Engineering Bilayer MoS₂ with Moiré-Dopant Synergy for Advanced Supercapacitor Electrodes

Synergistic integration of atomic-scale doping and Moiré superlattices opens up new possibilities for manipulating the electrical characteristics of two-dimensional (2D) materials. Here, we report the first thorough first-principles investigation of site-specific chemical doping-based quantum capacitance (C_Q) modulation in Moiré-patterned bilayer MoS₂ (mBL-MoS₂). Periodic potential fluctuations caused by a 21.79° interlayer twist change the density of states close to the Fermi level. By performing transition-metal-site substitution (Mo → Nb) and chalcogen-site substitution (S → Se), further improvements are achieved. Nb doping, which induces a semiconductor-to-metal transition, greatly enhances electronic delocalization and quantum capacitance, whereas Se doping has a comparatively smaller impact owing to its isoelectronic nature with S. The structural and electronic tunability of these systems is confirmed by a comprehensive analysis that includes electronic structure, differential and integral C_Q calculations, electron localization function (ELF) mapping, Bader charge analysis, phonon stability, and work function evaluation. The superior charge storage capacity of Nb-doped mBL-MoS₂ in the low-bias domain is demonstrated by benchmarking against other 2D materials. These results show how Moiré engineering and chemical doping can work together to create a new design framework for C_Q-dominated supercapacitor electrodes.