology Vol.4 No.5

<P>Nanostructured devices have the potential to serve as the basis for next-generation energy systems that make use of densely packed interfaces and thin films. One approach to making such devices is to build multilayer structures of large area inside the open volume of a nanostructured template. Here, we report the use of atomic layer deposition to fabricate arrays of metal-insulator-metal nanocapacitors in anodic aluminium oxide nanopores. These highly regular arrays have a capacitance per unit planar area of approximately 10 microF cm-2 for 1-microm-thick anodic aluminium oxide and approximately 100 microF cm-2 for 10-microm-thick anodic aluminium oxide, significantly exceeding previously reported values for metal-insulator-metal capacitors in porous templates. It should be possible to scale devices fabricated with this approach to make viable energy storage systems that provide both high energy density and high power density.</P>

Structural, electrical, and optical properties of atomic layer deposition Al-doped ZnO films

Banerjee, Parag,Lee, Won-Jae,Bae, Ki-Ryeol,Lee, Sang Bok,Rubloff, Gary W. American Institute of Physics 2010 JOURNAL OF APPLIED PHYSICS - Vol.108 No.4

Electrical conductivity of p-type BiOCl nanosheets

Myung, Yoon,Wu, Fei,Banerjee, Sriya,Park, Jeunghee,Banerjee, Parag The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.13

<P>High quality BiOCl nanosheets were fabricated using facile, room temperature hydrolysis of Bi(NO<SUB>3</SUB>)<SUB>3</SUB> and HCl. The resulting nanosheets had dimensions of 500 nm with the exposed {001} facet. The band gap of the nanosheets was found to be 3.34 eV with conduction and valence band edges at −3.63 eV and −6.97 eV with respect to vacuum, respectively. The electrical conductivity of drop-cast BiOCl nanosheets was measured between aluminum patterned electrodes as a function of temperature and oxygen partial pressure (pO<SUB>2</SUB>). The activation energy for conduction in BiOCl was found to be 862 meV in the temperature range of 300–425 K and below 1000 mbar. The electrical conductivity varied with pO<SUB>2</SUB>, indicating <I>σ</I>∝ pO<SUB>2</SUB><SUP>1/4.05</SUP> and <I>σ</I>∝ pO<SUB>2</SUB><SUP>1/32</SUP> for low and sub atmospheric pressures, respectively. A prototypical device for low temperature (425 K) O<SUB>2</SUB> sensing was demonstrated.</P> <P>Graphic Abstract</P><P>BiOCl nanosheets were synthesized using a facile hydrolysis method and their p-type electrical conduction as a function of oxygen partial pressure was measured. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc09295c'> </P>

High to ultra-high power electrical energy storage

Sherrill, Stefanie A.,Banerjee, Parag,Rubloff, Gary W.,Lee, Sang Bok Royal Society of Chemistry 2011 Physical chemistry chemical physics Vol.13 No.46

<P>High power electrical energy storage systems are becoming critical devices for advanced energy storage technology. This is true in part due to their high rate capabilities and moderate energy densities which allow them to capture power efficiently from evanescent, renewable energy sources. High power systems include both electrochemical capacitors and electrostatic capacitors. These devices have fast charging and discharging rates, supplying energy within seconds or less. Recent research has focused on increasing power and energy density of the devices using advanced materials and novel architectural design. An increase in understanding of structure-property relationships in nanomaterials and interfaces and the ability to control nanostructures precisely has led to an immense improvement in the performance characteristics of these devices. In this review, we discuss the recent advances for both electrochemical and electrostatic capacitors as high power electrical energy storage systems, and propose directions and challenges for the future. We asses the opportunities in nanostructure-based high power electrical energy storage devices and include electrochemical and electrostatic capacitors for their potential to open the door to a new regime of power energy.</P> <P>Graphic Abstract</P><P>This article reviews recent advancements in electrochemical and electrostatic capacitors for high power energy storage with a focus on nanostructures and materials. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cp22659b'> </P>

Profile Evolution for Conformal Atomic Layer Deposition over Nanotopography

Cleveland, Erin R.,Banerjee, Parag,Perez, Israel,Lee, Sang Bok,Rubloff, Gary W. American Chemical Society 2010 ACS NANO Vol.4 No.8

<P>The self-limiting reactions which distinguish atomic layer deposition (ALD) provide ultrathin film deposition with superb conformality over the most challenging topography. This work addresses how the shapes (<I>i.e.</I>, surface profiles) of nanostructures are modified by the conformality of ALD. As a nanostructure template, we employ a highly scalloped surface formed during the first anodization of the porous anodic alumina (PAA) process, followed by removal of the alumina to expose a scalloped Al surface. SEM and AFM reveal evolution of surface profiles that change with ALD layer thickness, influenced by the way ALD conformality decorates the underlying topography. The evolution of surface profiles is modeled using a simple geometric 3D extrusion model, which replicates the measured complex surface topography. Excellent agreement is obtained between experimental data and the results from this model, suggesting that for this ALD system conformality is very high even on highly structured, sharp features of the initial template surface. Through modeling and experimentation, the benefits of ALD to manipulate complex surface topographies are recognized and will play an important role in the design and nanofabrication of next generation devices with increasingly high aspect ratios as well as nanoscale features.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-8/nn1009984/production/images/medium/nn-2010-009984_0009.gif'></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>

