Rectangular shaped GO-CuO nanocomposites have gained special attention because of spectacular applications in wastewater treatment. However, due to a lack of research, the fuel additive properties of GO-CuO are still unreported. A proper synthesis and characterisation methods are necessary to investigate the fuel additive properties of GO-CuO. The present research demonstrates the synthesis of graphene oxide (GO) sheets via modified Hummers' method. Further, GO-CuO nanohybrid was prepared by fast, cost-effective, and easy to handle solvothermal approach. The crystal data such as crystal structure, unit cell parameters, space groups, crystal system, and coordinates were explained via XRD analysis. Physical and combustion properties of fuel were analysed at different concentrations (0, 20, 40, 60, and 80 ppm) of diesel-GO-CuO blend for fuel quality parameters. The flash point and fire point of pure diesel oil were observed as 78 and 80 °C which were decreased to 50 and 58 °C, respectively, at 80 ppm concentration. With GO-CuO nanocomposites, the cloud point and pour point decrease until a temperature of −8 °C and − 19 °C, respectively, with a pronounced decrease in the viscosity up to 1.83 mm2/s. Further, the photocatalytic degradation of Methylene Red (MR) dye is studied with the effect of changing H2O2, photocatalyst, and dye concentrations with time. Remarkably, the reaction kinetics and MR degradation of about 94% with sixth-time recyclability were observed. The results of this study showed improved MR degradation when using GO-CuO with H2O2. GO-CuO applications can be utilised to remove other dyes in future and to improve fuel quality parameters.
