Agradecimentos: Portions of the paper were developed from the thesis of C.M.B. Support for the University of Texas at Dallas was from the Office of Naval Research grant N00014-22-1-2569, the Air Force Office of Scientific Research grant FA9550-21-0455, and the Robert A Welch Foundation grant AT-0029. V.O.R. acknowledges funding from the U.S. Department of Energy (DE-SC0022100). We thank the NSF for funding through GRFP Award #1937968 to C.M.B. and GRFP Award #1451075 to W.B.M., Y.G. and E.G. acknowledge support from the Supercomputing Center of Wuhan University. Support for the University of Campinas was from Brazilian agencies CNPq (Grants #303284/2021-8 and #310052/2019-0) and the São Paulo Research Foundation (grants #2020/02044-9, #2023/02651-0, and #2013/08293-7) and by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil - Finance Code 001. A.F.F. thanks the computing resources and assistance of the John David Rogers Computing Center at the Institute of Physics Gleb Wataghin of the University of Campinas. L.A.R.J. acknowledges financial support from Brazilian agencies CNPq (350176/2022-1) and FAPDF (00193.00001247/2021-20) and computational support from LOBOC and CENAPAD-SP. Two Australian Synchrotron Beamline Funding Grants (AS231/SAXS/19742 and AS232/SAXS/20333) helped enable this work. Correspondence and requests for materials should be addressed to vor2@case.edu and ray.baughman@utdallas.edu. Ver menos

Abstract: The highest sheet symmetry form of graphyne, with one triple bond between each neighboring hexagon in graphene, irreversibly transforms exothermically at ambient pressure and low temperatures into a nongraphitic, planar- sheet, zero- bandgap phase consisting of intrasheet- bonded sp2 carbons. The synthesis of this sp2 carbon phase is demonstrated, and other carbon phases are described for possible future synthesis from graphyne without breaking graphyne bonds. While measurements and theory indicate that the reacting graphyne becomes nonplanar because of sheet wrinkling produced by dimensional mismatch between reacted and nonreacted sheet regions, sheet planarity is regained when the reaction is complete. Although the observed elimination of triple bonds to make parallel planar sp2 carbon sheets likely requires ordered transformation within each sheet, diffraction data for reacted multisheet stacks indicate that the relative lateral positions of neighboring sheets are disordered, as predicted, since no crystalline diffraction peak (other than for the intersheet spacing) is observed Ver menos