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1.
Adv Sci (Weinh) ; 10(22): e2301248, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37211689

ABSTRACT

The effective spatial distribution and arrangement of electrochemically active and conductive components within metal oxide nanoparticle (MO NP)-based electrodes significantly impact their energy storage performance. Unfortunately, conventional electrode preparation processes have much difficulty addressing this issue. Herein, this work demonstrates that a unique nanoblending assembly based on favorable and direct interfacial interactions between high-energy MO NPs and interface-modified carbon nanoclusters (CNs) notably enhances the capacities and charge transfer kinetics of binder-free electrodes in lithium-ion batteries (LIBs). For this study, carboxylic acid (COOH)-functionalized carbon nanoclusters (CCNs) are consecutively assembled with bulky ligand-stabilized MO NPs through ligand-exchange-induced multidentate binding between the COOH groups of CCNs and the surface of NPs. This nanoblending assembly homogeneously distributes conductive CCNs within densely packed MO NP arrays without insulating organics (i.e., polymeric binders and/or ligands) and prevents the aggregation/segregation of electrode components, thus markedly reducing contact resistance between neighboring NPs. Furthermore, when these CCN-mediated MO NP electrodes are formed on highly porous fibril-type current collectors (FCCs) for LIB electrodes, they deliver outstanding areal performance, which can be further improved through simple multistacking. The findings provide a basis for better understanding the relationship between interfacial interaction/structures and charge transfer processes and for developing high-performance energy storage electrodes.

2.
Adv Sci (Weinh) ; 9(33): e2203800, 2022 11.
Article in English | MEDLINE | ID: mdl-36161719

ABSTRACT

Effective incorporation of conductive and energy storage materials into 3D porous textiles plays a pivotal role in developing and designing high-performance energy storage devices. Here, a fibril-type textile pseudocapacitor electrode with outstanding capacity, good rate capability, and excellent mechanical stability through controlled interfacial interaction-induced electroplating is reported. First, tetraoctylammonium bromide-stabilized copper sulfide nanoparticles (TOABr-CuS NPs) are uniformly assembled onto cotton textiles. This approach converts insulating textiles to conductive textiles preserving their intrinsically porous structure with an extremely large surface area. For the preparation of textile current collector with bulk metal-like electrical conductivity, Ni is additionally electroplated onto the CuS NP-assembled textiles (i.e., Ni-EPT). Furthermore, a pseudocapacitive NiCo-layered double hydroxide (LDH) layer is subsequently electroplated onto Ni-EPT for the cathode. The formed NiCo-LDH electroplated textiles (i.e., NiCo-EPT) exhibit a high areal capacitance of 12.2 F cm-2 (at 10 mA cm-2 ), good rate performance, and excellent cycling stability. Particularly, the areal capacity of NiCo-EPT can be further increased through their subsequent stacking. The 3-stack NiCo-EPT delivers an unprecedentedly high areal capacitance of 28.8 F cm-2 (at 30 mA cm-2 ), which outperforms those of textile-based pseudocapacitor electrodes reported to date.


Subject(s)
Electroplating , Nanoparticles , Electrodes , Textiles
3.
Adv Mater ; 32(51): e2001924, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32954530

ABSTRACT

Organic-ligand-based solution processes of metal and transition metal oxide (TMO) nanoparticles (NPs) have been widely studied for the preparation of electrode materials with desired electrical and electrochemical properties for various energy devices. However, the ligands adsorbed on NPs have a significant effect on the intrinsic properties of materials, thus influencing the performance of bulk electrodes assembled by NPs for energy devices. To resolve these critical drawbacks, numerous approaches have focused on developing unique surface chemistry that can exchange bulky ligands with small ligands or remove bulky ligands from NPs after NP deposition. In particular, recent studies have reported that the ligand-exchange-induced layer-by-layer (LE-LbL) assembly of NPs enables controlled assembly of NPs with the desired interparticle distance, and interfaces, dramatically improving the electrical/electrochemical performance of electrodes. This emerging approach also demonstrates that efficient surface ligand engineering can exploit the unique electrochemical properties of individual NPs and maximize the electrochemical performance of the resultant NP-assembled electrodes through improved charge transfer efficiency. This report focuses on how LE-LbL assembly can be effectively applied to NP-based energy storage/conversion electrodes. First, the basic principles of the LE-LbL approach are introduced and then recent progress on NP-based energy electrodes prepared via the LE-LbL approach is reviewed.

