Two step synthesis of g-C3N4@GO composites with enhanced photoluminescence response

Abstract Tuning the optical properties of graphene oxide (GO) by making composites with 2D materials has attracted considerable interest for various applications. Here, the g-C 3 N 4 @GO composite is synthesised by a two-step modified Hummer’s method with 3 wt% and 7 wt% g-C 3 N 4 . Structural and chemical properties of GO and with g-C 3 N 4 are investigated by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), respectively, while scanning electron microscopy reveals a flake-like structure in g-C 3 N 4 @GO composites. Raman analysis gives an increase in I D /I G ratio from 3.1 to 3.2 due to the formation of defects for 3 wt% g-C 3 N 4 but reduced to 2.9 with 7 wt% g-C 3 N 4 . Optical bandgap of GO (∼3.35 eV) is reduced to ∼3.30 eV (3 wt% g-C 3 N 4 ) and ∼3.25 eV (7 wt% g-C 3 N 4 ) with respective defect edges at ∼2.53 eV, 2.52 eV and 2.50 eV, in good agreement with the photoluminescence (PL) results. The appearance of a broad XRD peak at ∼23.2° signifies the formation of rGO by reducing GO with g-C 3 N 4 , where the existence of HO–C=O in XPS analysis reveals the formation of defects. This is found to be associated with a chemical reaction at the g-C 3 N 4 /GO interfaces and thus makes this system promising with increased PL intensity.