Solution-Processed Two-Dimensional Metal Dichalcogenide-Based Nanomaterials for Energy Storage and Conversion.

Review: [167 refs.

Since the initial MXenes were discovered in 2011, several MXene compositions constructed using combinations of various transition metals have been developed. MXenes are ideal candidates for different applications in energy conversion and storage, because of their unique and interesting characteristics, which included good electrical conductivity, hydrophilicity, and simplicity of large-scale synthesis. Herein, we study the current developments in two-dimensional (2D) MXene nanosheets for energy storage and conversion technologies. First, we discuss the introduction to energy storage and conversion devices. Later, we emphasized on 2D MXenes and some specific properties of MXenes. Subsequently, research advances in MXene-based electrode materials for energy storage such as supercapacitors and rechargeable batteries is summarized. We provide the relevant energy storage processes, common challenges, and potential approaches to an acceptable solution for 2D MXene-based energy storage. In addition, recent advances for MXenes used in energy conversion devices like solar cells, fuel cells and catalysis is also summarized. Finally, the future prospective of growing MXene-based energy conversion and storage are highlighted.

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.

Recent advances in the synthesis and modification of carbon-based 2D materials for application in energy conversion and storage

Graphene oxide (GO), a single sheet of graphite oxide, has shown its potential applications in electrochemical energy storage and conversion devices as a result of its remarkable properties, such as large surface area, appropriate mechanical stability, and tunability of electrical as well as optical properties. Furthermore, the presence of hydrophilic functionalities on basal and edge planes induces other relevant properties, which make GO an attractive material for electrochemical applications. On account of having structural diversity and enhanced overall crucial properties, GO and its composites have attracted much attention in contribution of energy storage devices, such as batteries, supercapacitors, and energy conversion devices, such as fuel cells and water electrolyzers. Previous review reports demonstrated the individual applications of GO or reduced graphene oxide (RGO) in either of the electrochemical energy devices. The present review highlights all of the recent developments of GO and RGO in both the energy storage and conversion devices along with the recent synthesis methodologies, which are crucial to unveil all of the outperforming properties of GO and RGO. The transition in the synthesis of GO with various chemical methods, including the Brodie and improved Hummers methods, to electrochemical approaches have been described with recent developments as well as highlights of the importance of electrochemical energy in the synthesis of GO. Utilization of GO in energy storage applications predominantly as electrodes and electrolytes and membranes in energy conversion devices further diversify its multiple applicability as a result of its variable functional properties. Multiple energy storage devices, such as Li-ion, Na-ion, Li–S, and flow batteries and supercapacitors, have shown the enhanced performance with the introduction of GO and RGO. Furthermore, GO has also shown excellent applicability in energy conversion devices, such as proton-exchange membrane fuel cells, methanol fuel cells, and water electrolyzers, which have also been discussed in this review. This review further summarizes the recent synthesis methodologies of GO and RGO along with their importance in electrochemical energy devices with allied challenges and future perspectives.

Multiscale architected porous materials for renewable energy conversion and storage

Recent application of carbon nanotubes in energy storage and conversion devices

Prospects of MXene-based nanocomposites: Properties, synthesis techniques, and their applications in electrochemical energy conversion and storage devices

Prussian blue, its analogues and their derived materials for electrochemical energy storage and conversion

