Biomolecule-assisted exfoliation and dispersion of graphene and other two-dimensional materials: a review of recent progress and applications

摘要

Direct liquid-phase exfoliation of layered materials by means of ultrasound, shear forces or electrochemical\udintercalation holds enormous promise as a convenient, cost-effective approach to the mass\udproduction of two-dimensional (2D) materials, particularly in the form of colloidal suspensions of high\udquality and micrometer- and submicrometer-sized flakes. Of special relevance due to environmental and\udpractical reasons is the production of 2D materials in aqueous medium, which generally requires the use\udof certain additives (surfactants and other types of dispersants) to assist in the exfoliation and colloidal\udstabilization processes. In this context, biomolecules have received, in recent years, increasing attention\udas dispersants for 2D materials, as they provide a number of advantages over more conventional, synthetic\udsurfactants. Here, we review research progress in the use of biomolecules as exfoliating and dispersing\udagents for the production of 2D materials. Although most efforts in this area have focused on graphene,\udsignificant advances have also been reported with transition metal dichalcogenides (MoS2, WS2, etc.) or\udhexagonal boron nitride. Particular emphasis is placed on the specific merits of different types of biomolecules,\udincluding proteins and peptides, nucleotides and nucleic acids (RNA, DNA), polysaccharides,\udplant extracts and bile salts, on their role as efficient colloidal dispersants of 2D materials, as well as on\udthe potential applications that have been explored for such biomolecule-exfoliated materials. These applications\udare wide-ranging and encompass the fields of biomedicine (photothermal and photodynamic\udtherapy, bioimaging, biosensing, etc.), energy storage (Li- and Na-ion batteries), catalysis (e.g., catalyst\udsupports for the oxygen reduction reaction or electrocatalysts for the hydrogen evolution reaction), or\udcomposite materials. As an incipient area of research, a number of knowledge gaps, unresolved issues\udand novel future directions remain to be addressed for biomolecule-exfoliated 2D materials, which will be\uddiscussed in the last part of this review.