4.
Adv Mater ; 32(7): e1906460, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31830359

ABSTRACT

For the development of wearable electronics, the replacement of rigid, metallic components with fully elastomeric materials is crucial. However, current elastomeric electrodes suffer from low electrical conductivity and poor electrical stability. Herein, a metal-like conductive elastomer with exceptional electrical performance and stability is presented, which is used to fabricate fully elastomeric electronics. The key feature of this material is its wrinkled structure, which is induced by in situ cooperation of solvent swelling and densely packed nanoparticle assembly. Specifically, layer-by-layer assembly of metal nanoparticles and small-molecule linkers on elastomers generates the hierarchical wrinkled elastomer. The elastomer demonstrates remarkable electrical conductivity (170 000 and 11 000 S cm-1 at 0% and 100% strain, respectively), outperforming previously reported elastomeric electrodes based on nanomaterials. Furthermore, a fully elastomeric triboelectric nanogenerator based on wrinkled elastomeric electrode exhibits excellent electric power generation performance due to the compressible, large contact area of the wrinkled surface during periodic contact and separation.

5.
Nanoscale ; 11(38): 17815-17830, 2019 Oct 03.
Article in English | MEDLINE | ID: mdl-31552994

ABSTRACT

One of the most critical issues in electrochromic (EC) films based on transition metal oxides such as tungsten oxides (WOx) is their poor charge transfer property, which is closely related to EC performance. Herein, high-performance EC films with enhanced charge transport are prepared using small-molecule linkers and transparent/conductive nanoparticles (NPs). In this work, oleylamine (OAm)-stabilized WO2.72 nanorods (NRs) and OAm-stabilized indium tin oxide (ITO) NPs are layer-by-layer (LbL)-assembled with small-molecule linkers (tris(2-aminoethyl)amine, TREN) using a ligand-exchange reaction between bulky/insulating OAm ligands and TREN molecules. In this case, there is only one TREN layer between neighboring inorganic components (WO2.72 NRs and/or ITO NPs), resulting in a dramatic decrease in the separation distance. This minimized separation distance as well as the periodic insertion of transparent/conductive ITO NPs can significantly reduce the charge transfer resistance within WO2.72 NR-based EC films, which remarkably improves their EC performance. Compared to EC films without ITO NPs, the formed EC films with ITO NPs exhibit faster switching responses (4.1 times in coloration time and 3.5 times in bleaching time) and a maximum optical modulation of approximately 55.8%. These results suggest that electrochemical performance, including EC performance, can be significantly improved through structural/interfacial designing of nanocomposites.

6.
Nat Commun ; 9(1): 4479, 2018 10 26.
Article in English | MEDLINE | ID: mdl-30367069

ABSTRACT

Electrical communication between an enzyme and an electrode is one of the most important factors in determining the performance of biofuel cells. Here, we introduce a glucose oxidase-coated metallic cotton fiber-based hybrid biofuel cell with efficient electrical communication between the anodic enzyme and the conductive support. Gold nanoparticles are layer-by-layer assembled with small organic linkers onto cotton fibers to form metallic cotton fibers with extremely high conductivity (>2.1×104 S cm-1), and are used as an enzyme-free cathode as well as a conductive support for the enzymatic anode. For preparation of the anode, the glucose oxidase is sequentially layer-by-layer-assembled with the same linkers onto the metallic cotton fibers. The resulting biofuel cells exhibit a remarkable power density of 3.7 mW cm-2, significantly outperforming conventional biofuel cells. Our strategy to promote charge transfer through electrodes can provide an important tool to improve the performance of biofuel cells.


