Unveiling the Role of DMAP for the Se-Catalyzed Oxidative Carbonylation of Alcohols: A Mechanism Study.

Considering the remarkable catalytic activity (160 times higher) of Se/DMAP for the oxidative carbonylation of alcohols, unveiling the role of DMAP in catalysis is highly required. We investigated DFT calculations, and the proposed intermediates were verified with in situ ATR-FTIR analysis. DFT showed that the formation of [DMAP···HSe]δ-[DMAP(CO)OR]δ+ (IV) via nucleophilic substitution of DMAP at the carbonyl group of DMAP···HSe(CO)OR is the most energetically favorable. DMAP acts as both a nucleophile and a hydrogen bond acceptor, which is responsible for its remarkable activity.

Synthesizing a Gel Polymer Electrolyte for Supercapacitors, Assembling a Supercapacitor Using a Coin Cell, and Measuring Gel Electrolyte Performance.

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.

Selective CO2 adsorption and bathochromic shift in a phosphocholine-based lipid and conjugated polymer assembly.

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 CO2 was responsible for 6 times more CO2 being adsorbed onto the assembly than N2, and that with repeated CO2 adsorption and vacuuming procedures, the assembly structures of the lipid-polymer assembly were irreversibly changed, as demonstrated by in situ grazing-incidence X-ray diffraction during the gas adsorption and desorption. Despite the disruption of the lipid structure caused by adsorbed polar gas molecules on polar head groups, gas adsorption could promote orderly alkyl chain packing by inducing compressive strain, resulting in enhanced electron delocalization of conjugated backbones and bathochromic light absorption. The findings suggest that merging the structures of the crystalline functional polymer and lipid bilayer is a viable option for solar energy-converting systems that use conjugated polymers as a light harvester and the polar heads as CO2-capturing sites.

Low-Crystalline AuCuIn Catalyst for Gaseous CO2 Electrolyzer.

Despite its importance for the establishment of a carbon-neutral society, the electrochemical reduction of CO2  to value-added products has not been commercialized yet because of its sluggish kinetics and low selectivity. The present work reports the fabrication of a low-crystalline trimetallic (AuCuIn) CO2  electroreduction catalyst and demonstrates its high performance in a gaseous CO2  electrolyzer. The high Faradaic efficiency (FE) of CO formation observed at a low overpotential in a half-cell test is ascribed to the controlled crystallinity and composition of this catalyst as well as to its faster charge transfer, downshifted d-band center, and low oxophilicity. The gaseous CO2  electrolyzer with the optimal catalyst as the cathode exhibits superior cell performance with a high CO FE and production rate, outperforming state-of-the-art analogs. Thus, the obtained results pave the way to the commercialization of CO2  electrolyzers and promote the establishment of a greener society.

Evaluating the Electrochemical Properties of Supercapacitors using the Three-Electrode System.

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.

Elaborate Control of Inkjet Printer for Fabrication of Chip-based Supercapacitors.

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.

Methodologies for Fabricating Flexible Supercapacitors.

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.

Myroides fluvii sp. nov., isolated from the Han River, Republic of Korea.

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).