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Ligands can control the surface chemistry, physicochemical properties, processing, and applications of nanomaterials. MXenes are the fastest growing family of two-dimensional (2D) nanomaterials, showing promise for energy, electronic, and environmental applications. However, complex oxidation states, surface terminal groups, and interaction with the environment have hindered the development of organic ligands suitable for MXenes. Here, we demonstrate a simple, fast, scalable, and universally applicable ligand chemistry for MXenes using alkylated 3,4-dihydroxy-l-phenylalanine (ADOPA). Due to the strong hydrogen-bonding and π-electron interactions between the catechol head and surface terminal groups of MXenes and the presence of a hydrophobic fluorinated alkyl tail compatible with organic solvents, the ADOPA ligands functionalize MXene surfaces under mild reaction conditions without sacrificing their properties. Stable colloidal solutions and highly concentrated liquid crystals of various MXenes, including Ti

The etiology of Alzheimer’s disease (AD) is still unknown because of its complicated nature associated with various pathological components, including free radicals, acetylcholinesterase, and metal-free and metal-bound amyloid-beta. Thus, chemical reagents with modulating reactivities against multiple pathogenic factors are necessary for advancing our understanding of the complex pathogenesis. Here we report rational strategies for developing flavonoids that can control multiple pathological elements found in the brains of AD patients. Our investigations employing a series of flavonoids illuminated structural features critical for regulatory reactivities against desired targets. Moreover, the most promising flavonoid with multiple functions was developed based on our complete structure–activity relationship. Mechanistic studies confirmed that such versatile reactivities of the flavonoid are achieved by its redox potential and direct interactions with pathogenic factors. Overall, our studies demonstrate the feasibility of devising small molecules as multifunctional chemical reagents against pathological features found in AD.

Limited light absorption beyond the UV region and rapid photocarrier recombination are critical impediments for the improved photocatalytic performance of carbon quantum dots (CQDs) under visible-light irradiation. Herein, we demonstrate single-step microwave-assisted syntheses of O-CQDs (typical CQDs terminated by carboxylic and hydroxyl functional groups) from a sucrose precursor and Cl-doped CQDs (Cl-CQDs) from a sucralose precursor in short reaction times and without using obligatory strong acids for Cl doping. The doping of Cl into the CQDs is observed to widen the absorption range and facilitate an enhanced separation of photoexcited charge carriers, which is confirmed by the results of optical absorption, photothermal response, and pump-probe ultrafast transient absorption spectroscopy measurements of the O-CQDs and Cl-CQDs. The photoexcited charge carriers with their longer lifetimes in Cl-CQDs enabled the quick degradation of methylene blue dye, rapid conversion of Ag+ ions to metallic Ag nanoparticles on the CQD surfaces, and reduction of GO to a well-dispersed rGO through the photoelectron transfer reactions under visible-light irradiation. The facile Cl doping strategy, hybridization of Ag nanoparticles or rGO to CQDs, and the elevated charge separation mechanism would open up new avenues in designing CQD-based materials for futuristic applications.

Numerous wearable devices were developed to measure bioelectric signals for continuous healthcare monitoring. The electrode, which interconnects electronics and the human body, significantly affect...

Low-temperature fabrication of thin-film dielectrics is essential for various applications including flexible/stretchable electronics, monolithic three-dimensional integrated circuits, and large-ar...

We report a highly improved cathode catalyst by doping fluorine anions in oxygen sites of Ruddlesden-Popper material for CO2 electrolysis to produce CO in solid oxide electrolysis cells (SOECs). Th...

Herein, we demonstrate the ultraviolet (UV) light activated high-performance room-temperature NO gas sensor based on nitrogen-doped graphene quantum dots (NGQDs)-decorated TiO2 hybrid structure. Ti...

A Cu–Co–P electrocatalyst for hydrogen evolution reaction (HER) was designed with a dendritic and porous foam structure. Fabricated by one-step electrodeposition with binary alloy on a hydrogen bub...

Guest–host hydrogen bonding strongly affects the physical properties of clathrate hydrate, such as the thermodynamic stability, water dynamics, and dielectric properties, but attempts to quantify the effects of hydrogen bonding on these properties are rare thus far. As a preliminary work, this study investigates methane clathrate hydrates with three diazine isomers, pyrazine, pyrimidine, and pyridazine, which expect nearly the same van der Waals volumes due to their similar molecular shapes and sizes, and their guest–host hydrogen-bonding behaviors. The crystal structures of all three binary diazine + CH4 hydrate phases were identified as a cubic Fd3m structure, including diazine molecules in the 51264 cavity, commonly termed as structure II hydrate, by a high-resolution powder diffraction pattern analysis. The phase equilibrium curves of their clathrate hydrates were obtained by the P–T trajectory of the hydrate formation and dissociation process, and the thermodynamic stability trend was well-explained...

The unexpected formation of gas hydrates during production and transportation processes in petroleum industries is known as a serious problem. To deal with this problem, the oil and gas industry has been searching for hydrate inhibitors that have great performance and cost effectiveness. Recently, ionic liquids (ILs) have been suggested as novel hydrate inhibitors that are able to act in both thermodynamic and kinetic ways (so-called dual-function inhibitors). In this paper, we suggest a non-ionic liquid compound, morpholine, as a dual-function inhibitor by measuring hydrate-phase equilibria and a series of microscopic analyses [powder X-ray diffraction, solid-state 13C nuclear magnetic resonance (NMR), and Raman spectroscopy]. Moreover, the formation kinetics of gas hydrates in the presence of morpholine was found to be better than two comparators, 1-ethyl-3-methylimidazolium tetrafluoroborate and polyvinylpyrrolidone. Such inhibition effects of morpholine are thought to be mainly attributed to the nucle...

Diethylamine and n-propylamine, known as semiclathrate hydrate formers, are found to show structural transition when a help gas, CH4, was introduced. The diethylamine·8.67H2O semiclathrate hydrates (orthorhombic Pbcn) were changed to sH type (hexagonal P6/mmm) true clathrate hydrates, while the n-propylamine·6.5H2O semiclathrate hydrates (monoclinic P21/n) turned into sII clathrate hydrates (cubic Fd3m). Irregularly distorted voids in the semiclathrate hydrate phases were transformed to conventional ones after changing their structures to gas hydrate phases. The different shape of large voids in the semiclathrate hydrates changed to the typical shape of sH or sII large voids, and pentagonal dodecahedra were formed so as to capture CH4 molecules. Transition pattern and molecular behavior from semiclathrate hydrate to true clathrate hydrates were analyzed with PXRD, NMR, and Raman methods. In addition, the liquid mixture−CH4 hydrates−CH4 vapor (L−H−V) thermodynamic equilibrium conditions were measured.

Hexamethyleneimine, 1-methylpiperidine, 2-methylpiperidine, 3-methylpiperidine, and 4-methylpiperidine as isomers of C6H13N were revealed as new sH clathrate hydrate forming molecules. They show fu...