A reduced graphene oxide (RGO) and carbon black (CB) ink was fabricated with a mixture of ethanol/ethanediol/propanetriol/deionized water as a solvent, and sodium carboxymethyl cellulose (CMC) as a binding and dispersant. The RGO was obtained by reducing graphene oxide using ascorbic acid as a green reductant at a mild temperature of 95 °C. The flexible paper-based electronic circuits were fabricated by inkjet printing the obtained ink on glossy photo paper substrate with an Epson piezoelectric printer. When the loads of RGO, CB, ethanol, ethylene glycol, glycerol, CMC and deionized water were 96 mg, 504 mg, 12 ml, 30 ml, 30 ml, 480 mg and 51 ml, the electrical conductivity, average particle size and viscosity of the ink were 122.4 µs/cm, 1.966 µm and 22.5 mPa s, respectively; and the ink exhibited good acid resistance. A continuous, dense and uniform conductive network was achieved when the printing pass number was 4 for a single circuit. The resistance at both ends of the aforementioned printed circuit (10 × 2 × 0.03338, length × width × thickness, mm) was 0.1 MΩ with a resistivity of 0.661 Ωm for the ink layer, and the circuits showed moderate uniformity, adhesion and mechanical flexibility. In the light-emitting diode operation, the three-dimensional conductive circuits also presented good electrical conductivity.
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This work was financially supported by “A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)” and National Natural Science Foundation of China (Grant No. 31370567).