Conducting polymer supported cerium oxide nanoparticle: Enhanced photocatalytic activity for waste water treatment

Photocatalysts are important milestone for harvesting chemical energy from light energy in the era of massive energy consumption. Cerium oxide nanoparticle, having wide applications from catalysis to biomedical field, has drawback as photocatalyst due to its large band gap. Herein, a conducting polymer, polyaniline has been chosen as an active catalyst support to upgrade photocatalytic activity of cerium oxide nanoparticle. In this work, at first spherical shaped cerium oxide nanoparticle was synthesized by hydrothermal method. Later, polyaniline was decorated on cerium oxide nanoparticle surface via in-situ oxidative polymerization of aniline monomer. The as synthesized polyaniline/cerium oxide nanocomposite exhibits remarkable enhanced photocatalytic efficiency in comparison to cerium oxide nanoparticle or polyaniline in the degradation of a model organic pollutant Rhodamine B in waste water under UV light irradiation. Effects of different pH, Rhodamine B concentration and polyaniline content on photocatalytic activity were also analyzed. The experimental findings demonstrate that nanocomposite with polyaniline and cerium oxide nanoparticle molar ratio 1:1 degrades 91% Rhodamine B in 2 h whereas cerium oxide nanoparticle shows only 10% degradation in same time. The first order rate constant in presence of nanocomposite increases eight fold relative to that in presence of cerium oxide nanoparticle only. The enhanced photocatalytic mechanism is attributed to the synergistic effect between polyaniline and cerium oxide nanoparticle, which reduces recombination rate of photoinduced electron hole pair. Furthermore the nanocomposite is stable upto several cycles of catalysis as evident from their activity study and Field Emission Scanning Electron Microscope images. Thus combination of a conducing polymer with a semiconductor provides an advanced pathway for achieving enhanced photocatalytic activity.