Preparation, characterization and enhanced photocatalytic activities of zinc oxide nano rods/silicon carbide composite under UV and visible light irradiations

Abstract

ZnO/SiC nanocomposites were fabricated by a simple sol-gel process for exhibiting an enhanced photocatalytic activity under UV and visible light irradiation. The prepared photocatalysts were characterized by XRD, UV-DRS, FT-IR, AFM, FE-SEM, EDAX, HR-TEM, SAED, XPS and EPR analysis. XRD and FE-SEM showed that the prepared photocatalysts were nanocrystalline. Band gap energies of synthesized ZnO/SiC composites were calculated using diffuse reflectance spectroscopy (DRS). High surface roughness and porosity were confirmed by AFM analysis.The XPS survey spectrum clearly revealed the presence of Zn (2p), Si (2p), O1s (530.2eV)and C (1s) in the prepared composite material. ZnO/SiC photocatalyst produced OH radicals instantaneously within 60s and 15min for UV and visible irradiation respectively when compared to 180s and 30min for pristine ZnO which were confirmed by EPR spin trapping technique. This fast rate of OH radical formation is due to the presence of charge transfer mechanism in the prepared ZnO/SiC photocatalyst. The photocatalytic efficacy of the prepared catalyst was studied for the degradation of phenol as a model pollutant in the aqueous phase. The photodegraded samples were analyzed by UV–visible spectroscopy, COD analysis. ZnO/SiC nanocomposites showed a two fold increase in photocatalytic activity compared to pristine ZnO and reusability without affecting its performance upto three cycles. It also followed a pseudo first order kinetics.