Atomically thin non-layered nanomaterials for energy storage and conversion

Abstract

After the discovery of graphene, two-dimensional nanomaterials with atomic thickness and large lateral size have attracted tremendous research interest due to their high specific surface areas, exotic electronic structures, and fascinating physical and chemical properties. Even though recent studies are mainly focused on atomically thin nanomaterials with layered structures due to their easy preparation and characterization, the investigation of non-layered nanomaterials is also proceeding as new types of ultrathin nanostructures are constantly being created, such as metals, metal oxides, metal chalcogenides, some transition metal dichalcogenides, and perovskites. Here in this review, we comprehensively summarize the preparation methods for atomically thin non-layered nanomaterials, study their exotic electronic structures, introduce electronic-structure manipulation strategies, and provide an overview of their applications in energy storage and conversion, with particular emphasis on lithium-ion batteries, sodium-ion batteries, catalysis of hydrogen evolution, oxygen evolution, CO reduction, CO oxidation reactions, etc. The central theme of this review is to provide correlation among the materials synthesis, structural and electronic properties, and their major applications. Finally, based on current research progress, we propose future directions yet to be explored for enhanced properties and novel functionalities in practical applications.

Electrospun N‐Doped Porous Carbon Nanofibers Incorporated with NiO Nanoparticles as Free‐Standing Film Electrodes for High‐Performance Supercapacitors and CO2 Capture

“…The resulting TMOs/CNF composite materials exhibited electrochemical performance in supercapacitors and electrocatalysis. It has been demonstrated that NiO/Co 3 O 4 NPs distributed in both internal and surface of CNF exhibit excellent electrochemical supercapacitive performances. Lou and co-workers prepared flexible films derived from electrospun CNF incorporated with Co 3 O 4 hollow NPs, as self-supported electrodes, which exhibited high specific capacitance and excellent cycling stability.…”

Honeycomb‐Inspired Heterogeneous Bimetallic Co–Mo Oxide Nanoarchitectures for High‐Rate Electrochemical Lithium Storage

“…Rational design of nanostructured electrode nanomaterials, which possess the properties to enhance reaction kinetics, accommodate structural strains, facilitate rapid mass transport paths, and enlarge ion storage sites and interfaces, have been shown to be an exciting approach to boost the performance of energy storage devices . Unfortunately, some electrochemically favorable nanostructures lose their structural integrity during cycles and finally result in sluggish electrochemical reactions and rapid decay of capacity, particularly at high rates . Therefore, how to maintain structurally stable nanostructures with enhanced electrochemical performances is another research target for high‐rate energy storage devices …”

“…It has been reported that 2D materials have demonstrated plenty of advantages compared to the corresponding bulk materials . In the honeycomb‐inspired microspheres, the basic constitutional nanostructures are 2D CoMoO x nanosheets.…”

Manipulating 2D Few‐Layer Metal Sulfides as Anode Towards Enhanced Sodium‐Ion Batteries

“…To take advantage of the intrinsic structures of different metal sulfides, two basic strategies, 'top-down' and 'bottom-up' methods, have been utilized to prepare ultrathin 2D-MSs. [95] The layered MSs have in-plane chemical bonds but weak outof-plane van der Waals bonds, which mean the dimension of the bulky MSs can be reduced as 2D materials. Therefore, the top-down method, such as mechanical exfoliation, liquid exfoliation, and chemical deposition, are able to easily produce single-or few-layer nanosheets from bulky MSs, such as MoS 2 , VS x , SnS 2 , and WS 2 .…”