The development of high-performance electrochemical energy storage and conversion devices, including supercapacitors, lithium-ion batteries, and fuel cells, is an important step on the road to alternative energy technologies. Carbon-containing nanomaterials (CCNMs), defined here as pure carbon materials and carbon/metal (oxide, hydroxide) hybrids with structural features on the nanometer scale, show potential application in such devices. Because of their pronounced electrochemical activity, high chemical and thermal stability and low cost, researchers are interested in CCNMs to serve as electrodes in energy-related devices. Various all-carbon materials are candidates for electrochemical energy storage and conversion devices. Furthermore, carbon-based hybrid materials, which consist of a carbon component with metal oxide- or metal hydroxide-based nanostructures, offer the opportunity to combine the attractive properties of these two components and tune the behavior of the resulting materials. As such, the design and synthesis of CCNMs provide an attractive route for the construction of high-performance electrode materials. Studies in these areas have revealed that both the composition and the fabrication protocol employed in preparing CCNMs influence the morphology and microstructure of the resulting material and its electrochemical performance. Consequently, researchers have developed several synthesis strategies, including hard-templated, soft-templated, and template-free synthesis of CCNMs. In this Account, we focus on recent advances in the controlled synthesis of such CCNMs and the potential of the resulting materials for energy storage or conversion applications. The Account is divided into four major categories based on the carbon precursor employed in the synthesis: low molecular weight organic or organometallic molecules, hyperbranched or cross-linked polymers consisting of aromatic subunits, self-assembling discotic molecules, and graphenes. In each case, we highlight representative examples of CCNMs with both new nanostructures and electrochemical performance suitable for energy storage or conversion applications. In addition, this Account provides an overall perspective on the current state of efforts aimed at the controlled synthesis of CCNMs and identifies some of the remaining challenges.

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

Electrochemical energy storage and conversion devices are regarded as one of the most attractive technologies to overcome the crisis of fossil fuel exhaustion and the global pollution. The key to advance these technologies is to explore suitable materials with various advantages of good performance, such as high stability, low cost, and environmental friendliness. The emerging twodimensional (2D) molybdenum sulfide (MoS2) has shown vast potential for renewable energy storage and conversion applications, due to its intriguing physicochemical properties. Nevertheless, several issues handicap the commercial application of MoS2, including rapid structure degradation, low electrical conductivity, and sluggish charge transfer kinetics. Therefore, scientific research and breakthroughs are highly desirable to address these issues and satisfy the requirements for practical use.

Recent advances of two-dimensional transition metal nitrides for energy storage and conversion applications

Recently, there has been a dramatic increase in research of nanoscale materials for energy conversion and storage applications due to several advantageous features such as high surface areas, short transport distances, novel optical phenomena, and tunable material properties. However, with these benefits come challenges. In particular, the ability to precisely control the properties of surfaces and heterogeneous interfaces at the nanoscale limits the performance of many of these devices, and requires novel approaches. This problem becomes increasingly important as dimensions decrease, as the surface-to-volume ratios contiunally increase with decreasing feature size. Semiconductor nanowires (NWs) posses several advantages for energy conversion devices owing to their high surface areas, tunable compositions, and efficient charge transport properties [1]. However, precise control of surfaces and interfacial properties is crucial to maximize charge-transfer efficiency across the interfaces between NWs and the surrounding device components, while minimizing undesirable side reactions and recombination losses. One technique that has been increasingly explored for surface and interfacial engineering of nanostructured energy conversion and storage devices is Atomic Layer Deposition (ALD). This gas-phase process allows for highly conformal deposition of a wide variety of materials with sub-nm precision in material thickness and tunable chemical composition. By coating the surfaces of NWs with ALD, core-shell structures can be fabricated with atomic-scale control. This combination of conformality and thickness control facilitates precise tuning of the electronic, optical, thermal, and chemical properties of nanowire surface to optimize their interfaces in energy conversion devices. This talk will present several examples of using ALD to fabricate highly-controlled core-shell for energy conversion and storage devices, with an emphasis on solar energy applications. Examples include quantum-dot sensitized nanowires [2], earth abundant core-shell NW photovoltaics at the singe nanowire and array level [3], and coating of nanowire surfaces with passivation layers and co-catalysts for photoelectrochemical water splitting [4-5]. Additionally, the use of ALD for precise control of heterogeneous interfaces in hierarchical nanomaterial synthesis will be presented. The importance of fully understanding ALD surface chemistry will be discussed from a theoretical and experimental perspective. The talk will conclude with a perspective on future directions and challenges for widespread commercial adaption of these technologies.

Synthesis and nano-engineering of MXenes for energy conversion and storage applications: Recent advances and perspectives