LAUSR

Two-dimensional (2D) carbon nitrides (CxNy) have great potential in advanced fields such as energy harvest and storage. We report a novel 2D CxNy, C6N3, comprising sp-N and sp2-C atoms. Density functional theory calculations indicate that electronically, thermally, and dynamically stable C6N3 is metallic even when cut into very narrow nanoribbons. C6N3 adsorbed single atoms of 3d, 4d, and 5d transition metals to fabricate single-atom catalysts (SACs) for an electrocatalytic hydrogen evolution reaction (HER). Among all SACs studied, Ti-, Cr-, Zr-, and Hf-embedded C6N3 had excellent overall performance including promising stability, moderate binding strength of H and H2, and good electrical conductivity. Our results suggest a novel C6N3 with an sp-N skeleton that has great potential for HER. More investigations are needed to further understand the properties and applications of C6N3 in other fields.