201709纳米材料、电池领域—经典综述文章

Abstract：

Great endeavors are undertaken to search for low-cost, rich-reserve, and highly efficient alternatives to replace precious-metal catalysts, in order to cut costs and improve the efficiency of catalysts in industry. However, one major problem in metal catalysts, especially nonprecious-metal catalysts, is their poor stability in real catalytic processes. Recently, a novel and promising strategy to construct 2D materials encapsulating nonprecious-metal catalysts has exhibited inimitable advantages toward catalysis, especially under harsh conditions (e.g., strong acidity or alkalinity, high temperature, and high overpotential). The concept, which originates from unique electron penetration

through the 2D crystal layer from the encapsulated metals to promote a catalytic reaction on the outermost surface of the 2D crystal, has been widely applied in a variety of reactions under harsh conditions. It has been vividly described as “chainmail for catalyst.” Herein, recent progress concerning this chainmail catalyst is reviewed, particularly focusing on the structural design and control with the associated electronic properties of such heterostructure catalysts, and also on their extensive applications in fuel cells, water splitting, CO2 conversion, solar cells, metal–air batteries, and heterogeneous catalysis. In addition, the current challenges that are faced in fundamental research and industrial application, and future opportunities for these fantastic catalytic materials are discussed.

Abstract：

Hybrid metal-ion capacitors (MICs) (M stands for Li or Na) are designed to deliver high energy density, rapid energy delivery, and long lifespan. The devices are composed of a battery anode and a supercapacitor cathode, and thus become a tradeoff between batteries and supercapacitors. In the past two decades, tremendous efforts have been put into the search for suitable electrode materials to overcome the kinetic imbalance between the batterytype anode and the capacitor-type cathode. Recently, some transition-metal compounds have been found to show pseudocapacitive characteristics in a nonaqueous electrolyte, which makes them interesting high-rate candidates for hybrid MIC anodes. Here, the material design strategies in Li-ion and Na-ion capacitors are summarized, with a focus on pseudocapacitive oxide anodes (Nb2O5, MoO3, etc.), which provide a new opportunity to obtain a higher power density of the hybrid devices. The application of Mxene as an anode material of MICs is also discussed. A perspective to the future research of MICs toward practical applications is proposed to close.

Abstract：

The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of largescale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium–oxygen (Na–O2) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na–O2 battery is lower than that of the lithium–oxygen (Li–O2) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry,

to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium–oxygen and sodium–oxygen cells. An in-depth understanding of the differences and similarities between Li–O2 and Na–O2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal–oxygen batteries. State-of-the-art battery design principles for highenergy-density lithium–oxygen and sodium–oxygen batteries are thus

reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized.

Abstract：

The rapid increase of the CO2 concentration in the Earth’s atmosphere has resulted in numerous environmental issues, such as global warming, ocean acidification, melting of the polar ice, rising sea level, and extinction of species. To search for suitable and capable catalytic systems for CO2 conversion, electrochemical reduction of CO2 (CO2RR) holds great promise. Emerging heterogeneous carbon materials have been considered as promising metal-free electrocatalysts for the CO2RR, owing to their abundant natural resources, tailorable porous structures, resistance to acids and bases,

high-temperature stability, and environmental friendliness. They exhibit remarkable CO2RR properties, including catalytic activity, long durability, and high selectivity. Here, various carbon materials (e.g., carbon fibers, carbon nanotubes, graphene, diamond, nanoporous carbon, and graphene dots) with heteroatom doping (e.g., N, S, and B) that can be used as metal-free catalysts for the CO2RR are highlighted. Recent advances regarding the identification of active sites for the CO2RR and the pathway of reduction of CO2 to the final product are comprehensively reviewed. Additionally, the emerging challenges and some perspectives on the development of heteroatom-doped carbon

materials as metal-free electrocatalysts for the CO2RR are included.

Abstract：

Neural interfaces are becoming a powerful toolkit for clinical interventions requiring stimulation and/or recording of the electrical activity of the nervous system. Active implantable devices offer a promising approach for the treatment of various diseases affecting the central or peripheral nervous systems by electrically stimulating different neuronal structures. All currently used neural interface devices are designed to perform a single function: either record activity or electrically stimulate tissue. Because of their electrical and electrochemical performance and their suitability for integration into flexible

devices, graphene-based materials constitute a versatile platform that could help address many of the current challenges in neural interface design. Here, how graphene and other 2D materials possess an array of properties that can enable enhanced functional capabilities for neural interfaces is illustrated. It is emphasized that the technological challenges are similar for all alternative types of materials used in the engineering of neural interface devices, each offering a unique set of advantages and limitations. Graphene and 2D materials can indeed play a commanding role in the efforts toward wider clinical adoption of bioelectronics and electroceuticals.

Abstract：

The efficient handling of wastewater pollutants is a must, since they are continuously defiling limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. Our vision is to undertake an exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption,

catalysis, separation, and disinfection. Additionally, NM-based sensor technologies are considered, since they have been significantly used for monitoring water contaminants. We also suggest future directions to inform investigators of potentially disruptive NM technologies that have to be investigated in more detail.The fate and environmental transformations of NMs, which need to be addressed before large-scale implementation of NMs for water purification, are also highlighted.

Abstract：

Metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs) are two emerging and explosively growing families of crystalline porous materials (CPMs). These robust frameworks are characterized by their extraordinary porosity, tremendous structural diversity, and versatile functional tunability with precision at the molecular level. In this review, we present recent milestones of MOFs and COFs in the fields of batteries and supercapacitors, two important technologies in electrochemical energy storage (EES), and highlight the functions that a CPM can offer in EES devices, including the storage of electrochemical energy, stabilization of electrode materials, pathways for charge transport, manipulation on mass transport, and promotion of electrochemical reactions. Key requirements for each function are discussed, with future directions provided for further development.

Abstract：

The demand for flexible power sources with high energy density and durability increases rapidly with the development of flexible and wearable electronic devices. Metal-air batteries are considered as the most promising candidates for these applications due to their excellent theoretical energy densities. In particular, rechargeable zinc-air and lithium-air batteries have attracted much attention because of their potential to offer a high energy density while maintaining a long operational life. Although significant progress has been made in enhancing the electrochemical performance of these batteries, many technical challenges still remain to achieve the mechanical flexibility required for wearable electronic devices while maintaining high performance. This article describes the most recent advances and challenges in the development of flexible zinc-air and lithium-air batteries. We start with an overview of the latest innovations in the exploration of various battery configurations to effectively accommodate stresses and strains associated with the use of flexible electronic devices. This is followed by a detailed review of the advancements made in designs of flexible battery components: the metal electrode, the electrolyte membrane, and the air electrode. Further, the effects of operating conditions on battery performance characteristics and durabilities are discussed, including the effect of the operating temperature and the contaminants commonly encountered in ambient air (e.g., carbon dioxide and moisture). Finally, challenges facing the development of a new generation of flexible metal-air batteries are highlighted, together with further research directions and perspectives.

Abstract：

Recent interest in flexible electronics has led to a paradigm shift in consumer

electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics.Organic electronic materials, such as π-conjugated small molecules and polymers,are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon.However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions,and chemical stability related to fabrication processes. Recently, however,many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted.