Progress and Perspectives on Covalent‐Organic Frameworks (COFs) and Composites for Various Energy Applications

Abstract

Covalent‐organic frameworks (COFs), being a new member of the crystalline porous materials family, have emerged as important materials for energy storage/conversion/generation devices. They possess high surface areas, ordered micro/mesopores, designable structures and an ability to precisely control electro‐active groups in their pores, which broaden their application window. Thanks to their low weight density, long range crystallinity, reticular nature and tunable synthesis approach towards two and three dimensional (2D and 3D) networks, they have been found suitable for a range of challenging electrochemical applications. Our review focuses on the progress made on the design, synthesis and structure of COFs and their composites for various energy applications, such as metal‐ion batteries, supercapacitors, water‐splitting and solar cells. Additionally, attempts have been made to correlate the structural and mechanistic characteristics of COFs with their applications.

Recent Development of Morphology‐Controlled Hybrid Nanomaterials for Triboelectric Nanogenerator: A Review

“…The COFs are extremely simple to change and can be customize. Due to their higher stability nature and porosity, it is used in a broad range of applications like gas adsorption, catalysis energy conversion, energy storage, and energy harvesting [233b] . So far, COFs have been used in frequently to construct devices that directly transform mechanical energy into electrical energy.…”

Covalent Organic Frameworks (COFs)/MXenes Heterostructures for Electrochemical Energy Storage

“…Recently, MXenes have gained wide attention in the energy storage owing to their metallic conductivity and redox-active surfaces, however, a narrow operational voltage limits their capacity and energy density. Similarly, COFs have been used for the energy storage thanks to their high surface area, porosity, processability, and chemical and mechanical integrity . However, poor capacity results from the absence of metal redox centers and limited conductivity.…”

“…Similarly, COFs have been used for the energy storage thanks to their high surface area, porosity, processability, and chemical and mechanical integrity. 19 However, poor capacity results from the absence of metal redox centers and limited conductivity. Pairing MXenes and COFs in a single electrode could be a viable strategy to take advantage of both materials and maximize the energy storage capability.…”

Construction of a Cu-Based Metal–Organic Framework by Employing a Mixed-Ligand Strategy and Its Facile Conversion into Nanofibrous CuO for Electrochemical Energy Storage Applications

“…Because of continuous economic growth, there is a high demand for energy resources to develop new-generation electrochemical conversion and energy storage devices. , In recent times, supercapacitors have achieved significant attention among other charge-storage devices thanks to their fascinating characteristics involving fast charge–discharge rate, high power density, and long-time cyclic stability. , It has been investigated whether their capacitance can be controlled by optimizing the electrochemical activity, morphology, mechanical/chemical stability, and conductivity of electrode materials . Therefore, it is strongly recommended that advanced materials be designed and developed to fulfill the necessities of high energy supply. , In recent times, carbon-based conducting materials and redox-active transition-metal oxides have gained tremendous attention in achieving superior supercapacitor performance. − In particular, metal oxides have attracted great consideration as fascinating supercapacitor materials owing to their high thermal/chemical stability, low-cost preparation, controlled chemical/physical properties, and high scalability. − However, the majority of the metal oxides suffer from low electrical conductivity and poor cyclic stability, which restricts their wide application in high-energy-density-based supercapacitors. , Generally, transition-metal oxides are extensively investigated materials that demonstrate pseudocapacitive characteristics to store charge utilizing reversible faradaic redox reactions . To develop a pseudocapacitor with high capacitance, it is essential to fabricate nanostructured metal oxides with large surface area and suitable morphology and porosity. , Among the transition-metal oxides, CuO has been recognized as one of the most encouraging energy storage materials because of its exciting physicochemical characteristics, environmental friendliness, natural abundance, nontoxicity, and cost-effectiveness. , Consequently, various strategies have been employed for their improved synthesis, such as sonochemical, electrodeposition, hydrothermal, and microwave-assisted synthesis. − However, many of these techniques suffer from reproducibility and scalability issues. − Also, metal oxides usually show significant volume expansion during charging–discharging, which results in poor rate ability and insufficient cyclic stability.…”