Superhydrophilic and self-cleaning rGO-TiO2 composite coatings for indoor and outdoor photovoltaic applications

The rGO-TiO2 composite catalysts were successfully synthesized by adopting a simple solvothermal method followed by heating at mild condition of 300 degrees C for 1 h, in which graphene oxide (GO) was converted to reduced graphene oxide (rG0). Spin coating technique was used for coating TiO2 and rGO-TiO2 composite catalysts on Indium tin oxide (ITO) coated glass resulting in high transparency of about 75%. The rGO content was varied to optimize the activity of the catalysts. These synthesized catalysts were characterized by various techniques such as X-ray diffraction, Raman, Fourier transformed infrared and UV-vis diffuse reflectance spectral techniques, atomic force microscopy, transmission electron microscopy, scanning transmission electron microscopy and X-ray photoelectron spectroscopy. The anatase phase of TiO2 was successfully achieved with crystallite size of less than 6.7 nm. Incorporation of spherical TiO2 particles on rGO resulted in reduction of band gap from 3.05 to 2.74 eV. The interaction of TiO2 with rGO sheet decreased the rate of electron -hole pair recombination and also facilitated the efficient transfer of electrons from TiO2 to rGO. 0.5 wt% rGO loaded TiO2 composite coatings showed highly efficient superhydrophilicity and self-cleaning property of decontaminating the adsorbed pollutants under simulated solar light irradiation within 30 min. A threefold higher photocurrent was generated by rGO-TiO2 composite catalyst coating than pristine TiO2 coating. This work affords a new pathway for efficient utilization of solar energy by using our synthesized catalysts for indoor as well as outdoor applications.