Latest ArticlesSelenium, an element belonging to the same group in the periodic table as sulfur, has a high electronic conductivity (1 × 10−5 S/cm) and a high volumetric energy density (3253 mAh/cm3), which is a prospective cathode material for high-energy all-solid-state rechargeable batteries. However, its wide use is hindered by large volume expansion and low utilization rate. In this work, Se-infused nitrogen-doped hierarchical meso-microporous carbon composites (Se/NHPC) are prepared by a melt-diffusion process. Amorphous Se is uniformly dispersed in meso-micropores of NHPC with a high mass loading of 81%. All-solid-state Li-Se batteries fabricated by using Se/NHPC as the cathode, a Li-In alloy as the anode, and Li6PS5Cl as the solid-state electrolyte, deliver a highly reversible capacity of 621 mAh/g (92% of theoretical capacity), a good rate capability and a high capacity retention value of 80.9% after 100 cycles. It is found that the capacity decay of Se cathode is mainly related to the interfacial degradation and the separation of Se from the carbon substrate, as suggested by the continuous increase of interfacial resistance and the structural transformation from amorphous Sen chains to Se8 rings initial discharge/charge cycle and then to the trigonally crystalline Se chains structure after the long-term cycles.
Functional carbon nanomaterials have become the stars of many active research fields, such as electronics, energy, catalysis, imaging, sensing and biomedicine. Herein, a facile and one-pot strategy for generating ferromagnetic nanoparticles loaded on N-doped carbon nanosheets (Fe-N-CNS) is presented by salt-assisted high-temperature carbonization of natural silk proteins. Due to their graphitic structures, N-doping and ferromagnetic nanoparticles (FeNx, FeOy, FeCz), the silk-derived Fe-N-CNS can act as excellent mimics of both peroxidase and oxidase. Benefiting from the combined character of the graphene-like structures and enzyme-like activities, Fe-N-CNS can be further applied to highly efficient dye removal via synergistic adsorption and degradation. Meanwhile, the as-prepared Fe-N-CNS with intrinsic magnetism and electrical conductivity can also serve as an efficient electromagnetic wave absorption agent. The broadest effective absorption bandwidth (EAB) of as-obtained absorbing material yields a 6.73 GHz with 1 mm thickness, with a maximum reflection loss of −37.33 dB (11.41 GHz). The EAB can cover 2~18 GHz with a tunable absorber thickness from 1.0 mm to 5.0 mm. Collectively, Fe-N-CNS, as a dual-functional material, can tackle the aggravating environmental pollution issues of both dyes and electromagnetic waves.
Metal-support interaction (MSI) is an efficient way in heterogeneous catalysis and electrocatalysis to modulate the electronic structure of metal for enhanced catalytic activity. However, there are still great challenges in promoting the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) simultaneously by this way. Herein, Fe-doped Co3O4 supported Ru (Ru/FeCo) catalysts are synthesized by MSI strategies to further improve the electrocatalytic activity and stability of the catalysts. The results show that the optimized Ru/FeCo catalyst exhibits the best catalytic performance. The HER and OER tests at 10 mA/cm2 in 1 mol/L KOH solution show excellent overpotentials of 155 mV and 283 mV, respectively. The activity and stability enhancement can be attributed to the MSI that effectively modify the electronic structure and improve interfacial electron transfer between Ru and Fe-doped Co3O4 (FeCo). This work provides an innovative direction for the design of high-efficiency bifunctional electrocatalysts by virtue of the MSI.
Organic field-effect transistors (OFETs) refer to field-effect transistors that use organic semiconductors as channel materials. Owing to the advantages of organic materials such as solution processability and intrinsic flexibility, OFETs are expected to be applicable in emergent technologies including wearable electronics and sensors, flexible displays, internet-of-things, neuromorphic computing, etc. Improving the electrical performance and developing multifunctionalities of OFETs are two major and closely relevant aspects for OFETs-related research. The former one aims for investigating the device physics and expanding the horizons of OFETs, while the later one is critical for leading OFETs into practical and emergent applications. The development in each of the two aspects would undoubtfully promote the other and bring more confidence for future development of OFETs. Hence, this review is divided into two parts that respectively summarize the recent progress in high-performance OFETs and multifunctional OFETs.
