Carbon-based transition metal chalcogenides for wearable sensors, energy storage, and photodetector applications

Niobium (Nb) and tantalum (Ta), transition metals with distinct physical and chemical properties, are highly attractive for applications in electrochemical energy storage (EES) devices. Their oxides, dichalcogenides, and MXenes demonstrate significant potential due to effective ion‐diffusion channels and high theoretical capacity. Particularly, Nb‐based dichalcogenides and MXenes offer enhanced electrochemical performance for lithium‐ion batteries (LIBs) and supercapacitors (SCs) applications because of their layered structure. However, the tendency of Nb chalcogenides and Nb‐MXene layers to aggregate or restack impedes electrolyte penetration, diminishing coulombic efficiency and capacity. Moreover, Nb‐ and Ta‐based oxides have intrinsically low electrical conductivity and a slow Li intercalation rate, challenging their application in energy storage devices. To address these issues, strategies such as hierarchical structuring, heteroatom doping, and the development of porous or nanoscale forms, as well as composites incorporating carbon or conductive polymers, have been explored. This review summarizes the impacts of various synthesis techniques, crystal structures, and morphological tunings on the electrochemical properties of Nb and Ta materials in LIBs and SCs and outlines the future directions for enhancing their performance in EES applications.

The dramatic environmental pollution and energy shortages have spurred internationally unprecedented interest in developing new energy technologies. Supercapacitors have emerged as a new class of green electrochemical devices for energy conversion and storage and are promising candidates for extensive applications. As a key component of supercapacitors, electrode materials are a crucial factor to the electrochemical performance based on its properties including surface area, pore structure, conductivity and surface functionalization. The well-designed synthesis strategies and conditions are usually fatal to tailor four mentioned properties. Due to the advantages of low cost, high specific surface area and conductivity, controllable microstructure, easy surface functionalization, remarkable chemical stability and outstanding electrolyte ion accessibility, porous carbon materials tailored through well-designed synthesis strategies and conditions, exhibit high energy density and power density as well as superb electrochemical cycling stability. In this review, we firstly provide a brief description of energy storage mechanisms for different types of electrode materials, followed by a comprehensive overview of recent advances in development of different carbon-based materials with activated carbon, carbon aerogels, carbon fiber, mesoporous carbon, carbon nanotube and graphene. Then we state the key parameters to evaluate the electrochemical properties, such as specific capacitance, energy density and power density, and also discuss the relationship between the influence parameters (e.g. surface area, pore structure, conductivity, and surface properties) and enhanced performances. Further, according to the research work of our group, we present a summary on the design, synthesis and applications in energy conversion and storage based on porous carbon materials, including carbons with different pore distributions (hierarchical porous carbon, porous carbon sphere, ultramicroporous carbon), functionalized porous carbon and porous carbon composite materials. In terms of carbons with different pore distributions, we list some characteristic synthetic methods (e.g. the self-template strategy for banana-peel-derived hierarchical porous carbon foams, the seeded synthetic strategy for phenolic-resin-derived porous carbon nanospheres and the solvothermal method for phloroglucinol-terephthaldehyde-derived ultramicroporous carbon nanoparticles), which can be concluded that micropores (especially ultramicropores) are electrochemically available for electrolyte ions because the solvation shell is squeezed through the pores less than the solvated ion size and such distortion reduces distance between the electrode surface and the ion center, while mesopores offer highly efficient pore channels for ion penetration and transport. In terms of functionalized porous carbon, we adopt the in situ synthesis approach to prepare nitrogen-doped carbons ( e.g. poly(1, 5-diaminonapthalene)-derived nitrogen-containing carbon microspheres and phenylenediamine-terephthalaldehyde-derived nitrogen-functionalized microporous carbon nanoparticles), which demonstrate that heteroatom doping, on the one hand, increases the surface wettability in the aqueous electrolyte to improve the mass transfer efficiency, and on the other hand, endows additional psedocapacitance for the electrode. In terms of porous carbon composite materials, we combine carbon-based materials with pseudocapacitive metal oxides (e.g. NiO and MnO2) for achieving high-performance supercapacitors, which is a wise choice to increase the energy density without sacrificing the high power capability. These strategies and methods provide new ideas to simple and highly efficient design of porous carbon materials and may be extendable to other systems such as metal or metal oxide materials. Additionally, the future trend of carbon based electrode materials for energy conversion and storage device is discussed. There are extensive applications outside the area of high-rate electrochemical energy storage, such as drug delivery, photonic crystals, adsorption and separation, and catalysis.

The increasing demand for energy and the reducing supply of conventional energy storage devices have inspired interest to design environmentally-friendly, abundant, and cheap materials for energy storage applications. Graphitic carbon nitride (gCN)-based hybrids have attracted research efforts due to their attractive properties, structures, and performance. In this respect, this chapter addresses the different hybrid gCN-based devices for energy storage applications. The supercapacitance efficiency of gCNs can be improved by incorporating carbon-based materials, metal oxides/hydroxides, or metal sulfides, which increase the surface area and active sites and facilitate the faradaic reaction. The pulverization and aggregation of electrodes and relatively low electrical conductivity demonstrate the major challenges for Li+ storage applications using gCNs. This chapter highlights the recent advances in the rational design of gCN-based devices for energy production and storage applications. This includes fabrication of gCN-hybrids with carbon materials, metal oxides, and metal sulfides for Li-ion batteries (LIBs), Li–S batteries (LSBs), and supercapacitors. The current challenges and future perspectives on gCN-based energy production devices are also discussed.

