Fundament and Application of Graphdiyne in Electrochemical Energy.

The artificial synthesis of graphdiyne (GDY) in 2010 successfully fills the blank of low temperature preparation of all-carbon allotropes. GDY is an emerging two-dimensional (2D) planar carbon material composed of benzene rings moieties (sp2 carbon atoms), butadiyne (sp carbon atoms) linkers, and well dispersed electron-rich cavities, forming a large π-conjunction structure. GDY has attracted increasing attention in many fields. GDY is the first carbon material with both 2D fast transfer channels for electrons and 3D channels for ions. The 2D electron-rich all-carbon nature endows GDY with considerable conductivity and tunable electronic properties, and the in-plane cavities give it intrinsic selectivity and accessibility for electrochemically active metal ions. In addition, its easy preparation under mild conditions well complements the disadvantages of the traditional sp2-hybridized carbon materials (carbon nanotubes, graphene, and graphite) in the highly efficient synthesis and processing for potential electrochemical applications. As an all-carbon material, the unique advantages of GDY in both structure and preparation match well the urgent demands in key materials for solving many challenging problems in recent electrochemical areas and beyond. During the last decade since the first preparation of GDY, it has already achieved much enlightening and creative progress in both fundamental scientific research and forward-looking applications. This Account is intended not to summarize all this progress in preparation and applications but to outline some newly reported interesting phenomena in both high-quality preparation and electrochemical applications. This Account mainly discusses the recent progress in electrochemical applications: (i) constructing new concepts and new functions in electrochemical interfaces for realizing highly active electrochemical catalysts in the fields of water splitting and oxygen reduction reaction and (ii) building a highly stable conductive network and electrochemical interface for reversible energy storage. In the field of electrochemical catalysis, based on current studies of structural advantages and superior performance, atomic catalysis with metal atoms anchored in GDY is encouraging, owing to the desirable immobilizing capability of electron-rich dialkyne cavities toward metal atoms and corresponding electron transfer. For high-energy batteries, the in situ growth of the all-carbon GDY on the various battery electrodes shows great promise for solving key practical problems (safety, long lifespan, high power), which are ascribed to weak interfacial stability. In addition, the perspective application of GDY to broader interfacial modifications is described, bringing new choices for solving the interfacial challenges in various energy storage devices.