Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g −1 and can sustain 500 cycles at 100 mA g −1 . Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.

The development of a feasible and inexpensive strategy to obtain and utilize sustainable energy is an important issue for the sustainable development of human society. Over the past decade, significant progress has been made in the development of novel functional materials for energy conversion and storage. Owing to their unique physico‐chemical properties, 2D layered materials, such as graphene and transition metal dichalcogenides, have attracted great interest in energy‐related research. 1T‐MoS2 is a metallic phase of molybdenum disulfide (MoS2) with extraordinary electronic conductivity, enlarged interlayer spacing, and more electrochemically active sites along the basal plane, which offers intriguing benefits for energy‐related applications compared to its semiconducting counterpart (2H‐MoS2). This review summarizes the preparation and structure–property relationships of 1T‐MoS2, as well as the underlying relations between the metallic (1T) and semiconducting (2H) phases of MoS2. Recent progress in the preparation and stabilization of 1T‐MoS2 materials and their applications for energy conversion and storage are discussed, including water splitting to form hydrogen via photo/electrocatalysis and electricity storage in lithium‐ion batteries, sodium‐ion batteries, magnesium‐ion batteries, and supercapacitors. Optimization strategies of 1T‐MoS2 to obtain enhanced practical properties based on theoretical calculations are also presented.

The Boltzmann distribution of electrons sets a fundamental barrier to lowering energy consumption in metal-oxide-semiconductor field-effect transistors (MOSFETs). Negative capacitance FET (NC-FET), as an emerging FET architecture, is promising to overcome this thermionic limit and build ultra-low-power consuming electronics. Here, we demonstrate steep-slope NC-FETs based on two-dimensional molybdenum disulfide and CuInP 2 S 6 (CIPS) van der Waals (vdW) heterostructure. The vdW NC-FET provides an average subthreshold swing (SS) less than the Boltzmann’s limit for over seven decades of drain current, with a minimum SS of 28 mV dec −1 . Negligible hysteresis is achieved in NC-FETs with the thickness of CIPS less than 20 nm. A voltage gain of 24 is measured for vdW NC-FET logic inverter. Flexible vdW NC-FET is further demonstrated with sub-60 mV dec −1 switching characteristics under the bending radius down to 3.8 mm. These results demonstrate the great potential of vdW NC-FET for ultra-low-power and flexible applications.

The development of the next‐generation lithium ion battery requires environmental‐friendly electrode materials with long cycle life and high energy density. Organic compounds are a promising potential source of electrode materials for lithium ion batteries due to their advantages of chemical richness at the molecular level, cost benefit, and environmental friendliness, but they suffer from low capacity and dissatisfactory cycle life mainly due to hydrophobic dissolution in organic electrolytes and poor electronic conductivity. In this work, two types of triazine‐based covalent organic nanosheets (CONs) are exfoliated and composited with carbon nanotubes. The thin‐layered 2D structure for the exfoliated CONs can activate more functional groups for lithium storage and boost the utilization efficiency of redox sites compared to its bulk counterpart. Large reversible capacities of above 1000 mAh g−1 can be achieved after 250 cycles, which is comparable to high‐capacity inorganic electrodes. Moreover, the lithium‐storage mechanism is determined to be an intriguing 11 and 16 electron redox reaction, associated with the organic groups (unusual triazine ring, piperazine ring, and benzene ring, and common CN, NH groups).

Outcome evaluation is a cognitive process that plays an important role in our daily lives. In most paradigms utilized in the field of experimental psychology, outcome valence and outcome magnitude are the two major features investigated. The classical “independent coding model” suggest that outcome valence and outcome magnitude are evaluated by separate neural mechanisms that may be mapped onto discrete event-related potential (ERP) components: feedback-related negativity (FRN) and the P3, respectively. To examine this model, we presented outcome valence and magnitude sequentially rather than simultaneously. The results reveal that when only outcome valence or magnitude is known, both the FRN and the P3 encode that outcome feature; when both aspects of outcome are known, the cognitive functions of the two components dissociate: the FRN responds to the information available in the current context, while the P3 pattern depends on outcome presentation sequence. The current study indicates that the human evaluative system, indexed in part by the FRN and the P3, is more flexible than previous theories suggested.

