Fused borophenes: A new family of superhard light-weight materials

The search of new superhard materials has received a strong impulse by industrial demands for low-cost alternatives to diamond and c-BN, such as metal borides. In this Letter we introduce a new family of superhard materials, “fused borophenes” (FBs), containing 2D boron layers that are interlinked to form a 3D network. These materials, identified through a high-throughput scan of BxC1−x structures, exhibit Vicker's hardness comparable to those of the best commercial metal borides. Due to their low formation enthalpies, FBs could be synthesized by high-temperature methods, starting from appropriate precursors, or through quenching of high-pressure phases.