Superhard porous carbon crystals derived from nanoporous ice frameworks

Porous carbon crystals are of great interest due to their high surface area and tunable porosity, which endow them with superior properties for a range of applications. The discovery of novel porous carbon architectures, therefore, holds both scientific and practical value. In this study, we propose twenty porous carbon crystals designed by analogy with nanoporous ice frameworks following the "ice-carbon" strategy. Among these, thirteen are reported for the first time, highlighting the effectiveness of this approach for predicting new carbon allotropes. The dynamic and mechanical stabilities of the proposed structures are confirmed through phonon spectrum analysis and elastic constant calculations, respectively. Importantly, these allotropes are energetically more favorable than experimentally synthesized T-carbon, suggesting their potential for experimental realization. Notably, fifteen of the twenty structures are classified as superhard materials, with Vickers hardness exceeding 40 GPa. Among them, four structures (PC-T-5.6.8, PC-O-4.6.8, PC-O-5.8, and PC-O-5.6.8 with the hardness values of 66.77, 65.63, 73.70, and 68.98 GPa, respectively) surpass the hardness of cubic boron nitride. Furthermore, all twenty porous carbons are identified as semiconductors with bandgaps ranging from 1.54 to 3.66 eV. Combining superhard character with high porosity, these superhard porous carbon materials show strong potential for applications in aerospace materials, battery components, catalysis, and photodetectors.