Search

Porous metal or metal oxide frameworks have been comprehensively applicated to numerous fields such as catalyst, energy storage system, and bio-filtration. Here, we introduce a de-alloying method prior to a facile polymer gel-templating to synthesize a self-supporting porous metal/metal oxide frameworks (e.g. Au, Ag, Ag/CuO, Au/MnO2, etc.). The template methods based on polymer gel suggest easy preparation of porous metal/metal oxide frameworks, prepared by heating a metal precursor impregnated in polymer gel. Compared to de-alloying Ag65A35 method, polymer gel based soft template serves numerous advantages as follows; 1) facile fabrication of porous transition metal structure, 2) atom economy, 3) high-loading of precious metals, 4) harmless to human and environment, 5) natural abundance, 6) easy to scale-up and control the pore size by differentiate the polymer content ratio, 7) mild reaction conditions, and 8) structural controllability, 9) cost-effectiveness, etc. We report the methodologies to synthesis bicontinuous metal/ metal oxide architectures, derived from porous gel soft templates, and they are applicated to the energy storage system such as, supercapacitor, pseudocapacitor, and battery.

Assembly films of a phosphocholine-based lipid and a crystalline conjugated polymer had significant CO2 selective adsorption and light absorption due to the attractive interaction of CO2 with exposed polar lipid heads and enhanced morphologies.

Supercapacitors (SC) have attracted attention as energy storage devices due to their high density and long cycle performance. SCs used in devices operating in stretchable systems require stretchable electrolytes. Gel polymer electrolytes (GPEs) are an ideal replacement for liquid electrolytes. Polyvinyl alcohol (PVA) and polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) have been widely applied as a polymer-matrix-based electrolytes for supercapacitors because of their low cost, chemically stable, wide operating temperature range, and high ionic conductivities. Herein, we describe the procedures for (1) synthesizing a gel polymer electrolyte with PVA and PVDF-HFP, (2) measuring the electrochemical stability of the gel polymer electrolytes by cyclic voltammetry (CV), (3) measuring the ionic conductivity of the gel polymer electrolytes by electrochemical impedance spectroscopy (EIS), (4) assembling symmetric coin cells using activated carbon (AC) electrodes with the PVA- and PVDF-HFP-based gel polymer electrolytes, and (5) evaluating the electrochemical performance using galvanostatic charge-discharge analysis (GCD) and CV at 25 °C. Additionally, we describe the challenges and insights gained from these experiments.

In this study, intermolecular interactions were investigated for increasing the charge carrier mobility of organic field-effect transistors (OFETs) based on a conjugated polymer. A diketopyrrolopyrrole (DPP)-based conjugated polymer widely used in OFETs, i.e., poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (PDPP-DTT), was assembled using 2-bromobenzaldehyde (2-BBA) and used as an active layer for OFETs. Morphological characterization and analysis for non-covalent intermolecular interactions suggested that the halogen bonding between the bromide of 2-BBA and electron-donor group of PDPP-DTT and the association between the electron-acceptor group in 2-BBA and sulfur of PDPP-DTT improved the hole transfer in the PDPP-DTT-based OFETs. The intermolecular interactions resulting from the addition of 2-BBA contributed to the two-fold enhancement of the hole mobility, two-order increase in magnitude of the current on/off ratio, and 50% decrease in the threshold voltage of the OFETs based on PDPP-DPP.

Manufacturing supercapacitors by printing enables reduced material waste, easy customization, adaptability of form factor with the application, and high compatibility with other printed electronics...

The three-electrode system is a basic and general analytical platform for investigating the electrochemical performance and characteristics of energy storage systems at the material level. Supercapacitors are one of the most important emergent energy storage systems developed in the past decade. Here, the electrochemical performance of a supercapacitor was evaluated using a three-electrode system with a potentiostat device. The three-electrode system consisted of a working electrode (WE), reference electrode (RE), and counter electrode (CE). The WE is the electrode where the potential is controlled and the current is measured, and it is the target of research. The RE acts as a reference for measuring and controlling the potential of the system, and the CE is used to complete the closed circuit to enable electrochemical measurements. This system provides accurate analytical results for evaluating electrochemical parameters such as the specific capacitance, stability, and impedance through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Several experimental design protocols are proposed by controlling the parameter values of the sequence when using a three-electrode system with a potentiostat device to evaluate the electrochemical performance of supercapacitors. Through these protocols, the researcher can set up a three-electrode system to obtain reasonable electrochemical results for assessing the performance of supercapacitors.

