Orbital hybridization mechanism for the enhanced photoluminescence in edge-functionalized sp 2 carbon clusters

Ni Prussian Blue Analogue/Mesoporous Carbon Composite as Electrode Material for Aqueous K‐Ion Energy Storage: Effect of Carbon‐Framework Interaction on Its Electrochemical Behavior

“…al., the mesoporous carbon obtained via self‐assembly from resorcinol‐formaldehyde, with a thermal treatment of 900 °C, exhibited a large aromatic cluster due to the polycyclization; it resulted in the increases in surface area and total pore volume, and explained the high number of sp 2 carbons (see Table S1). In MC‐NiPBA, C1s XPS (Figure B curve b) showed three interesting results: i ) presence of C−N at 285.74 eV due to cyanide linker in [Fe(CN)] n− , ii ) disappearance of π–π* transitions of unsaturated species; this is attributed to a possible disruption of π–π* orbitals of unsaturated carbon by nitrogen groups; due to the fact that cyanide group changes the covalent character of carbon as was observed in Raman results; and iii) the increase in Csp 3 and C−O groups (see Table S1). Based on the results of this work first the ferrocyanide homogenous adsortion take place, this anion can be stabilized due to positive charge on the carbon surface induced by low pH in the solution; then, the addition of Nickel solution reacts with cyanide Nitrogen to produce KNi[Fe(CN) 6 ], due to the material grow with [Fe(CN) 6 ] vacancies, the Ni can coordinate with oxygen species in carbon structure.…”

“…MC material exhibits a triangular shape characteristic for carbon; however, NMC shows a considerably larger charging capacity than that obtained from discharging. Such behavior is different from that reported in the literature, and a likely explanation for that is the large amount of pyrrolic nitrogen present in the carbon structure, , that significantly modifies carbon orbital hybridization . However, in this work the NMC exhibited high amount of pyridinic nitrogen as was discussed in XPS results (see above).…”

Nonradiative Excited‐State Decay via Conical Intersection in Graphene Nanostructures

“…[12][13][14][15] Recent works found that binding chemical groups onto pristine graphene nanostructures can activate the otherwise forbidden transition from the lowest excited singlet state to the ground singlet state (S 1 !S 0 transition) by altering the optical selection rule. [16,18] In addition, the chemical groups on graphene surfaces are found to possibly trap the mobile electron and hole in their vicinity at S 1 state, suggesting that the surface chemical groups may enhance the material's photoluminescent efficiencies by acting as emission centers. [16,18] In addition, the chemical groups on graphene surfaces are found to possibly trap the mobile electron and hole in their vicinity at S 1 state, suggesting that the surface chemical groups may enhance the material's photoluminescent efficiencies by acting as emission centers.…”

“…[13,14,16,17] As a result, the magnitude of oscillator strength of the S 1 !S 0 transition can be enlarged, indicating a larger probability of radiative decays in these chemically modified nanostructures. [16,18] In addition, the chemical groups on graphene surfaces are found to possibly trap the mobile electron and hole in their vicinity at S 1 state, suggesting that the surface chemical groups may enhance the material's photoluminescent efficiencies by acting as emission centers. [17,19,20] In contrast to the role in enhancing the luminescent efficiencies, the role of chemical groups in facilitating the nonradiative excited-state decays has yet understood.…”

Exciton Self-Trapping in sp2 Carbon Nanostructures Induced by Edge Ether Groups

“…Previous experiments have revealed that pristine (unfunctionalized) graphene nanostructures generally exhibit low levels of photoluminescence efficiency, but this efficiency can be largely enhanced via chemical modifications . This phenomenon is presumably due to the fact that the radiative transition in pristine graphene nanostructures is optically forbidden, whereas surface functionalization may alter the optical transition selection rule . As can be seen in Table , binding ether groups on the C54 basal plane activates the otherwise forbidden S1 → S0 transition (nonzero OS).…”