A Comparative DFT study on the effect of transition metals (Ru–Ag) on zero-dimensional fullerene and one-dimensional carbon nanotube

The development of low-dimensional materials has driven significant interest in engineering novel nanostructures with desired properties. In this work, a theoretical investigation based on Density Functional Theory (DFT) is employed to understand the effects of Transition Metal (TM) dopants — Ru, Rh, Pd, and Ag on zero-dimensional carbon fullerene (C[Formula: see text] and one-dimensional Carbon Nanotube (CNT) structures. The comparative analyses reveal that TM doping significantly influences both fullerene and nanotube systems. Our results demonstrate that TM doping leads to notable changes in both systems. Among all configurations, Ru-doped fullerene (CF_Ru) and nanotube (CNT_Ru) exhibit the highest structural stability with binding energies of –7.526[Formula: see text]eV and –7.071[Formula: see text]eV, respectively. These structures also show an increase in average bond length (1.5192 Å for CF_Ru and 1.5019 Å for CNT_Ru), indicating an expanded surface area beneficial for sensing applications. Furthermore, all doped and pristine structures, except for pristine nanotube and Pd-doped fullerene, exhibit no imaginary frequencies in the IR spectrum, confirming their thermodynamic viability. From an electronic perspective, Ru-doped structures exhibit increased HOMO-LUMO gaps (1.946[Formula: see text]eV for CF_Ru and 1.986[Formula: see text]eV for CNT_Ru) and favorable dipole moments (4.191 Debye and 2.406 Debye), implying enhanced electronic reactivity and charge redistribution. Thermodynamic parameters such as Gibbs free energy ([Formula: see text][Formula: see text]eV for CF_Ru) and enthalpy ([Formula: see text][Formula: see text]eV) further support the spontaneous and stable nature of these Ru-doped structures. Based on these findings, Ru-doped fullerene and nanotube structures emerge as the most promising candidates for applications in semiconductor technology and nanoscale sensing devices.