Cationically Substituted Bi_0.7Fe_0.3OCl Nanosheets as Li Ion Battery Anodes

Myung, Yoon,Choi, Jaewon,Wu, Fei,Banerjee, Sriya,Majzoub, Eric H.,Jin, Jaewon,Son, Seung Uk,Braun, Paul V.,Banerjee, Parag American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.16

<P>Cation substitutiob, of Bif(3+) with Fe3+ in BiOCl leads to the formation of tonically layered Bi0.7Fe0.3OCl nanosheets. The synthesis follows a hydrolysis route using bismuth(III) nitrate and iron(III) chloridejollowed by postannealing at 500 degrees C. Room temperature electrical conductivity improves from 6.11 X 10(-8) Sim for BiOCl tb 6.80 X 10(-7) S/m for Bi0.7Fe0.3OCl. Correspondingly, the activation energy for electriCal conduction reduces from 862 meV for pure BiOCI to 310 meV for Bi0.7Fe0.3OCl. These data suggest improved charge Mobility in Bi0.7Fe0.3OCl nanosheets. Density functional :theory calculations confirm this behavior by predicting a high density of states hear the Fermi level for Bi0.7Fe0.3OCl, The improvement in electrical conductivity is exploited in the electrochemical performance of Bi0.7Fe0.3OCl nanosheets. The insertion capacity of Li+ ions shows an increase of 2.5X, I from 215 mAh.g(-1) for undoped BiOCl to 542 mAh-g(-1) for Bi0.7Fe0.3OCl after 50 cycles at a current density of 50 mA g(-1). Thus, the direct substitution of Bi3+ sites with Fe3+ in BiOCI results in nanosheets of an tonically layered ternary semiconductor compound which is attractive for Li ion battery anode applications.</P>

BiOCl 음극의 Na 이온 저장 메커니즘 연구

명윤,김연주,나찬웅,권아람,김용환,Prasit Kumar Dutta,Sagar Mitra,Parag Banerjee 한국표면공학회 2019 한국표면공학회 학술발표회 초록집 Vol.2019 No.5

Mechanism of Na-Ion Storage in BiOCl Anode and the Sodium-Ion Battery Formation

Dutta, Prasit Kumar,Myung, Yoon,Kulangaramadom Venkiteswaran, Rohini,Mehdi, Layla,Browning, Nigel,Banerjee, Parag,Mitra, Sagar American Chemical Society 2019 The Journal of Physical Chemistry Part C Vol. No.

<P>We systematically unravel the mechanism by which sodium ion reacts electrochemically with ionically layered BiOCl nanosheets. Solution-processed BiOCl nanosheets were cycled using slow scan cyclic voltammetry (50 μV s<SUP>-1</SUP>) to reach the desired reaction voltages. Characterizations using in situ impedance spectroscopy and ex situ X-ray diffraction, Raman spectroscopy, and transmission electron microscopy are used to map the mechanism of Na-ion insertion and deinsertion in BiOCl nanosheets. It was found that BiOCl initially undergoes a conversion reaction to form metallic Bi. The metallic Bi further alloys with sodium ion to form Na<SUB>3</SUB>Bi and NaBi, a compound whose formation has not been reported before. We also detect the formation of BiO, Na<SUB>3</SUB>BiO<SUB>4</SUB>, and NaBiO<SUB>3</SUB>. Finally, BiOCl is used as anode against a Prussian blue cathode to prepare a full cell that is capable of providing an average discharge potential of ∼2.2 V at the 100th cycle. The overall study reveals new insights and key differences in the mechanism of sodium-based electrochemical energy storage systems.</P> [FIG OMISSION]</BR>

Surface Engineered CuO Nanowires with ZnO Islands for CO₂ Photoreduction

Wang, Wei-Ning,Wu, Fei,Myung, Yoon,Niedzwiedzki, Dariusz M.,Im, Hyung Soon,Park, Jeunghee,Banerjee, Parag,Biswas, Pratim American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.10

<P>Large arrays of massively parallel (10<SUP>8</SUP> cm<SUP>–2</SUP>) CuO nanowires were surface engineered with dense ZnO islands using a few pulsed cycles of atomic layer deposition (ALD). These nanowires were subjected to UV–vis radiation-based CO<SUB>2</SUB> photoreduction under saturated humidity (CO<SUB>2</SUB> + H<SUB>2</SUB>O mixture) conditions. We monitored CO<SUB>2</SUB> to CO conversion, indicating the viability of these nanostructures as potential photocatalysts. High-resolution transmission electron microscopy and atomic force microscopy indicated an island growth mechanism of ZnO epitaxially depositing on pristine, single crystal CuO nanowire surface. Photoluminescence and transient absorption spectroscopy showed a very high density of defects on these ZnO islands which trapped electrons and enhanced their lifetimes. Peak CO conversion (1.98 mmol/g-cat/hr) and quantum efficiency (0.0035%) were observed in our setup when the ZnO islands impinged each other at 1.4 nm (8 cycles of ALD) diameter; at which point ZnO island perimeter lengths maximized as well. A mechanism whereby simultaneous H<SUB>2</SUB>O oxidation and CO<SUB>2</SUB> reduction occurred in the active perimeter region between CuO nanowire and ZnO islands is proposed to explain the observed photoconversion of CO<SUB>2</SUB> to CO.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-10/am508590j/production/images/medium/am-2014-08590j_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am508590j'>ACS Electronic Supporting Info</A></P>