The present study investigated the improvement in photothermal response and temperature enhancement of a commercially available organic thermal oil when small quantities of graphene oxide (0.1 to 0.3% w/v) were added. Characterisation studies revealed the ultrasonic processing procedure did not change the chemical composition of the organic oil, which was found to be thermally stable up to 175 °C before complete decomposition at 315 °C. When the GO-based fluids were exposed to a solar irradiance of 985 Wm-2, the temperature enhancements achieved over the exposure period of 20 minutes typically ranged from 42.4 to 43.2%. The temperature enhancements achieved indicate the GO-based fluids have the potential to be used in direct-absorption solar collectors for improved performance