Subject(s)
Bioelectric Energy Sources , Cotton Fiber , Glucose Oxidase/chemistry , Gold/chemistry , Electric Conductivity , Electrodes , Glucose/metabolism , Glucose Oxidase/metabolism , Metal Nanoparticles/chemistry , Metal Nanoparticles/ultrastructure , Oxidation-Reduction
7.
Nat Commun ; 8(1): 536, 2017 09 14.
Article in English | MEDLINE | ID: mdl-28912562

ABSTRACT

The effective implantation of conductive and charge storage materials into flexible frames has been strongly demanded for the development of flexible supercapacitors. Here, we introduce metallic cellulose paper-based supercapacitor electrodes with excellent energy storage performance by minimizing the contact resistance between neighboring metal and/or metal oxide nanoparticles using an assembly approach, called ligand-mediated layer-by-layer assembly. This approach can convert the insulating paper to the highly porous metallic paper with large surface areas that can function as current collectors and nanoparticle reservoirs for supercapacitor electrodes. Moreover, we demonstrate that the alternating structure design of the metal and pseudocapacitive nanoparticles on the metallic papers can remarkably increase the areal capacitance and rate capability with a notable decrease in the internal resistance. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1 mW cm-2 and 267.3 µWh cm-2, respectively, substantially outperforming the performance of conventional paper or textile-type supercapacitors.With ligand-mediated layer-by-layer assembly between metal nanoparticles and small organic molecules, the authors prepare metallic paper electrodes for supercapacitors with high power and energy densities. This approach could be extended to various electrodes for portable/wearable electronics.

8.
J Am Chem Soc ; 136(49): 17213-23, 2014 Dec 10.
Article in English | MEDLINE | ID: mdl-25386672

ABSTRACT

We introduce a general and versatile methodology that allows a facile incorporation of the functional components with completely different chemistry of hydrophilic/hydrophobic properties within nanocomposite films, and furthermore combine a number of the distinctive advantages of traditional electrostatic layer-by-layer (LbL) assembly in aqueous media and covalent LbL assembly in nonpolar media. Our approach, amphiphilic LbL assembly, is based on the high affinity between sulfonic (or phosphonic) acid-functionalized materials in aqueous media and hydrophobic metal oxide (or metal) NPs stabilized by oleic acid (OA) in nonpolar solvent. For demonstrating the effectiveness of our approach, we show that amphiphilic LbL assembly can be easily applied to the preparation of functional colloid materials allowing the reversible phase transfer between aqueous and nonpolar media, and supercapacitor electrodes with high volumetric capacitance (280 F·cm(-3) at 10 mV·s(-1)) using reduced graphene oxide with sulfonic acid moieties and well-defined OA-Fe3O4 NPs.

9.
Nanoscale ; 6(16): 9655-64, 2014 Aug 21.
Article in English | MEDLINE | ID: mdl-24990386

ABSTRACT

In this study, we report on the fabrication of high performance planar-type flexible micro-supercapacitor (MSC) arrays using Au electrodes coated with a functionalized multi-walled carbon nanotube (MWNT) film and a layer of MWNT-COOH/MnOx nanoparticle (NP) composite on top. The MWNT thin film was formed via layer-by-layer (LbL) assembly of MWNTs functionalized with amine groups and MWNTs with carboxylic acid groups in water. The hydrothermally synthesized composite of MWNT-COOH/MnOx NPs was coated on top of the MWNT film (LbL-MWNT). The addition of MWNT-COOH/MnOx NP composite as a top layer enhanced the performance of the MSCs dramatically, resulting in a volumetric capacitance of 50 F cm(-3) at a scan rate of 10 mV s(-1) and a coulombic efficiency of ∼100%. By contrast, a volumetric capacitance of 3.6 F cm(-3) was obtained when using only the LbL-MWNT film. After repetitive operation up to ∼10(4) times, the capacitance remained at ∼88.3% of the original value. With a deliberate circuit design consisting of serially connected MSC arrays, various light-emitting diodes operating at different bias voltages could be lit. The MSC circuit fabricated on a polyethylene terephthalate (PET) film showed stable electrochemical properties upon 1000 cycles of bending deformation.

