▎ 摘　　要

Iron is one of the most abundant metals and an important micronutrient that needs to be consumed in balanced amounts. Excess consumption or deficiency of this micronutrient can have adverse effects on biological functioning of human organs. Hence, the selective detection of this micronutrient is very important. The present work reports a simple and selective sensing of iron (III) in aqueous solutions using potassium doped graphene oxide (Kdoped GO), which is synthesized from Quercus ilex fruits via a greener route of solvo-hydrothermal method. The synthesis of K-doped GO is confirmed with the help of various characterisation techniques viz. X-Ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), and Fourier Transform Infrared Spectroscopy (FT-IR).The Density Functional Theory (DFT) based first principle simulations are carried out to understand the interactions between K-doped GO and iron ions. The simulations reveal desorption of K-ions from the GO sheet due to the extremely high binding energy of iron ions on GO surface, which destabilizes the oxide groups as well as the potassium dopant. The desorbed K-ions from GO surface may react with water to form potassium hydroxide and subsequent quenching of fluorescence. Thus, the synthesized K-doped GO demonstrates its utility as a heavy metal ion sensor with detection limit of 0.345*10-7 M iron ions via spectrofluorometer. Moreover, this material is capable of detecting the presence of iron ions in water up to a limit of 7 ppm with naked eye.