Effect of d-block metals (M = Ti, Zr, Hf) decorated fullerenes M@C60 as sensor nanostructured materials for volatile organic compounds (VOCs): Approach from computational study

Abstract

Volatile organic compounds (VOCs) are organic substances that readily evaporate into the atmosphere at room temperature, posing a regular exposure risk to humans. These compounds are associated with various environmental issues, including stratospheric ozone layer depletion, ground-level smog formation, climate change, sick building syndrome, plant decay, atmospheric toxicity, and potential carcinogenic effects on human health. In this study, we utilized ab-initio calculations based on density functional theory (DFT) at the B3LYP-GD3(BJ)/Def2-SVP method to examine how the functionalization of C60 fullerene with Ti, Hf, and Zr transition metals affects its sensing capabilities for volatile organic compounds, specifically methylcyclopentane (MCP), propanone (PPN), and benzene (BZN). The maximum adsorption energy of the transition metal decorated nanocages was recorded at 73.689 kcal/mol corresponding to PPN_Zr@C60 in tandem with the least energy gaps indicating higher conductivity of the PPN_Zr@C60 nanocage with the short bond distance of 1.929 Å for (Zr – O) interaction. The adsorption energy value proposes the adsorption of the volatile organic compound on the Ti, Hf, and Zr transition metal decorated C60 fullerene following the order BZN_Hf@C60 < BZN_Ti@C60 < PPN_Zr@C60. The studied systems possess a relatively high desorption time and they follow the increasing trend – BZN_Hf@C60 < MCP_Hf@C60 < MCP_Zr@C60 < MCP_Ti@C60 < PPN_Hf@C60 < BZN_Zr@C60 < BZN_Ti@C60 < PPN_Ti@C60 < PPN_Zr@C60. The results account that Zr@C60 possesses the highest desorption time and adsorption energy, hence more apposite for detecting the studied VOCs. It also divulges in Hf@C60 contains the least desorption time and least adsorption energy, therefore is not suitable for the detection as it basically portrays the least affinity for the adsorbed VOCs molecule. These results indicate that the VOC transition metal functionalized Ti@C60 and the Zr@C60 are excellent sensors for the effective detection and adsorption of volatile organic compounds which may be useful for environmental protection and the safeguard of human health.