Nano Materials Science最新文献

Aerosol deposition (AD) method is a kind of additive manufacturing technology for fabricating dense films such as metals and ceramics at room temperature. It resolves the challenge of integrating ceramic films onto temperature-sensitive substrates, including metals, glasses, and polymers. It should be emphasized that the AD is a spray coating technology that uses powder without thermal assistance to generate films with high density. Compared to the traditional sputter-based approach, the AD shows several advantages in efficiency, convenience, better interfacial bonding and so on. Therefore, it opens some possibilities to the field of batteries, especially all-solid-state batteries (ASSBs) and draws much attention not only for research but also for large scale applications.

The purpose of this work is to provide a critical review on the science and technology of AD as well as its applications in the field of batteries. The process, mechanism and effective parameters of AD, and recent developments in AD applications in the field of batteries will be systematically reviewed so that a trend for AD will be finally provided.

Despite the engineering potential by the co-existence of inorganic and organic substances to protect vulnerable metallic materials from corrosive environments, both their interaction and in-situ formation mechanism to induce the nature-inspired composite remained less understood. The present work used three distinctive mercapto-benzazole (MB) compounds working as corrosion inhibitors, such as 2-mercaptobenzoxazole (MBO), 2-mercaptobenzothiazole (MBT), and 2-mercaptobenzimidazole (MBI) in a bid to understand how the geometrical structure arising from O, S, and N atoms affected the interaction toward inorganic layer. MB compounds that were used here to control the corrosion kinetics would be interacted readily with the pre-existing MgO layer fabricated by plasma electrolysis. This phenomenon triggered the nucleation of the root network since MB compounds were seen to be adsorbed actively on the defective surface through the active sites in MB compound. Then, the molecule with twin donor atoms adjacent to the mercapto-sites affected the facile growth of the grass-like structures with ‘uniform’ distribution via molecular self-assembly, which showed better corrosion performance than those with having dissimilar donor atoms with the inhibition efficiency (η) of 97% approximately. The formation mechanism underlying nucleation and growth behavior of MB molecule was discussed concerning the theoretical calculation of density functional theory.

With an extensive range of distinctive features at nano meter-scale thicknesses, two-dimensional (2D) materials drawn the attention of the scientific community. Despite tremendous advancements in exploratory research on 2D materials, knowledge of 2D electrical transport and carrier dynamics still in its infancy. Thus, here we highlighted the electrical characteristics of 2D materials with electronic band structure, electronic transport, dielectric constant, carriers mobility. The atomic thinness of 2D materials makes substantially scaled field-effect transistors (FETs) with reduced short-channel effects conceivable, even though strong carrier mobility required for high performance, low-voltage device operations. We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications. Presently, Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure. 2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors. We also, describe the numerous 2D p-n junctions, such as homo junction and hetero junction including mixed dimensional junctions. Finally, we talked about the problems and potential for the future.

Multifunctional and flexible wearable devices play a crucial role in a wide range of applications, such as heath monitoring, intelligent skins, and human-machine interactions. Developing flexible and conductive materials for multifunctional wearable devices with low-cost and high efficiency methods are highly desirable. Here, a conductive graphene/microsphere/bamboo fiber (GMB) nanocomposite paper with hierarchical surface microstructures is successfully fabricated through a simple vacuum-assisted filtration followed by thermo-foaming process. The as-prepared microstructured GMB nanocomposite paper exhibits not only a high volume electrical conductivity of ∼45 ​S/m but also an excellent electrical stability (i.e., relative changes in resistance are less than 3% under stretching, folding, and compressing loadings) due to its unique structure features. With this microstructured nanocomposite paper as active sensing layer, microstructured pressure sensors with a high sensitivity (−4 ​kPa⁻¹), a wide sensing range (0–5 ​kPa), and a rapid response time (about 140 ​ms) are realized. In addition, benefitting from the outstanding electrical stability and mechanical flexibility, the microstructured nanocomposite paper is further demonstrated as a low-voltage Joule heating device. The surface temperature of the microstructured nanocomposite paper rapidly reaches over 80 ​°C when applying a relatively low voltage of 7 ​V, indicating its potential in human thermotherapy and thermal management.

Since the discovery of mesoporous silica in 1990s, there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications, aiming at enhanced catalytic activity and stability. Recently, there have also been considerable interests in endowing them with hierarchical porosities to overcome the diffusional limitation for those with long unimodal channels. Present processes of making mesoporous silica largely rely on chemical sources which are relatively expensive and impose environmental concerns on their processes. In this regard, it is desirable to develop hierarchical silica supports from natural minerals. Herein, we present a series of work on surface reconstruction, modification, and functionalization to produce diatomite-based catalysts with original morphology and macro-meso-micro porosities and to test their suitability as catalyst supports for both liquid- and gas-phase reactions. Two wet-chemical routes were developed to introduce mesoporosity to both amorphous and crystalline diatomites. Importantly, we have used computational modeling to affirm that the diatomite morphology can improve catalytic performance based on fluid dynamics simulations. Thus, one could obtain this type of catalysts from numerous natural diatoms that have inherently intricate morphologies and shapes in micrometer scale. In principle, such catalytic nanocomposites acting as miniaturized industrial catalysts could be employed in microfluidic reactors for process intensification.

