Zwitterionic Conjugated Surfactant Functionalization of Graphene with pH‐Independent Dispersibility: An Efficient Electron Mediator for the Oxygen Evolution Reaction in Acidic Media

Abstract

The functionalization of graphene has been extensively used as an effective route for modulating the surface property of graphene, and enhancing the dispersion stability of graphene in aqueous solutions via functionalization has been widely investigated to expand its use for various applications across a range of fields. Herein, an effective approach is described for enhancing the dispersibility of graphene in aqueous solutions at different pH levels via non‐covalent zwitterion functionalization. The results show that a surfactant with electron‐deficient carbon atoms in its backbone structure and large π–π interactive area enables strong interactions with graphene, and the zwitterionic side terminal groups of the molecule support the dispersibility of graphene in various pH conditions. Experimental and computational studies confirm that perylene diimide amino N‐oxide (PDI–NO) allows efficient functionalization and pH‐independent dispersion of graphene enabled by hydration repulsion effects induced by PDI–NO. The PDI–NO functionalized graphene is successfully used in the oxygen evolution reaction as an electron mediator for boosting the electrocatalytic activity of a Ru‐based polyoxometalate catalyst in an acidic medium. The proposed strategy is expected to bring significant advances in producing highly dispersible graphene in aqueous medium with pH‐independent stability, thus broadening the application range of graphene.

Graphene-Assisted Zwitterionic Conjugated Polycyclic Molecular Interfacial Layer Enables Highly Efficient and Stable Inverted Perovskite Solar Cells

“…26 PDINO@GR was synthesized according to methods reported in a previous study. 27 In brief, the graphite powder was infiltrated by molten potassium metal, and the intercalation of potassium atoms into graphene interlayers spontaneously proceeded due to the ionization potential gap between graphite and potassium. The interlayer distance of graphene was further expanded in a pyridine solvent, which was subsequently functionalized by PDINO.…”

“…Such noncovalently functionalized graphene with PDINO (hereafter denoted PDINO@GR) aptly preserves the intrinsic properties of graphene, compared to oxidized graphene derivatives like graphene oxide or reduced graphene oxide . PDINO@GR was synthesized according to methods reported in a previous study . In brief, the graphite powder was infiltrated by molten potassium metal, and the intercalation of potassium atoms into graphene interlayers spontaneously proceeded due to the ionization potential gap between graphite and potassium.…”

Electrocatalytic acidic oxygen evolution reaction: From nanocrystals to single atoms

“…Graphene functionalized by PDI-NO (Figure 6A) is employed as effective electron mediator in OER to enhance the electrocatalytic activity of Ru-based polyoxometalate catalyst in acidic electrolyte shown in Figure 6B,C. [115] The stability and activity of surfactant-based graphene can be further improved and studied for other Ru-based polyoxometalate materials. A type of inorganic gel has flickered increasing research interest owing to its tunable structure and tremendous electrochemical properties.…”

“…Reproduced with permission: Copyright 2020, Wiley-VCH. [115] (D) Schematic synthesis of DN gels, (E) linear sweep voltammogram curves, (F) and chronoamperometric measurement of DN gels and InFeCo-CCP for 50 h. Reproduced with permission: Copyright 2019, ACS Publication [116] the Pt electrocatalyst. It helps to overcome the CER and allow the OER reaction in acidic seawater.…”

(+)-Catechin-assisted graphene production by sonochemical exfoliation in water. A new redox-active nanomaterial for electromediated sensing

“…To overcome these limitations and the poor usability of graphene-modified surfaces, the generation of redoxactive mediator systems onto graphene nanosheets has been attempted using other strategies. Different chemicals have been used to modify graphene as diaminoanthraquinone [26], zwitterionic surfactants [27], and poly(3,4-ethylenedioxythiophene)/polydopamine complexes [28]; in all cases, graphene functionalization occurs after the synthesis of the material, via long and complex procedures leading to the incorporation of the redox-active compounds. The final result, however, is just an electro-functionalization of the material; to date, not fully reversible catecholic-quinonoid redox system, able to act as an out-and-out mediator, has been reported.…”