Guiding graphene derivatization for covalent immobilization of aptamers

Manifesting Epoxide and Hydroxyl Groups in XPS Spectra and Valence Band of Graphene Derivatives

“…However, this peak was absent in the E-xy graphene spectrum, which contained only slightly fewer ketone and carboxyl groups. Furthermore, the elimination of this peak upon the removal of basal-plane groups with a simultaneous rise in the number of carboxyls was indicated earlier [ 47 ]. Given these results, the peak at hv = 289.6 eV was assigned to correspond to the σ* resonance of the hydroxyl groups on the graphene basal plane, fingerprinting this oxygen group in the C K -Edge XAS spectra.…”

“…The nature of the π*-resonance-like maximum with an energy of hv = 289.6 eV exclusively presented in the pre-edge region of the H-xy spectrum was more unambiguous. Some authors assign it to the π* resonance corresponding to carboxyl groups [ 64 ], which is not consistent with a set of studies on the C K -Edge XAS spectra obtained for carboxylated graphenes [ 47 , 53 , 57 ]; others ascribe it to a band of Rydberg states of the C=O group [ 65 ]. However, this peak was absent in the E-xy graphene spectrum, which contained only slightly fewer ketone and carboxyl groups.…”

“…Both spectra were characterized by the presence of a broad hump in the range of v = 3000–3700 cm −1 ,comprising a set of absorption bands of the O–H stretching vibrations in hydroxyl groups, carboxyls, and mainly water molecules [ 46 ]. The high number of the latter was also reflected by the appearance of an intensive narrow absorption band at v = 41,620 cm −1 , attributed to the bending vibrations of the water molecules [ 47 ]. Notably, both absorption bands at v = 1620 cm −1 and v = 3000–3700 cm −1 were of enhanced intensity in the case of H-xy graphene, asserting a higher amount of adsorbed water in this material due to its higher hydrophilicity.…”

Toward On-Chip Multisensor Arrays for Selective Methanol and Ethanol Detection at Room Temperature: Capitalizing the Graphene Carbonylation

“…In ATR-FTIR, spectra absorption bands related to C–O and O–H stretching and bending vibrations in hydroxyl groups, carboxyls, and intercalated water molecules centered at v = 1040–1120, v = 1370, and v = 1620 cm –1 along with the broad hump at v = 3000–3700 cm –1 substantially diminish or disappear (Supporting Information, Section S5), indicating elimination of these oxygen functionalities . At the same time, ketone-related bands centered at v = 1220–1280 and v = 1690–1720 cm –1 along with the band at v = 1580 cm –1 , maturing from the vibrational modes of CC bonds of the graphene network, become prominent . In turn, the narrow intensive π*-resonance being centered at hv = 288.2 eV and attributed to electron transitions from the core levels to π* orbitals of carbonyl and carboxyl groups becomes a dominant one in the C K -edge X-ray absorption spectra after applied carbonylation as seen in Figure a .…”

“…45 At the same time, ketone-related bands centered at v = 1220−1280 and v = 1690−1720 cm −1 along with the band at v = 1580 cm −1 , maturing from the vibrational modes of C�C bonds of the graphene network, become prominent. 46 In turn, the narrow intensive π*-resonance being centered at hv = 288.2 eV and attributed to electron transitions from the core levels to π* orbitals of carbonyl and carboxyl groups becomes a dominant one in the C K-edge X-ray absorption spectra after applied carbonylation as seen in Figure 4a. 44 This resonance is either not presented or hardly distinguishable in the X-ray absorption spectra of the pristine rGO or the initial GO.…”