MWCNTs/Ag-ZnO nanocomposite for efficient photocatalytic degradation of congo red

Abstract

Three nanomaterials namely, zinc oxide (ZC), silver-doped zinc oxide (AZ) and multi-walled carbon nanotubes coupled with silver doped zinc oxide nanocomposite (MWAZ) were synthesized, characterized and employed for photo degradation of an organic pollutant, congo red (CR). The photocatalytic activity study showed efficient degradation of CR upon irradiation with UV and visible light in the order of MWAZ > AZ > ZC > Commercial ZnO (ZCO). Percentage photodegradation of 99% and a pseudo 1st order rate constant of 2.3 x 10-2 min-1 were achieved by MWAZ as a catalyst under visible light irradiation, implying photosensitizing ability of MWCNTs and the capability of MWCNTs to hinder recombination of photogenerated holes and electrons. The control experiment in the dark condition gave only 7.9% of degradation efficiency and 5.56 x 10-4 min-1 rate constant, implying the significant role of light source for catalytic degradation of CR.