Designing 2D Fullerene Networks from C₇₀: A Stable and Synthesizable Platform for Electronic Band Engineering

Two-dimensional (2D) fullerene networks, assembled through covalent bonding of molecular fullerene building blocks, represent a rapidly emerging class of carbon-based nanomaterials with highly tunable topological structures and electronic properties. Here, we report the theoretical prediction of three 2D C70 crystalline phases, two quasi-tetragonal phases (qTP1 and qTP2) and a quasi-hexagonal phase (qHP), formed through distinct covalent connections along the minor or major axis of ellipsoidal C70 molecules. Comprehensive stability assessments confirm their thermodynamic, dynamic, and mechanical robustness, supported by feasible synthesis pathways analogous to those employed for the experimentally realized 2D C60 networks. The qTP2 phase is identified as a rare semimetallic carbon network with intrinsic magnetism arising from sp2 carbon atoms, while qTP1 and qHP possess ultranarrow band gaps. Our findings establish 2D C70 as a versatile platform for engineering low-dimensional carbon-based quantum materials.