Upconversion nanoparticles (UCNPs) doped with lanthanide ions that possess ladder‐like energy levels can give out multiple emissions at specific ultra‐violet or visible wavelengths irrespective of excitation light. However, precisely controlling energy migration processes between different energy levels of the same lanthanide ion to generate switchable emissions remains elusive. Herein, a novel dumbbell‐shaped UCNP is reported with upconverted red emission switched to green emission when excitation wavelength changed from 980 to 808 nm. The sensitizer Yb ions are doped with activator Er ions and energy modulator Mn ions in NaYF4 core nanocrystal coated with an inner NaYF4:Yb shell to generate red emission after harvesting 980 nm excitation light, while an outer NaNdF4:Yb shell is coated to form a dumbbell shape to generate green emission upon 808 nm excitation. Such specially designed UCNPs with switchable green and red emissions are further explored for imaging of latent fingerprint and detection of explosive residues in the fingerprint simultaneously. This work suggests a novel research interest in fine‐tuning of upconversion emissions through precisely controlling energy migration processes of the same lanthanide activator ion. Furthermore, use of these nanoparticles in other applications such as simultaneous dual‐color imaging or orthogonal bidirectional photoactivation can be explored.

www.advancedsciencenews.comreaction is more unfavorable. [22,23] Comparing to the researches on artificial H 2 production, the knowledge referring to efficient and selective reduction of CO 2 to energy-rich molecules is urgent to be updated. CO 2 conversion is often traced back to 1972 that reported by Honda and Fujishima with using inorganic photocatalysts TiO 2 . [24] As the capture of CO 2 has already been studied in metal-organic frameworks (MOFs), [25][26][27][28] it has recently been studied for their use as catalysts for the reduction of CO 2 into high-value chemicals. [14,29] MOFs hold great promise for applications in the field of CO 2 reduction, which can act directly as the catalysts or as components to promote CO 2 reduction in a hybrid catalytic system. The interior of MOFs can be designed to have open metal sites, specific heteroatoms, functionalized organic ligand, other building unit interactions, hydrophobicity, defects, porosity, and embedded nanoscale metal catalysts which is crucial for the development of better CO 2 reduction performance MOFs. [30][31][32] Due to the poor electron conductivity of MOFs, [33,34] and the inaccessibility of all the catalytic active sites to the reactants, the stability of MOFs in water and under UV light irradiation need to be further improved. We believe that a comprehensive and up-to-date review summarizing the recent applications of MOFs for CO 2 reduction will contribute to improve theoretical understanding of this field. In order to make a better achievement, it is necessary to use the MOF to build more complex materials to address CO 2 capacity and reduction ability together in one material. Future MOFs materials for CO 2 reduction should be economical and environmental friendly. The keys for promoting catalysis include structural defects in the MOFs, open metal sites from metal clusters, Lewis acid sites from the metal cluster and organometallic linker, and cocatalyst functionalized MOFs.Several reviews focusing on MOFs for CO 2 conversion have been recently reviewed and discussed. Dhakshinamoorthy et al. pointed out that photoexcitation of the light absorbing units in MOFs often generates a ligand-to-metal charge-separation state that can result in photocatalytic activity. Maina et al. discussed the corelationship between the properties of MOF materials including their CO 2 reduction catalytic performance under different reaction conditions. Li and co-workers have summarized the recent applications of MOFs for photocatalytic CO 2 reduction, in which MOFs can act as the photocatalysts for CO 2 reduction or as components in a hybrid photocatalytic system to promote CO 2 reduction. Yaghi and co-workers also pointed out that the challenge in developing catalysts for CO 2 photo-or electroreduction is rooted in the interplay between selectivity, activity, and efficiency. [35][36][37][38] Synthetic Approaches for MOFsMOFs, also called porous coordination polymers, are extended framework with open structures constructed from metal ions and organic ligands linked...

Downsizing the cell size of honeycomb monoliths to nanoscale would offer high freedom of nanostructure design beyond their capability for broad applications in different fields. However, the microminiaturization of honeycomb monoliths remains a challenge. Here, we report the fabrication of microminiaturized honeycomb monoliths-honeycomb alumina nanoscaffold-and thus as a robust nanostructuring platform to assemble active materials for microsupercapacitors. The representative honeycomb alumina nanoscaffold with hexagonal cell arrangement and 400 nm inter-cell spacing has an ultrathin but stiff nanoscaffold with only 16 ± 2 nm cell-wall-thickness, resulting in a cell density of 4.65 × 10 9 cells per square inch, a surface area enhancement factor of 240, and a relative density of 0.0784. These features allow nanoelectrodes based on honeycomb alumina nanoscaffold synergizing both effective ion migration and ample electroactive surface area within limited footprint. A microsupercapacitor is finally constructed and exhibits record high performance, suggesting the feasibility of the current design for energy storage devices.