Over the past decade, carbon quantum dots (CQDs) and graphene quantum dots (GQDs) have emerged as the supreme category of zero‐dimensional (0D) carbonaceous nanostructures having potential applications in energy storage and optoelectronics devices. These zero‐dimensional carbon nanostructures have captivated excellent consideration and have ascended as a substitute to traditional metal‐based semiconductor QDs due to their intriguing estates like excellent photoluminescence, quantum yield, scalability, tuneable emission, biocompatibility, chemical inertness, and excellent hydrophilicity. These unique properties of zero‐dimensional carbon materials have inspired researchers to employ them in bioimaging, optoelectronic, catalytic, and energy storage applications. The last couple of years have perceived an incredible rise in the green synthetic strategies of carbon‐based QDs and their applications and this review familiarizes the reader with the current and significant progress in the synthesis of carbon‐based QDs/GQDs from various natural precursors with their quantum yields as well as intriguing applications in diverse fields. In addition, this communication not only delivers critical perceptions toward the development in the field of advanced energy devices but also highlights the advancements of these nanosized carbonaceous materials in the energy storage devices such as in supercapacitors and batteries. Also, it focuses on the broad scope of carbon nanomaterials and nanotechnology towards cutting‐edge research and expansion in the arena of energy storage applications of carbon‐based QDs.

Last developments in polymers for wearable energy storage devices

A review of transition metal chalcogenide/graphene nanocomposites for energy storage and conversion

The promising frontier for next-generation energy storage and clean energy production: A review on synthesis and applications of MXenes

Over the past decades, the development of porous materials has directly or indirectly affected industrial production methods. Metal-organic frameworks (MOFs) as an emerging class of porous materials exhibit some unique advantages, including controllable composition, a large surface area, high porosity, and so on. These attractive characteristics of MOFs have led to their potential applications in energy storage and conversion devices, drug delivery, adsorption and storage, sensors, and other areas. However, powdered MOFs have limited practical applications owing to poor processability, safety hazards from dust formation, and poor recyclability. In addition, the inherent micro/mesoporosities of MOFs also reduce the accessibility and diffusion kinetics for large molecules. To improve their processability for practical applications, MOFs are often deposited as MOF layers or films (i.e., MOF-coated composites) on supporting materials or are formed into 3D structured composites, such as aerogels and hydrogels. In this article, we review recent researches on these MOF composites, including their synthetic methods and potential applications in energy storage devices, heavy metal ion adsorption, and water purification. Finally, the future outlook and challenges associated with the large-scale fabrication of MOF-based composites for practical applications are discussed.

Chapter 9 - Energy storage properties of graphene nanofillers

Downsizing well-established materials to the nanoscale is a key route to novel functionalities, in particular if different functionalities are merged in hybrid nanomaterials. Hybrid carbon-based hierarchical nanostructures are particularly promising for electrochemical energy storage since they combine benefits of nanosize effects, enhanced electrical conductivity and integrity of bulk materials. We show that endohedral multiwalled carbon nanotubes (CNT) encapsulating high-capacity (here: conversion and alloying) electrode materials have a high potential for use in anode materials for lithium-ion batteries (LIB). There are two essential characteristics of filled CNT relevant for application in electrochemical energy storage: (1) rigid hollow cavities of the CNT provide upper limits for nanoparticles in their inner cavities which are both separated from the fillings of other CNT and protected against degradation. In particular, the CNT shells resist strong volume changes of encapsulates in response to electrochemical cycling, which in conventional conversion and alloying materials hinders application in energy storage devices. (2) Carbon mantles ensure electrical contact to the active material as they are unaffected by potential cracks of the encapsulate and form a stable conductive network in the electrode compound. Our studies confirm that encapsulates are electrochemically active and can achieve full theoretical reversible capacity. The results imply that encapsulating nanostructures inside CNT can provide a route to new high-performance nanocomposite anode materials for LIB.

Resorcinol-formaldehyde based carbon aerogel: Preparation, structure and applications in energy storage devices

4.12 - One-Dimensional Inorganic Nanomaterials for Energy Storage and Production

Investigating the synergistic characteristics of air processable CsPbIBr₂ perovskite electrodes for solar cell and energy storage applications

Conductive forms of MoS2 are important emerging 2D materials due to their unique combination of properties such as high electrical conductivity, availability of active sites in edge and basal planes for catalytic activity and expanded interlayer distances. Consequently, there has been a drive to find synthetic routes toward conductive forms of MoS2. Naturally occurring or synthetically grown semiconducting 2H-MoS2 can either be converted into metallic 1T-MoS2, or various dopants may be introduced to modulate the electronic band gap of the 2H-MoS2 phase and increase its conductivity. Chemical and electrochemical intercalation methods, hydrothermal and solvothermal processes, and chemical vapor deposition have all been developed to synthesize conductive MoS2. Conductive MoS2 finds applications in energy storage devices, electrocatalytic reactions, and sensors. Here, we summarize a detailed understanding of the atomic structure and electronic properties of conductive MoS2 which is crucial for its applications. We also discuss various fabrication methods that have been previously reported along with their advantages and disadvantages. Finally, we will give an overview of current trends in different applications in energy storage and electrocatalytic reactions in order to help researchers to further explore the applications of conductive MoS2.

Electrochemistry of 2D-materials for the remediation of environmental pollutants and alternative energy storage/conversion materials and devices, a comprehensive review