High-yield ball-milling synthesis of extremely concentrated and highly conductive graphene nanoplatelet inks for rapid surface coating of diverse substrates

Highly conductive graphene nanoplatelet (GNP) inks for the rapid surface coating of diverse substrates are prepared by a simple ball-milling method. The method which employs direct yellow 50 (DY50) as a modifier is able to prepare a DY50-decorated GNP nanohybrid (GNP-DY50) from graphite with high production yield (∼100%), high conductivity (up to 3.5 × 104 S/m), high dispersion concentration and excellent film formation ability. The unique structure of DY50, i.e., a rigid, planar and conjugated diazo dye bearing four sulfonate groups, and its strong π-π and charge transfer interactions with exfoliated GNPs, are demonstrated responsible for the efficient synthesis of such GNPs. Very interestingly, the dispersion of 20 mg/mL GNP-DY50 in isopropanol produces a stable and viscous ink, which can achieve the formation of smooth, compact and strongly adhesive GNP coatings within several minutes on the surface of a variety of substrates, e.g., glass beads, copper wires, plastic films, porous sponges and plant leaves. The resulting GNP coatings possess good mechanical property, high conductivity, favorable electrochemical behaviors and efficient electrothermal effects, which have potential applications in a wide range of fields including energy storage devices, electrochemical sensors, smart thin-film heaters and functional coatings.

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