Synthesis and characterization of nanocrystalline N-doped semiconductor metal oxide and its visible photocatalytic activity in the degradation of an organic dye

Abstract

N-doped Zinc Oxide (N-ZnO) was synthesized by a sol-gel cum combustion method and it was characterized by various techniques such as FT-IR, XRD, UV-DRS, FESEM, HRTEM, AFM, BET isotherm and Raman spectroscopy. The prepared material was found to possess a band gap energy of 3.1eV. Surface characterization techniques showed the material to possess a high surface area and surface roughness which would play a role in enhancing its photocatalytic efficiency. The photocatalytic activity of the prepared catalyst was evaluated by the degradation of a model organic dye – Eosin Yellow under visible light irradiation. Preliminary experiments showed the catalyst to be efficient across all pH values. A catalyst dosage of 0.7g/L gave better results and high degradation efficiency was observed for up to 5mg/L dye concentration. Kinetic studies were carried out for different initial dye concentrations from 5mg/L to 50mg/L. Results showed the photodegradation reaction to follow pseudo first order kinetics. The progress of the reaction was monitored by UV–vis absorption studies and reduction in Chemical Oxygen Demand of the solution. The presence of electrolytes did not diminish the photodegradation efficiency of the catalyst. Reusability studies showed the material to retain its original activity even after the 3rd cycle of use.