Improving optoelectrical properties of photoactive anatase TiO₂ coating using rGO incorporation during plasma electrolytic oxidation

In this study, photoactive anatase titanium dioxide (TiO₂)/reduced graphene oxide (rGO) composite coatings were successfully developed on titanium substrate using plasma electrolytic oxidation (PEO) process to evaluate the effect of incorporated rGO on their photoactivity and optoelectrical properties. Structural and morphological examinations verified the incorporation of the rGO sheets in the anatase TiO₂ coatings with pancake-like morphology. Optical spectroscopy revealed that a higher content of rGO enhanced the light absorption in UV and visible regions due to the high photo-trapping behavior of the composite samples. Photoluminescence declined by increasing rGO content, which suggested that the recombination of the photogenerated electron-hole pairs was suppressed. As a result, the photocurrent response of the TiO₂/rGO coatings was enhanced significantly under UV radiation compared to the pure one, by which the photoactivity response revealed an over twenty-fold increase for a high concentration of rGO. Moreover, the electron transfer pathways created by the 2D structure of rGO sheets inside the anatase TiO₂ network, promoted the photoresponsivity and photoswitching behavior more than 60%, interestingly.