Electrically conductive elastomer composites (CECs) with segregated networks of conductive nanofillers show high potential in stretchable strain sensors due to balanced mechanical and electrical properties, yet the sensitivity at low strain is generally insufficient for practical application. Herein, we report an easy and effective way to improve the resistive response to low strain for CECs with segregated network structure via adding stiff alumina into carbon nanostructures (CNS). The CEC containing 0.7 ​wt% CNS and 5 ​wt% Al₂O₃ almost sustains the same elasticity (elongation at break of ∼900%) and conductivity (0.8 ​S/m) as the control, while the piezoresistive sensitivity is significantly improved. Thermoplastic polyurethane (TPU) composites with a segregated network of hybrid nanofillers (CNS and Al₂O₃) show much higher strain sensitivity (Gauge factor, GF ​= ​566) at low strain (45% strain) due to a local stress concentration effect, this sensitivity is superior to that of TPU/CNS composites (GF ​= ​11). Such a local stress concentration effect depends on alumina content and its distribution at the TPU particle interface. In addition, CECs with hybrid fillers show better reproducibility in cyclic piezoresistive behavior testing than the control. This work offers an easy method for fabricating CECs with a segregated filler network offering stretchable strain sensors with a high strain sensitivity.

The oxygen reduction reaction (ORR) electrocatalytic activity of Pt-based catalysts can be significantly improved by supporting Pt and its alloy nanoparticles (NPs) on a porous carbon support with large surface area. However, such catalysts are often obtained by constructing porous carbon support followed by depositing Pt and its alloy NPs inside the pores, in which the migration and agglomeration of Pt NPs are inevitable under harsh operating conditions owing to the relatively weak interaction between NPs and carbon support. Here we develop a facile electrospinning strategy to in-situ prepare small-sized PtZn NPs supported on porous nitrogen-doped carbon nanofibers. Electrochemical results demonstrate that the as-prepared PtZn alloy catalyst exhibits excellent initial ORR activity with a half-wave potential (E_1/2) of 0.911 ​V versus reversible hydrogen electrode (vs. RHE) and enhanced durability with only decreasing 11 ​mV after 30,000 potential cycles, compared to a more significant drop of 24 ​mV in E_1/2 of Pt/C catalysts (after 10,000 potential cycling). Such a desirable performance is ascribed to the created triple-phase reaction boundary assisted by the evaporation of Zn and strengthened interaction between nanoparticles and the carbon support, inhibiting the migration and aggregation of NPs during the ORR.

Electronic skin and flexible wearable devices have attracted tremendous attention in the fields of human-machine interaction, energy storage, and intelligent robots. As a prevailing flexible pressure sensor with high performance, the piezoresistive sensor is believed to be one of the fundamental components of intelligent tactile skin. Furthermore, graphene can be used as a building block for highly flexible and wearable piezoresistive sensors owing to its light weight, high electrical conductivity, and excellent mechanical. This review provides a comprehensive summary of recent advances in graphene-based piezoresistive sensors, which we systematically classify as various configurations including one-dimensional fiber, two-dimensional thin film, and three-dimensional foam geometries, followed by examples of practical applications for health monitoring, human motion sensing, multifunctional sensing, and system integration. We also present the sensing mechanisms and evaluation parameters of piezoresistive sensors. This review delivers broad insights on existing graphene-based piezoresistive sensors and challenges for the future generation of high-performance, multifunctional sensors in various applications.

The future intelligent era that will be brought about by 5G technology can be well predicted. For example, the connection between humans and smart wearable devices will become increasingly more intimate. Flexible wearable pressure sensors have received much attention as a part of this process. Nevertheless, there is a lack of complete and detailed discussion on the recent research status of capacitive pressure sensors composed of polymer composites. Therefore, this article will mainly discuss the key concepts, preparation methods and main performance of flexible wearable capacitive sensors. The concept of a processing “toolbox” is used to review the developmental status of the dielectric layer as revealed in highly cited literature from the past five years. The preparation methods are categorized into types of processing: primary and secondary. Using these categories, the preparation methods and structure of the dielectric layer are discussed. Their influence on the final capacitive sensing behavior is also addressed. Recent developments in the electrode layer are also systematically reviewed. Finally, the results of the above discussion are summarized and future development trends are discussed.