n- versus p-doping of graphite: what drives its wet-chemical exfoliation?

Abstract

We have performed the syntheses of a novel pyrene-porphyrazine conjugate (ZnPzPy) and a reference porphyrazine (ZnPz) to promote the wet-chemical exfoliation of graphite based on the synergetic use of ultrasonication, centrifugation, and doping. ZnPzPy features, on one hand, a hydrophobic pyrene to anchor onto the basal plane of graphene, and, on the other hand, an amphoteric porphyrazine to either p- or n-dope graphene. To this end, we have characterized individual building blocks, that is, ZnPzPy and exfoliated graphite, and the resulting electron donor-acceptor nanohybrid, that is, ZnPzPy/graphene (ZnPzPy-G), by means of an arsenal of microscopic and spectroscopic techniques. From a full-fledged characterization we conclude that ZnPzPy facilitates the exfoliation of graphite affording suspensions featuring 9.5% of single- or few-layered ZnPzPy-G with a mean average size of 200 ± 140 nm. Importantly, a notable shift of charge density from graphene to ZnPzPy in the ground state of ZnPzPy-G corroborates the preference of exfoliated graphite to undergo p-doping rather than n-doping. As an immediate consequence, a full charge separation leads in the excited state to a 750 ± 150 ps lived charge separated state.

Thioethyl‐Porphyrazine/Nanocarbon Hybrids for Photoinduced Electron Transfer

“…[1][2][3] The acceptor systems are, instead, usually based on carbon nanomaterials. [11] In particular, fullerene derivatives such as [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) have been examples, [64][65][66] the supramolecular interactions between the macrocycle and graphene [74] are mediated by the presence of a pyrene unit linked to the macrocycle through an alkyl chain spacer. These results highlight the fact that nanoassemblies of tetrapyrroles with either CNTs or graphene represent promising materials for the development of novel optoelectronic devices.…”

“…[51,52,[54][55][56] Notably, in the existing literature the pyrene is not directly linked to the macrocycle, but it is, instead, linked through an alkyl chain spacer [52,55] or benzofused to the macrocycle itself. [62] Recently, photoactive hybrid materials composed by porphyrins and phthalocyanines with graphene, [64][65][66][67][68][69][70] and its derivatives (e.g., graphene oxide, [71] and reduced graphene oxide [72,73] ) have also been described. In some of these examples, [64][65][66] the supramolecular interactions between the macrocycle and graphene [74] are mediated by the presence of a pyrene unit linked to the macrocycle through an alkyl chain spacer.…”

“…[62] Recently, photoactive hybrid materials composed by porphyrins and phthalocyanines with graphene, [64][65][66][67][68][69][70] and its derivatives (e.g., graphene oxide, [71] and reduced graphene oxide [72,73] ) have also been described. In some of these examples, [64][65][66] the supramolecular interactions between the macrocycle and graphene [74] are mediated by the presence of a pyrene unit linked to the macrocycle through an alkyl chain spacer. These results highlight the fact that nanoassemblies of tetrapyrroles with either CNTs or graphene represent promising materials for the development of novel optoelectronic devices.…”

Designing Cascades of Electron Transfer Processes in Multicomponent Graphene Conjugates

“…Of great importance is the band‐gap design in graphene materials through chemical functionalization/doping to enable non‐linear optics, [12] photovoltaics, [13] energy‐storage, [14] and biosensing [15] . As of today, numerous examples of non‐covalently functionalized graphene‐based electron donor‐acceptor systems exist, and they are well understood [16–18] . Several chemical methodologies, which are based on well‐established routes, have been developed to modify bulk graphite and, subsequently, to stabilize single and/or few layers of graphene [19–22] .…”

“…[15] As of today,numerous examples of non-covalently functionalized graphene-based electron donor-acceptor systems exist, and they are well understood. [16][17][18] Several chemical methodologies,w hich are based on well-established routes,h ave been developed to modify bulk graphite and, subsequently,tostabilize single and/or few layers of graphene. [19][20][21][22] Cycloadditions,f ree-radical additions,a nd click reactions represent those organic reactions that are most frequently used when sp 2 -carbons of graphene are covalently functionalized.…”