Replication of Mechanochemical Syntheses of γ-Graphyne from Calcium Carbide Fails to Produce the Claimed Product

Several recent articles by Cui and coworkers claim syntheses of γ-graphyne, a novel sp2/sp1 allotrope of carbon, directly from calcium carbide. Here, we describe the replication of the key experiments from this series of articles. We did not observe the formation of γ-graphyne under the reported conditions. The characterization data from our replications are partially consistent with the results reported by Cui. However, we show that the claimed experiments produce only heavily contaminated, amorphous chars with no detectable sp1 carbons.