Z-scheme MoO3 anchored-hexagonal rod like ZnO/Zn photoanode for effective wastewater treatment, copper reduction accompanied with electricity production in sunlight-powered photocatalytic fuel cell
By Lam, Sze-Mun; Sin, Jin-Chung; Zeng, Honghu; Lin, Hua; Li, Haixiang; Qin, Zuzeng; Lim, Jun Wei; Mohamed, Abdul Rahman
Published in Separation and Purification Technology
2021
Abstract
This study presents a sunlight-powered photocatalytic fuel cell (PFC) which can directly produce electricity with synchronized oxidative degradation of organics and reductive treatment of copper ion (Cu2+). MoO3/ZnO/Zn fabricated by facile wet-chemical and impregnation procedures is used as a photoanode in a dual-chamber system. The optimized PFC with a maximum power density of 0.007 mW cm−2, an open circuit voltage of 835 mV and a short circuit current density of 0.082 mA cm−2 can be achieved at 200 mg L−1 initial Cu2+ concentration at solution pH 3. Under these conditions, more electron-hole pairs were separated on the photoanode for phenol oxidation, and the electrons were transferred to the cathode for Cu2+ reduction. About 89.5% chemical oxygen demand (COD) of 40 mg L−1 initial phenol concentration was removed, while 93.5% removal efficiency for 200 mg L−1 initial Cu2+ concentration can be reached within 240 min. The ameliorated photoelectrochemical performance could be owing to the Z-scheme MoO3/ZnO heterojunction that can extend optical absorption and facilitated charge separation according to the optical and electronic analyses. The stable cyclic operation of this PFC was achieved. For the real plating wastewater treatment, the COD removal of phenol, Cu2+ reduction and maximum power density output were 73.6%, 85.0% and 0.005 mW cm−2, respectively.