Superconductivity Induced by Element Doping in C 48 Fullerene at Ambient Pressure

To investigate the superconducting potential of cage-type carbon compounds under ambient pressure, a pristine all-carbon C48 fullerene structure is designed and doped with various elements. By optimizing the occupancy of group IA, IIA, and IIIA elements at different sites within the C48 framework, we have obtained both stable metallic M2C24 (M = Li, Na, Mg, Al, Ga, and In) and HC24 structures. First-principles calculations demonstrate that metal atoms, serving as electron donors, can induce a semiconductor-to-metal transition in the C24 clathrate, while preserving high structural rigidity with a Vickers hardness exceeding 25 GPa. Further analysis of the superconducting properties reveals that the enhanced electronic state density at the Fermi level, driven by the vibration of the rigid carbon framework and elemental doping, enables Li2C24 to exhibit a superconducting transition temperature (Tc) of 12.71 K at ambient pressure. Similarly, the doping of non-metallic hydrogen effectively tunes HC24 into a superconductor with a Tc of 8.39 K. This study deepens the understanding of superconductivity in carbon cage compounds and opens new avenues for realizing high-temperature superconductors through hole doping and other modulation strategies.