Small structures 

About: Small structures is an academic journal published by Wiley. The journal publishes majorly in the area(s): Chemistry & Engineering. It has an ISSN identifier of 2688-4062. Over the lifetime, 259 publications have been published receiving 1300 citations.

2D MXene Nanomaterials: Synthesis, Mechanism, and Multifunctional Applications in Microwave Absorption

Abstract: MXene nanomaterials stand out among 2D nanomaterials and have been extensively studied by researchers because of their unique layered structure, chemical diversity, and outstanding chemical and physical properties. In recent years, MXene materials have rapidly opened the market for electromagnetic interference shielding technology due to their excellent electromagnetic wave absorption (EMA) capability. However, so far, compared with the development of electromagnetic (EM) shielding technology, there is still much room for development in the construction of MXenes and the application of electromagnetic wave absorption. Herein, the construction strategies, electromagnetic wave conversion mechanism, and applications of MXenes materials are reviewed. Through meticulous material design and an interdisciplinary approach, 2D MXene materials are expected to become one of the smart tunable wave absorbers, and their application scenarios will also become broader.

Current Progress in 2D Metal–Organic Frameworks for Electrocatalysis

Abstract: The 2D nanosheets of metal–organic frameworks (MOFs) have recently emerged as a promising material that makes them valuable in widespread electrocatalytic fields due to their atomic‐level thickness, abundant active sites, and large surface area. Efficient electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting are highly desired with low overpotentials to promote the industrial applications of energy conversion and devices. 2D MOF nanostructures provide long‐term stability and high electrical conductivity to enhance catalyst activity and durability. This review briefly summarizes the synthesis and electrocatalytic applications of 2D MOF for HER/OER/water splitting. More attention is focused on the synthetic strategies of 2D MOF and their derivatives. The catalytic performance and superior properties of these materials are highlighted. The outperformance of these materials originates from the rational design, myriad of abundant active sites, and atomic‐level thickness. The current and future challenges in this field and the scientific perspectives to overcome these challenges are highlighted. It is suggested that the construction of 2D MOF nanostructures can develop a state‐of‐the‐art electrocatalyst in energy and environmental division.

Mainstream Optimization Strategies for Cathode Materials of Sodium‐Ion Batteries

Abstract: Sodium‐ion batteries are promising candidates for grid‐scale energy storage due to its abundance and similarities to lithium‐ion batteries, whereas the lack of ideal cathode materials limits their practical development. Apart from exploring novel materials, applying optimization strategies on existing potential cathode materials is demonstrated to be effective and efficient in improving their electrochemical properties toward their theoretical best capabilities. Reported strategies include element doping, surface coating, morphology and structure design, defect engineering, etc. Herein, focusing on oxide and polyanionic cathode materials, a comprehensive and systematic review on emerging optimization strategies is provided by discussing representative studies of each. Corresponding fundamental principles, their applicable ranges, and common influences on properties are analyzed. Finally, the perspectives on the current impediments and future directions in the field are presented.

Atomically Dispersed Metal‐Based Catalysts for Zn–CO2 Batteries

Abstract: Rechargeable aqueous Zn–CO2 batteries show great promise in meeting severe environmental problems and energy crises due to their combination of CO2 utilization and energy output, as well as advantages of high theoretical energy density, abundant raw materials, and high safety. Developing high‐efficiency and stable CO2 reduction reaction (CO2RR) electrocatalysts is of critical importance for the promotion of this technology. Atomically dispersed metal‐based catalysts (ADMCs), with extremely high atom‐utilization efficiency, tunable coordination environments, and superior intrinsic catalytic activity, are emerging as promising candidates for Zn–CO2 batteries. Herein, some recent developments in atomically dispersed metal‐based catalysts for Zn–CO2 batteries are summarized, including transition metal and non‐transition metal sites. Moreover, various synthetic strategies, characterization methods, and the relationship between active site structures and CO2RR activity/Zn–CO2 battery performance are introduced. Finally, some challenges and perspectives are also proposed for the future development of ADMCs in Zn–CO2 batteries.

Embedding Metal–Organic Frameworks for the Design of Flexible Hybrid Supercapacitors by Electrospinning: Synthesis of Highly Graphitized Carbon Nanofibers Containing Metal Oxide Nanoparticles

Abstract: Electrospun carbonaceous fibers have emerged as promising electrode materials for application in energy storage devices. However, their relatively poor electrical conductivity (due to their amorphous carbon structures) and low capacitive performance lead to poor prospects for their further application. Herein, a universal synthesis of highly graphitized carbon nanofibers, containing various metal oxide nanoparticles (e.g., Fe2O3, NiO), by the pyrolysis of metal–organic framework (MOF)‐embedded electrospun nanofibers, is reported. The resulting carbon nanofibers exhibit large mesopore volumes, contain large quantities of Faradic metal oxide nanoparticles, and are highly graphitized. The fibers also have excellent mechanical flexibility, provide fast ion transfer characteristics, and a large pseudocapacitance combined with excellent electrical conductivity, leading to large specific capacitances. Consequently, asymmetric flexible hybrid supercapacitors assembled from Fe2O3‐embedded highly graphitized carbon nanofibers (FOCNF) and NiO‐embedded highly graphitized carbon nanofibers (NOCNF) exhibit a high energy density of 43.1 Wh kg−1 at a power density of 412.5 W kg−1 and possess excellent flexibility (capacitance retention of 94.4% at 180° bending and 96.2% at 30° twisting) with superior cycling stability. This strategy provides a new MOF‐based approach for the design and synthesis of multifunctional flexible carbonaceous materials and might lead to their further application in flexible energy storage devices.