Facile synthesis of cation doped ZnO-ZnCo2O4 hetero-nanocomposites for photocatalytic decomposition of aqueous organics under visible light

Heterostructured cation doped ZnO-ZnCo2O4 nanocomposites having different cobalt loading were synthesized in a facile co-precipitation method followed by calcination at an optimum temperature. The structural features of the nanocomposites were confirmed using various characterization techniques. The morphologies of the heterostructured nanocomposites were changed from mixed structure (flakes and nano-rod) to spherical shape (cation doped ZnO-ZnCo2O4 to ZnCo2O4) when the cobalt composition varied from 10% to 50% of cobalt. The catalyst with 20% cobalt content exhibited the highest visible light photocatalytic performance towards degradation of Methyl Orange dye (MO dye) (92% degradation) and 2-chiorophenol (2-CP) (similar to 100% degradation). The rate-constant values for MO dye, and 2-CP degradations were 0.0177 min(-1) and 0.0263 min(-1) respectively, which are significantly higher than recent published materials, revealed by a comparison study. The enhanced photocatalytic activity is due to the heterojunction interfaces, which help to separate and transfer electron-hole pair as evidenced from PL spectra. Active species trapping experiments revealed that photogenerated hydroxyl radical played key role in degradation reaction. Moreover, the degradation products of MO dye and 2-CP were analyzed using mass spectroscopy, and their probable degradation pathways were arrived accordingly. (C) 2017 Elsevier B.V. All rights reserved.