Organics present significant prospects as environmentally friendly and sustainable electrode materials for potassium ion batteries (PIBs) because of their abundant, recyclable and highly customizable characteristics. However, small molecular organics are easily solubilized in organic electrolytes, resulting in a low capacity and poor stability. Herein, the folic acid-based supermolecules (SM-FAs) are successfully prepared by a hydrothermal assisted self-assembly strategy. Due to multi-locus hydrogen bonds (HBs) and the cyclized π-conjugated interactions, the structural stability of SM-FAs has been significantly improved, and the solubility in carbonate electrolytes has been effectively inhibited. As an anode for PIB, the SM-FA-6 sample exhibits a large capacity (206 mAh/g at 50 mA/g) and an outstanding cycle stability (capacity retention of 91% after 1000 cycles at 50 mA/g). More impressively, an integrative storage mechanism which combines both the general enolization reaction between C=O groups and K+, and the atypical π–K+ interaction within the assembled conjugation framework, is unraveled for potassium ion accumulation. It is envisioned that this facile self-assemble strategy opens up a promising avenue to modulate the stability of small molecular organic electrodes with enhanced storage capacity.
Most porous conductive frameworks are highly anisotropic in their structures thus leading to anisotropic charge transport. Here we report a supramolecular self-assembly which is constructed by intermolecular hydrogen bonding and π···π interactions. This material features a chiral, porous, cubic framework structure with π-stacked helical columns along all of the three Cartesian coordinates. As a result, isotropic charge transport with an electrical conductivity (σ) of 2.1 × 10–7 S/cm is achieved. By achieving isotropic charge transport in a π-stacked supramolecular assembly, these results provide a new type of isotropic conductive framework materials alternative to conductive metal-organic frameworks (MOFs).
Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor, substrate and solvent, which leads to energy loss and obvious heat transfer limits. In this study, induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts. It was found that, at the same apparent reaction temperatures, the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield, as compared to the reactions using conventional joule heating. The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites, which dissipates the electromagnetic energy through Néel relaxation mechanism. Moreover, it has be found that the reactions have been largely accelerated, resulting in much shorter reaction time required to approach a given value of reactant conversion. These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process, and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.
Multifunctional switchable materials are attracting tremendous interest because of their great application potential in signal processing, information encryption, and smart devices. Here, we reported an organic-inorganic hybrid thermochromic ferroelastic crystal, [TMIm][CuCl4] (TMIm = 1,1,3,3-tetramethylimidazolidinium), which undergoes two reversible phase transitions at 333 K and 419 K, respectively. Intriguingly, these three phases experience a remarkable ferroelastic-paraelastic-ferroelastic (2/m-mmm-2/m) transition, which remains relatively unexplored in ferroelastics. Moreover, the ferroelastic domains can be simultaneously switched under temperature and stress stimuli. Meanwhile, [TMIm][CuCl4] exhibits thermochromic phenomenon, endowing it with extra spectral encryption possibilities during information processing. Combined with dielectric switching behavior, [TMIm][CuCl4] are promising for practical applications in memory devices, next-generation sensors, and encryption technology.
Hydrogenation reactions play crucial roles on chemical synthesis and pollutant elimination. The improvement of the ability to activate reactants and increase of the contact probability between the catalysts and reactants are positive to improve the catalytic performance. Herein, we have reported the design of two-dimensional porous Ni-Ni3N-NiMoN heterojunction sheets (2D Mo-Ni based nanosheets) for efficient catalytic hydrogenation of the aromatic nitro-compounds. The heterojunction interfaces provide plentiful active sites to improve the activating ability of the catalyst on the reactants. Additionally, the 2D porous structure facilitates not only the contact of catalytic sites with reactants but also mass transfer and diffusion, both of which are favorable to accelerating the hydrogenation process. As a result, the optimized sample of 2D Mo-Ni sheet exhibits good activity for the hydrogenation of aromatic nitro-compounds by converting 0.2 mmol/L (30 mL) of p-nitrophenol to p-aminophenol within 45 s with good recyclability. The activation energy and the reaction rate at 25 ℃ is 31.11 kJ/mol and 0.0796 s-1, respectively, both of which surpass most of reported non-noble metal catalysts and rivals with most noble metal-based catalysts. The combination of late and early transition metals provides an innovative way to obtain outstanding catalysts for the hydrogenation.