Ordered porous films of single-walled carbon nanotubes using an ionic exchange reaction

Enhanced Interface Charge Carrier Transport of SnO2/CeO2 via Oxygen Vacancy Synergized Heterojunction for Triethylamine Sensing Property

Efficient charge carrier transport characteristics are critical to achieving the excellent performance of metal-oxide semiconductor gas sensors. Herein, SnO2/CeO2 heterojunction layered nanosheets with abundant oxygen vacancies were successfully synthesized through a simple solvothermal assisted high-temperature calcination method. The synergistic effect of oxygen vacancies and heterojunctions promoting the charge carrier transport properties at the SnO2/CeO2 interface for the enhanced sensing properties of triethylamine (TEA) was highlighted. As a result, the optimized SnO2/CeO2 exhibits improved gas sensing performance at 173 °C to 50 ppm of TEA. These include high response (205), excellent selectivity, low detection limit, and good long-term stability. This enhanced gas sensing property of SnO2/CeO2 is mainly attributed to the fact that the heterojunction and oxygen vacancies act as dual active sites synergistically inducing electron transfer, thereby effectively modulating the transport properties of the interfacial charge carriers, and thus facilitate the surface reactions efficiently. In this work, the dual-engineering strategy of synergistic interaction of heterojunction and oxygen vacancies can provide new perspectives for the design of advanced gas sensing materials.

Electrolytic Graphene Encapsulated CeO2 for Lithium-Sulfur Battery Interlayer Separator

Rare earth elements and graphene composites exhibit better catalytic properties in energy storage materials. The introduction of rare earth oxide and graphene composites as functional layers into the separator to seal the "shuttle effect" formed by polysulfides during the discharge process has proven to be effective. In this study, we prepared CeO2/graphene composites (labeled as CeG) by intercalation exfoliation and in situ electrodeposition methods simultaneously, in which CeO2 was encapsulated in large folds of graphene, which exhibited good defect levels (ID/IG < 1) and its intrinsically superior physical structure acted as a shielding layer to hinder the shuttle of polysulfides, improving the cycling stability and rate of cell performance. The separator cell with CeG achieves an initial discharge specific capacity of 1133.5 mAh/g at 0.5C, excellent rate performance (978.5 mAh/g at 2C), and long cycling (790 mAh/g after 400 cycles).

Strain Tunable Thermoelectric Material: Janus ZrSSe Monolayer

Thermoelectric (TE) performance of the Janus ZrSSe monolayer under biaxial strain is systematically explored by the first-principles approach and Boltzmann transport theory. Our results show that the Janus ZrSSe monolayer has excellent chemical, dynamical, thermal, and mechanical stabilities, which provide a reliable platform for strain tuning. The electronic structure and TE transport parameters of the Janus ZrSSe monolayer can be obviously tuned by biaxial strain. Under 2% tensile strain, the optimal power factor PF of the n-type-doped Janus ZrSSe monolayer reaches 46.36 m W m^-1 K^-2 at 300 K. This value is higher than that of the most classical TE materials. Under 6% tensile strain, the maximum ZT values for the p-type- and n-type-doped Janus ZrSSe monolayers are 4.41 and 4.88, respectively, which are about 3.83 and 1.49 times the results of no strain, respectively. Such high TE performance can be attributed to high band degeneracy and short phonon relaxation time under strain, causing simultaneous increase of the Seebeck coefficient and suppression of the phonon thermal transport. Present work demonstrates that the Janus ZrSSe monolayer is a promising candidate as a strain-tunable TE material and stimulates further experimental synthesis.

In Silico Study of the Influence of Various Substrates on the Electronic Properties and Electrical Conductivity of Mono- and Bilayer Films of Armchair Single-Walled Carbon Nanotubes

We investigate electronic and electro-physical properties of mono- and bilayer armchair single-walled carbon nanotube (SWCNT) films located on substrates of different types, including substrates in the form of crystalline silicon dioxide (SiO2) films with P42/mnm and P3121 space symmetry groups. The SWCNT films interact with substrate only by van der Waals forces. The densities of electronic states (DOS) and the electron transmission functions are calculated for SWCNT films with various substrates. The electrical conductivity of SWCNT films is calculated based on the electron transmission function. It is found that the substrate plays an important role in the formation of DOS of the SWCNT films, and the surface topology determines the degree and nature of the mutual influence of the nanotube and the substrate. It is shown that the substrate affects the electronic properties of monolayer films, changing the electrical resistance value from 2% to 17%. However, the substrate has practically no effect on the electrical conductivity and resistance of the bilayer film in both directions of current transfer. In this case, the values of the resistances of the bilayer film in both directions of current transfer approach the value of ~6.4 kΩ, which is the lowest for individual SWCNT.

Enzyme-Regulated Healable Polymeric Hydrogels

The enzyme-regulated healable polymeric hydrogels are a kind of emerging soft material capable of repairing the structural defects and recovering the hydrogel properties, wherein their fabrication, self-healing, or degradation is mediated by enzymatic reactions. Despite achievements that have been made in controllable cross-linking and de-cross-linking of hydrogels by utilizing enzyme-catalyzed reactions in the past few years, this substrate-specific strategy for regulating healable polymeric hydrogels remains in its infancy, because both the intelligence and practicality of current man-made enzyme-regulated healable materials are far below the levels of living organisms. A systematic summary of current achievements and a reasonable prospect at this point can play positive roles for the future development in this field. This Outlook focuses on the emerging and rapidly developing research area of bioinspired enzyme-regulated self-healing polymeric hydrogel systems. The enzymatic fabrication and degradation of healable polymeric hydrogels, as well as the enzymatically regulated self-healing of polymeric hydrogels, are reviewed. The functions and applications of the enzyme-regulated healable polymeric hydrogels are discussed.

Nanoscale Patterning of Carbon Nanotubes: Techniques, Applications, and Future

Carbon nanotube (CNT) devices and electronics are achieving maturity and directly competing or surpassing devices that use conventional materials. CNTs have demonstrated ballistic conduction, minimal scaling effects, high current capacity, low power requirements, and excellent optical/photonic properties; making them the ideal candidate for a new material to replace conventional materials in next-generation electronic and photonic systems. CNTs also demonstrate high stability and flexibility, allowing them to be used in flexible, printable, and/or biocompatible electronics. However, a major challenge to fully commercialize these devices is the scalable placement of CNTs into desired micro/nanopatterns and architectures to translate the superior properties of CNTs into macroscale devices. Precise and high throughput patterning becomes increasingly difficult at nanoscale resolution, but it is essential to fully realize the benefits of CNTs. The relatively long, high aspect ratio structures of CNTs must be preserved to maintain their functionalities, consequently making them more difficult to pattern than conventional materials like metals and polymers. This review comprehensively explores the recent development of innovative CNT patterning techniques with nanoscale lateral resolution. Each technique is critically analyzed and applications for the nanoscale-resolution approaches are demonstrated. Promising techniques and the challenges ahead for future devices and applications are discussed.