Metal cyanamides: Open-framework structure and energy conversion/storage applications

Metal cyanamides are an emerging class of functional materials with potential applications in sustainable energy conversion and storage technologies such as catalysis, supercapacitors, photoluminescence and next-gen batteries. The [NCN]2− as the anion, which is isolobal with [O]2− endows metal cyanamides with similar physicochemical properties as oxides and chalcogenides. Whereas the unique quasi-linear structure and electronic resonance between [NCN]2− and [N–CN]2− of [NCN] entity bring out superior properties beyond oxides and chalcogenides. In this review, we present research status, challenges, and the recent striking progress on the metal cyanamides in the synthesis and applications. Specifically, the characteristic structures, physicochemical properties, synthetic methods with corresponding merits/demerits and latest applications in energy conversion and storage of cyanamides are summarized. The detailed outlooks for the new compounds design, morphology manipulation and potential applications are also exhibited.