Synthesis of g-C3N4 / ZnO heterostructure photocatalyst for enhanced visible degradation of organic dye

Abstract

The heptazine ring structure and medium bandgap make graphitic carbon nitride (g-C3N4) as a good visible light photocatalyst utilizing solar energy. g-C3N4 was synthesised by utilizing melamine pyrolysis. The g-C3N4 / ZnO nanocomposite prepared by hydrothermal method and resulting product was characterised and investigated photocatalytic decomposition of crystal violet under solar light. The two prominent peaks of pure g-C3N4 in XRD results corresponds to inter-layer structural packing and characteristics interplanar staking peaks of aromatic systems respectively. The calculated interplanar distance of the aromatic unit was 0.326 nm. FESEM images reveals that ZnO formed like a hexagonal rod and g-C3N4 / ZnO formed like a multi layered rod. The magnitude of transition energy calculated using UV DRS spectra was found to be 2.7 eV for g-C3N4 / ZnO nanocomposite and 3.14 eV for ZnO. The nanocomposite showed higher photocatalytic efficiency (97 %) compared to pristine because, the heterojunction present between ZnO and g-C3N4 improves the charge carrier separation of photo generated electron and hole. The scavenging experiment confirms that, photo generated holes play a major role in crystal violet degradation process.