Giant nanomechanical energy storage capacity in twisted single-walled carbon nanotube ropes.

A sustainable society requires high-energy storage devices characterized by lightness, compactness, a long life and superior safety, surpassing current battery and supercapacitor technologies. Single-walled carbon nanotubes (SWCNTs), which typically exhibit great toughness, have emerged as promising candidates for innovative energy storage solutions. Here we produced SWCNT ropes wrapped in thermoplastic polyurethane elastomers, and demonstrated experimentally that a twisted rope composed of these SWCNTs possesses the remarkable ability to reversibly store nanomechanical energy. Notably, the gravimetric energy density of these twisted ropes reaches up to 2.1 MJ kg-1, exceeding the energy storage capacity of mechanical steel springs by over four orders of magnitude and surpassing advanced lithium-ion batteries by a factor of three. In contrast to chemical and electrochemical energy carriers, the nanomechanical energy stored in a twisted SWCNT rope is safe even in hostile environments. This energy does not deplete over time and is accessible at temperatures ranging from -60 to +100 °C.

Photoreaction products of extract from the fruiting bodies of Polyozellus multiplex.

Photochemical reactions are powerful tools for synthesizing organic molecules. The input of energy provided by light offers a means to produce strained and unique molecules that cannot be assembled using thermal protocols, allowing for the production of immense molecular complexity in a single chemical step. Furthermore, unlike thermal reactions, photochemical reactions do not require active reagents such as acids, bases, metals, or enzymes. Photochemical reactions play a central role in green chemistry. This article reports the isolation and structure determination of four new compounds (1-4) from the photoreaction products of the Polyozellus multiplex MeOH ext. The structures of the new compounds were elucidated using MS, IR, comprehensive NMR measurements and microED. The four compounds were formed by deacetylation of polyozellin, the main secondary metabolite of P. multiplex, and addition of singlet oxygen generated by sunlight. To develop drugs for treating Alzheimer's disease (AD) on the basis of the amyloid cascade hypothesis, the compounds (1-4) obtained by photoreaction were evaluated for BACE1 inhibitory activity. The hydrolysates (5 and 6) of polyozellin, the main secondary metabolites of P. multiplex, were also evaluated. The photoreaction products (3 and 4) and hydrolysates (5 and 6) of polyozellin showed BACE1 inhibitory activity (IC50: 2.2, 16.4, 23.3, and 5.3 µM, respectively).

Transient chemical and structural changes in graphene oxide during ripening.

Graphene oxide (GO)-the oxidized form of graphene-is actively studied in various fields, such as energy, electronic devices, separation of water, materials engineering, and medical technologies, owing to its fascinating physicochemical properties. One major drawback of GO is its instability, which leads to the difficulties in product management. A physicochemical understanding of the ever-changing nature of GO can remove the barrier for its growing applications. Here, we evidencde the presence of intrinsic, metastable and transient GO states upon ripening. The three GO states are identified using a [Formula: see text] transition peak of ultraviolet-visible absorption spectra and exhibit inherent magnetic and electrical properties. The presence of three states of GO is supported by the compositional changes of oxygen functional groups detected via X-ray photoelectron spectroscopy and structural information from X-ray diffraction analysis and transmission electron microscopy. Although intrinsic GO having a [Formula: see text] transition at 230.5 ± 0.5 nm is stable only for 5 days at 298 K, the intrinsic state can be stabilized by either storing GO dispersions below 255 K or by adding ammonium peroxydisulfate.

Designed Production of Atomic-Scale Nanowindows in Single-Walled Carbon Nanotubes.

The controlled production of nanowindows in graphene layers is desirable for the development of ultrathin membranes. Herein, we propose a single-atom catalytic oxidation method for introducing nanowindows into the graphene layers of single-walled carbon nanotubes (SWCNTs). Using liquid-phase adsorption, copper(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (CuPc) was adsorbed on SWCNT bundles at a surface coverage of 0.9. Subsequently, narrow nanowindows with a number density of 0.13 nm-2 were produced by oxidation above 550 K, which is higher than the decomposition temperature of bulk CuPc. In particular, oxidation of the CuPc-adsorbed SWCNTs at 623 K increased the surface area from 280 to 1690 m2 g-1 owing to the efficient production of nanowindows. The nanowindow size was estimated to be similar to the molecular size of N2 based on the pronounced low-pressure adsorption hysteresis in the N2 adsorption isotherm. In addition, the enthalpy change for the nanowindow-formation equilibrium decreased by 4 kJ mol-1 when CuPc was present, further evidencing the catalytic effect of the Cu atoms supplied by the adsorbed CuPc molecules.

Ultrapermeable 2D-channeled graphene-wrapped zeolite molecular sieving membranes for hydrogen separation.

The efficient separation of hydrogen from methane and light hydrocarbons for clean energy applications remains a technical challenge in membrane science. To address this issue, we prepared a graphene-wrapped MFI (G-MFI) molecular-sieving membrane for the ultrafast separation of hydrogen from methane at a permeability reaching 5.8 × 106 barrers at a single gas selectivity of 245 and a mixed gas selectivity of 50. Our results set an upper bound for hydrogen separation. Efficient molecular sieving comes from the subnanoscale interfacial space between graphene and zeolite crystal faces according to molecular dynamic simulations. The hierarchical pore structure of the G-MFI membrane enabled rapid permeability, indicating a promising route for the ultrafast separation of hydrogen/methane and carbon dioxide/methane in view of energy-efficient industrial gas separation.

Magnetic-Field-Induced Liquid Phase Transformation of an Ionic Liquid N,N,N-Trimethyl-N-propylammonium Bis(trifluoromethanesulfonyl)imide.

An ionic liquid, N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide (TMPA TFSI), was transformed from a liquid phase to another fluidic phase by application of the threshold magnetic field at constant temperature (T). The magnetic-field-induced (MFI) phase transformation was detected by the electric potential generated between two Pt electrodes set to the bottom and upper parts in a TMPA TFSI liquid during sweep of the magnetic field (B). The magnetic susceptibility and Verdet constant of TMPA TFSI also were slightly changed over 3 T. The MFI phase formation was almost completed within 3 h after TMPA TFSI liquid was exposed to a 6 T magnetic field, as demonstrated by the melting behavior of TMPA TFSI solid frozen instantaneously under 6 T. Multivariate analysis of the Raman spectra suggested that the MFI transformation should be associated with the conformational change of the transoid-to-cisoidlike species of TFSI ions. A B-T phase diagram of TMPA TFSI is proposed.