Optically understanding the dependence of catalysis kinetics on work function of nanocatalyst

In this work, biogenic ZnO and CuO nanoparticles were fabricated by adopting a complete green aqueous approach utilizing Centella asiatica plant extract. The phytochemicals involved in tailoring the nanoscopic metal oxide particles were characterized vividly. Both of the as-synthesized metal oxide particles are spherical and have a narrow size distribution with an average diameter of about 7 nm as measured via HRTEM. Interestingly, X-ray diffraction (XRD) pattern of ZnO nanoparticles displays the exposure of its (100) hexagonal facet. The ensuing ZnO and CuO nanoscale particles briskly enhanced the reduction of methylene blue, which was otherwise very slow. The reaction follows first-order kinetics and the rate constants follow the order k uncat < k ZnO NPs < k CuO NPs. The higher catalytic performance of copper oxide nanoparticles than zinc oxide nanoparticles is succinctly established on the basis of their difference in work function values optically.