Hydrogen-bonded organic frameworks and their derived materials for electrochemical energy storage and conversion

To satisfy the emergency demand of clean and renewable energy sources, developing highly efficient electrochemical energy storage and conversion technologies, such as rechargeable batteries, electrochemical capacitors, electrolyzers, and fuel cells, has become one of the greatest assignments for the sustainable development of society. Despite their different working principles, the two electrodes (cathode and anode), where the major electrochemical processes take place, such as charge storage in batteries/capacitors and electrocatalytic reactions in electrolyzers/fuel cells, are the key components for these electrochemical devices. Consequently, the design and construction of high-performance electrode materials has been a primary quest for the development of future electrochemical energy-related technologies. As a new class of porous materials, hydrogen-bonded organic frameworks (HOFs) have generated tremendous interests from researchers in widespread areas. Since most H-bonding interactions are essentially weak, flexible, and of low directionality, the morphology and structure of HOFs can be easily modulated depending on the precursors and synthesis solvents or conditions. In addition, the remarkably high porosity with large specific area and abundant functional groups endows the HOFs with rapid ion transport channels, specific ion sieving, considerable electrochemical active area, and highly exposed catalytic active sites. These features trigger extensive research interest to explore HOFs and their derivatives for electrochemical energy storage and conversion. Nevertheless, the electrochemical instability of hydrogen bonding and low electronic conductivity hampers their adaptation as electrode materials and electrocatalysts. To solve these issues, researchers have proposed some feasible schemes such as utilizing multiple hydrogen bonds and changing the electrolyte. In addition, converting HOFs into HOF-derived materials such as metal compounds, carbonaceous materials, or their composites has also been extensively investigated as alternative methods. These HOFs derivatives usually exhibit remarkable advantages originating from their microstructures or nanostructures, showing great potential in electrochemical energy related technologies. From this perspective, we summarized the latest developments of pristine HOFs and HOFs-derived materials as the electrodes or catalysts for electrochemical applications such as rechargeable batteries, electrochemical supercapacitors and electrocatalysis. We aim to provide an overview for this highly interdisciplinary area and discuss the significant breakthroughs that HOFs-related materials have brought to the field of electrochemical energy storage and conversion. The effects of morphology, structure and composition of these promising HOFs related materials on the electrochemical applications are systemically discussed. By highlighting the advantages and challenges of each class of materials for different applications, we hope to shed some light on the future development of HOFs related materials in the electrochemical applications.