We assemble a film of a phosphocholine-based lipid and a crystalline conjugated polymer using hydrophobic interactions between the alkyl tails of the lipid and alkyl side chains of the polymer, and demonstrated its selective gas adsorption properties and the polymer's improved light absorption properties. We show that a strong attractive interaction between the polar lipid heads and CO

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage devices. To get high-quality products, however, sophisticated operation skills are required depending on the physical properties of the ink materials. In this regard, optimizing the inkjet printing parameters is as important as developing the physical properties of the ink materials. In this study, optimization of the inkjet printing software parameters is presented for fabricating a supercapacitor. Supercapacitors are attractive energy storage systems because of their high power density, long lifespan, and various applications as power sources. Supercapacitors can be used in the Internet of Things (IoT), smartphones, wearable devices, electrical vehicles (EVs), large energy storage systems, etc. The wide range of applications demands a new method that can fabricate devices in various scales. The inkjet printing method can break through the conventional fixed-size fabrication method.

Despite its importance for the establishment of a carbon-neutral society, the electrochemical reduction of CO

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.

A Gram-stain-negative, aerobic, short rod-shaped, pale yellow-pigmented, non-motile and gentamycin-resistant bacterial strain designated CJ210T was isolated from the Han River, Republic of Korea. Strain CJ210T grew optimally at 30 °C and pH 7.0 in the absence of NaCl on tryptic soy agar. Flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain CJ210T belonged to the genus Myroides within the family Flavobacteriaceae and was most closely related to Myroides odoratus KACC 14347T (98.1 % similarity), followed by M. injenensis KCTC 23367T (95.3 % similarity). The average nucleotide identity values between strain CJ210T and two closely related type strains M. odoratus KACC 14347T and M. injenensis KCTC 23367T were 83.7 and 73.8 %, respectively. The digital DNA–DNA hybridization results between strain CJ210T and the related type strains were 27.5 and 20.2 %, respectively. Strain CJ210T contained menaquinone 6 (MK-6) as the predominant menaquinone. The predominant polar lipids were phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids. The major fatty acids of strain CJ210T were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 9 (comprising iso-C17 : 1 ω9c and/or C16 : 0 10-methyl). Whole genome sequencing revealed that strain CJ210T had a genome of 3.8 Mbp with 36.5 % DNA G+C content. The genome contained several antimicrobial resistance genes including an aminoglycoside-resistant gene. On the basis of the polyphasic taxonomic study, strain CJ210T represents a novel species in the genus Myroides , for which name Myrodies fluvii sp. nov. is proposed. The type strain is CJ210T (=KACC 19954T=JCM 33306T).

The spread of wearable and flexible electronics devices has been accelerating in recent years for a wide range of applications. Development of an appropriate flexible power source to operate these flexible devices is a key challenge. Supercapacitors are attractive for powering portable lightweight consumer devices due to their long cycle stability, fast charge-discharge cycle, outstanding power density, wide operating temperatures and safety. Much effort has been devoted to ensure high mechanical and electrochemical stability upon bending, folding or stretching and to develop flexible electrodes, substrates and overall geometrically-flexible structures. Supercapacitors have attracted considerable attention and shown many applications on various scales. In this review, we focus on flexible structural design under six categories: paper-like, textile-like, wire-like, origami, biomimetics based design and micro-supercapacitors. Finally, we present our perspective of flexible supercapacitors and emphasize current technical difficulties to stimulate further research.

Metal-containing porous structures have been widely used in the fields of electrochemical and acid-base catalysis, bio-filtration, and heat-dissipation. Here, we propose a method for the fabrication of robust macroporous metallic sponges using agarose gel and HAuCl4 as soft-sacrificial templates and Au precursor, respectively. We demonstrate that the preparation of self-supporting macroporous Au sponges is practicable by heating the soft-agarose framework in the range of temperatures from 200 to 500°C. Before the calcination of agarose framework, Au precursor was reduced using NaBH4. A series of data obtained from X-ray photoelectron spectroscopy and X-ray diffraction indicates that the Au sponges were well synthesized with high crystallinity. The structural properties of porous Au were methodically investigated using Rietveld refinement and density-functional-theory calculations. The use of agarose gel as a soft template for the fabrication of metallic sponges has various advantages over conventional methods, as this approach is environmentally benign, shape-controllable, inexpensive, and scalable for mass production.

Coffee is one of the largest agricultural products generally used in beverages. The international production of coffee is approximately 120 billion bags per year (60 kg per bag) from the International Coffee Organization. It corresponds to an annual production of approximately 8 million metric tons of coffee; therefore, coffee can be considered as a significant agricultural commodity. However, the majority of the produced coffee is disposed of waste sludge by beverage manufacturers. Herein, we report the use of graphitic porous carbon materials that have been derived from waste coffee sludge for developing an energy storage electrode based on a hydrothermal recycling procedure. Waste coffee sludge is used as a carbonaceous precursor for energy storage due to its lower cost, greater abundance, and easier availability as compared to other carbon resources. In addition, excluding the oil components, coffee sludge is mainly composed of cellulose-based materials with many heteroatoms (e.g., nitrogen, oxygen, and sulfur). It is considered good precursors for the fabrication of functionalized carbon materials. The unique graphite porous carbon production by hydrothermal carbonization of coffee sludge is particularly attractive as it addresses waste handling issues, offers a cheaper recycling method, and reduces the requirement for landfills. Therefore, we recycled the coffee slurry into hydrated carbon via sequential hydrothermal carbonization (HTC) as an activation process. The HTC reaction converts the cellulose-based biomass into hydrochar, bio-liquid, and gas at a relatively low temperature range (180°C~230°C). Hydrochar has various surface functional groups; so, it has been investigated for alternative fuels, carbon dioxide sequestration, and heavy metal immobilization for environmental remediation. During sequential hydrothermal activation, a porous and graphitic structure of the hydrochar can be developed, where these features are the most important characteristics of materials for electron accumulation. The porous and graphitic property of carbonaceous materials promotes electron accumulation for capacitive reactions. The electrical double-layer capacitive (EDLC) reaction has attracted considerable interest for next-generation energy storage systems such as supercapacitors. Our investigations revealed that the graphitic porous carbon, which is derived from spent coffee sludge, was employed in EDLCs by manipulating its unique microstructure which has a high hierarchical porous nature and graphitic edges. To activate the synthesized material, the dried hydrochar was mixed with 1 M KOH at a mass ratio of 1:3.5. The mixed sample was also heated at 700°C for 2 h in the hydrothermal reactor. After that, the activated hydrochar (AHC) was washed with pure water until a pH value of 7 was reached; subsequently, it was dried in an oven at 105°C for 24 h. After activation process, to gain deeper insights into the microstructure of HC and AHC regarding the specific surface area and pore size distribution, N2 adsorption/desorption isotherms were conducted. In Figure c, the TEM image of AHC has graphitized structure, which indicates easy pathways for ion and electron transport. AHC provides a higher electrochemical performance as an EDLC electrode than that demonstrated by the HC because of the high surface area (~1067 m2 g−1) and a hierarchical multi-porous structure of AHC as shown in Figure d. In addition, the conductivity of AHC is superior to that of HC; that is expected because AHC has a connected graphitized structure, which is not observed for HC, as confirmed by the TEM data (Figure a-c). The tangent to the curve in the low frequency region for AHC is higher than that for HC in Figure f. This indicates AHC has a better ion propagation and more ideal supercapacitive performance than HC. Figure a-c show the morphological differences due to the activation reaction, suggesting the existence of a well-developed hierarchical porous structure in AHC as compared to that the structure of HC. When the porous electrode is dipped into the electrolyte, the interconnections between the macropores not only provide sites for localization of the electrolyte, but also form pathways. The specific capacitance of the AHC based supercapacitors was 140 F g-1 in Figure e. Also, it demonstrated a good cyclic performance with 3% reduction over 1500 cycles at current density of 0.3 A g-1. Thus, AHC from waste coffee sludge could be an environmentally friendly technique associated with energy storage systems. This research was funded and conducted under the Competency Development Program for Industry Specialists of the Korean MOTIE, operated by KIAT (No. P0012453, Next-generation Display Expert Training Project for Innovation Process and Equipment, Materials Engineers). Figure 1