Stephania abyssinica leaf extract mediated (Mn, Ni) co-doped ZnO catalyst synthesis for the degradation of organic dye

Abstract

In this work, the (Mn, Ni) co-doped ZnO catalyst was prepared using Stephania abyssinica leaf extract. The prepared sample was assigned with Zn0.98-xMn0.02NixO (x = 0.01, 0.03, 0.05, 0.07, 0.09) and abbreviated as 1NMZO, 3NMZO, 5NMZO, 7NMZO, and 9NMZO, respectively. For comparison purposes, the pure ZnO, Mn-doped ZnO (2 % Mn) (2MZO), and Ni-doped ZnO (5 % Ni) (5NZO) were also prepared with the same procedure mentioned above. The catalysts were characterized by using different instruments. The photocatalytic activities of the catalysts were also evaluated for the degradation of Methylene Blue (MB) dye under visible light. It is showed that pure-ZnO, 2MZO, 5NZO, 1NMZO, 3NMZO, 7NMZO, and 9NMZO catalysts had 33.12, 76.63, 79.73, 84.51, 92.81, 97.34, and 92.30 % degradation efficiency, respectively. However, 5NMZO catalyst showed the highest photocatalytic activity and degrades 99.53 % of MB dye. The higher degradation efficiency of the 5NMZO catalyst could be due to the lower recombination rates of the photo-generated electrons and holes; lower electron transfer resistance; the higher surface area; and higher absorption capacity of the catalyst under visible light. Therefore, (Mn, Ni) co-doped ZnO prepared with Stephania abyssinica leaf extract could be the best candidate for the degradation of organic pollutants.