Benzonitrile-driven discharge of potassium-intercalated carbon allotropes

In this work we performed a comprehensive investigation, exploring the reduction of synthetic carbon allotropes (SCAs) via alkali metal intercalation. Carbon nanotubes (CNTs), carbon nano-onions (CNOs), and fullerenes (C 60 &C 70 ) were employed, focusing on post-intercalation electron transfer efficiency and mass transport dynamics with benzonitrile (PhCN). Our study revealed the feasibility of discharging residual negative charges in all allotropes, exhibiting different electron transfer ratios (ETR) dependent on morphological factors. Notably, CNT length played a crucial role, shorter HiPco nanotubes displayed a significantly higher ETR (55%) compared to longer arc discharge nanotubes (15%), highlighting the influence of nanotube length on intercalation kinetics. Further investigation into CNOs unveiled a relatively high ETR of 80% for untreated CNOs and a low ratio of 24% for oxidized onions, underlining the critical role of size distribution and surface chemistry. Inner shell entrapment of potassium reduces accessibility in CNOs, as confirmed by TGA-MS and XPS experiments. Our analysis underscored the impact of disparate electron affinities and molecular structures on electron transfer dynamics, as seen in our fulleride analysis, where reversible electron uptake from fullerides to solvent occurred, more pronounced for C 60 than C 70 . Overall, our findings demonstrated that CNTs and CNOs share similar mechanisms with graphenides, however, mass transport is limited by potassium accessibility. In contrast, molecular fullerenes exhibit distinct behavior due to competitive redox processes. Additionally, our investigation highlighted the utility of PhCN treatment in facilitating the recovery of pristine materials and mitigating undesired side functionalization post-exposure to moisture, thereby enabling the protocol's generalization across various SCAs.