Exploring porphyrins induced carbon nanocone TM-PICNC (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) as a highly sensitive sensor for CO2 gas detection in presence O2 and H2O molecules: a computational study.

This study investigated the adsorption of CO2 molecules on transition metal ions (TM) porphyrins induced carbon nanocone (TM-PICNC) (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) using density functional theory (DFT) to determine the stabilities, energetic, structural, and electronic properties. The results showed that the CO2 molecule is adsorbed on TM-PICNC with adsorption energies ranging from 0.03 to -12.12 kcal/mol. The weak interactions of CO2 gas with Cr, Ni, Cu, and Zn-PICNC were observed, while strong adsorption was found on Sc, Ti, and V-PICNC. The Ti, V, and Cr-PCNC structures were shown to have a suitable energy gap (Eg) for sensing ability because of the effective and physical interaction between these structures and CO2 gas, leading to a short recovery time. DFT calculations also revealed that V-PCNC had a high %ΔEg (about %56.79) and hence high sensitivity to CO2 gas, making it a promising candidate for having good sensing ability to CO2 gas in presence of O2 and H2O gas.

Adsorption of O2 molecule on the transition metals (TM(II) = Sc2+, Ti2+, V2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) porphyrins induced carbon nanocone (TM(II)PCNC).

In this work, the adsorption of the O2 molecule on the transition metals (TM(II) = Sc2+, Ti2+, V2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) porphyrins induced carbon nanocone (TM(II)-PCNC) were investigated using density functional theory (DFT) in terms of stabilities, energetic, structural, and electronic properties. It has been found that the O2 molecule is adsorbed on the TM(II)-PCNC with adsorption energies in the range of 0.29 to -98.32 kcal/mol. The interaction between the O2 gas and the Sc-PCNC molecule from the outer site is the strongest. The interaction of the O2 gas over the Ni-PCNC molecule from both outer and inner sites is the weakest. It can be concluded that the suitable interaction energy (Eg) for sensing ability attributed to the Zn-PCNC because an effective and physical interaction between Zn-PCNC and the O2 gas leads to short recovery time. DFT calculations also clarified that the high %ΔEg of Zn-PCNC and hence the high sensitivity to the O2 gas confirm that the Zn-PCNC molecule is a promising candidate for having a good sensing ability to the O2 gas.

Investigation of the substituted-titanium nanocages using computational chemistry.

We are investigated substitution effects of titanium heteroatoms on band gap, charge and local reactivity of C20-nTin heterofullerenes (n = 1-5), at different levels and basis sets. The C18Ti2-2 nanocage is considered as the most kinetically stable species with the widest band gap of 2.86 eV, in which two carbon atoms are substituted by two Ti atoms in equatorial position, individually. The charges on carbon atoms of C20 are roughly zero, while high positive charge (1.256) on the surface of C19Ti1 prompts this heteofullerene for hydrogen storage. The positive atomic charge on Ti atoms and negative atomic charge on their adjacent C atoms implies that these sites can be influenced more readily by nucleophilic and electrophilic regents, respectively. We examined the usefulness of local reactivity descriptors to predict the reactivity of Ti-C atomic sites on the external surface of the heterofullerenes. The properties determined include Fukui function (F.F.); f (k) and local softness s (k) on the surfaces of the investigated hollow cages. Geometry optimization results reveal that titanium atoms can be comfortably incorporated into the CC network of fullerene. It is most likely associated with the triple-coordination characteristic of titanium atoms, which can well match with the sp2-hybridized carbon bonding structure. According to the values of f (k) and s (k) for the C15Ti5 heterofullerene; the carbon atoms in the cap regions exhibit a different reactivity pattern than those in the equatorial portion of the heterofullerene. The titanium impurity can significantly improve the fullerene's surface reactivity and it allows controlling their surface properties. The band gap of C20-nTin …..(H2)n structures is decreased with increasing n. Hence, C15Ti5 is found as the best hydrogen adsorbent.

Theoretical investigation of the titanium-nitrogen heterofullerenes evolved from the smallest fullerene.

In this survey, we are performed kinetic stability, global reactivity, atomic polar tensor (APT) charge and counter plots of Ti-N heterofullerenes developed from C20 fullerene with the molecular formula of C20-2nTinNn (n = 1-8), at B3PW91/6-311+G∗ level of theory. Also, we are investigated substituent effect of titanium and nitrogen heteroatoms on deuterium adsorption of the heterofullerenes according to density functional theory (DFT). Substituting of Ti-N units with various topology in the cap or equatorial position of heterofullerenes, changes significantly their electronic properties and causes different frontier molecular orbital energy separation (ΔEHOMO-LUMO). Hence, C18Ti1N1 and C10Ti5N5 are found as the best insulated species, while C12Ti4N4 and C4Ti8N8 are considered as the strongest conductive nanocage. Also, C14Ti3N3 cage shows the highest positive APT charge on Ti atom (+1.357, +1.053), while C12Ti4N4 cage shows the lowest positive APT charge on Ti atom (+0.031, -0.292). Accordingly, C14Ti3N3, and C12Ti4N4 exhibit the lowest, and the highest global electrophilicity; ω of 2.58, and 7.01 eV, respectively. As six D2 molecules are approached the C14Ti3N3 heterofullerene, its ΔEHOMO-LUMO (Eg) is increased from 1.29 eV in C14Ti3N3 heterofullerene to 2.11 eV in D2/C14Ti3N3 complex (∼+63.57%) indicating high sensitivity of it to adsorption of six D2 molecules through an exothermic process. As sixteen D2 molecules approaches the C4Ti8N8 nanocage, its Eg reduces from 0.97 to 0.73 eV (∼-24.74%) indicating high electrical conductivity of D2/C4Ti8N8 complex. Therefore, C4Ti8N8 as hopeful sensor, can be generate electrical signals when the D2 molecules approach.