10.
Small ; 9(22): 3784-91, 2013 Nov 25.
Article in English | MEDLINE | ID: mdl-23666682

ABSTRACT

Organic field-effect transistor (OFET) memory devices made using highly stable iron-storage protein nanoparticle (NP) multilayers and pentacene semiconductor materials are introduced. These transistor memory devices have nonvolatile memory properties that cause reversible shifts in the threshold voltage (Vth ) as a result of charge trapping and detrapping in the protein NP (i.e., the ferritin NP with a ferrihydrite phosphate core) gate dielectric layers rather than the metallic NP layers employed in conventional OFET memory devices. The protein NP-based OFET memory devices exhibit good programmable memory properties, namely, large memory window ΔVth (greater than 20 V), a fast switching speed (10 µs), high ON/OFF current ratio (above 10(4)), and good electrical reliability. The memory performance of the devices is significantly enhanced by molecular-level manipulation of the protein NP layers, and various biomaterials with heme Fe(III) /Fe(II) redox couples similar to a ferrihydrite phosphate core are also employed as charge storage dielectrics. Furthermore, when these protein NP multilayers are deposited onto poly(ethylene naphthalate) substrates coated with an indium tin oxide gate electrode and a 50-nm-thick high-k Al2 O3 gate dielectric layer, the approach is effectively extended to flexible protein transistor memory devices that have good electrical performance within a range of low operating voltages (<10 V) and reliable mechanical bending stability.

11.
ACS Nano ; 7(1): 143-53, 2013 Jan 22.
Article in English | MEDLINE | ID: mdl-23214437

ABSTRACT

A robust method for preparing nanocomposite multilayers was developed to facilitate the assembly of well-defined hydrophobic nanoparticles (i.e., metal and transition metal oxide NPs) with a wide range of functionalities. The resulting multilayers were stable in both organic and aqueous media and were characterized by a high NP packing density. For example, inorganic NPs (including Ag, Au, Pd, Fe3O4, MnO2) dispersed in organic media [corrected]were shown to undergo layer-by-layer assembly with amine-functionalized polymers to form nanocomposite multilayers while incurring minimal physical and chemical degradation of the inorganic NPs. In addition, the nanocomposite multilayer films formed onto flat and colloidal substrates could directly induce the adsorption of the electrostatically charged layers without the need for additional surface treatments. This approach is applicable to the preparation of electronic film devices, such as nonvolatile memory devices requiring a high memory performance (ON/OFF current ratio >10(3) and good memory stability).


Subject(s)
Computer Storage Devices , Inorganic Chemicals/chemistry , Membranes, Artificial , Nanostructures/chemistry , Nanostructures/ultrastructure , Equipment Design , Equipment Failure Analysis , Hydrophobic and Hydrophilic Interactions , Ligands , Materials Testing , Particle Size
12.
ACS Nano ; 5(12): 9918-26, 2011 Dec 27.
Article in English | MEDLINE | ID: mdl-22092235

ABSTRACT

Electrochemical properties of redox proteins, which can cause the reversible changes in the resistance according to their redox reactions in solution, are of the fundamental and practical importance in bioelectrochemical applications. These redox properties often depend on the chemical activity of transition metal ions as cofactors within the active sites of proteins. Here, we demonstrate for the first time that the reversible resistance changes in dried protein films based on ferritin nanoparticles can be caused by the externally applied voltage as a result of charge trap/release of Fe(III)/Fe(II) redox couples. We also show that one ferritin nanoparticle of about 12 nm size can be operated as a nanoscale-memory device, and furthermore the layer-by-layer assembled protein multilayer devices can be extended to bioinspired electronics with adjustable memory performance via molecular level manipulation.


Subject(s)
Ferritins/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Electric Conductivity , Materials Testing , Particle Size , Protein Binding , Surface Properties
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