Degradation of organics with simultaneous recovery of silver in a simple visible-light responsive dual photoelectrode photocatalytic fuel cell

Abstract

An efficient photocatalytic fuel cell (PFC) system driven by visible-light using a BiVO₄ photoanode and a Cu₂O/CuO photocathode has been designed for phenol degradation with simultaneous silver recovery. Using this system, 86.4% removal of phenol (5 mg L⁻¹) and 100% recovery of Ag (40 mg L⁻¹) were achieved within 4 h, which was more efficient than the individual PFC system without Ag⁺ ions. High Ag⁺ concentration and low initial pH were beneficial for phenol removal. The surface variations of the photoanode and photocathode were characterized by the FE-SEM, XRD and XPS techniques. The Ag species recovered on the photoanode was found to be metallic Ag and Ag₂O and the Ag species recovered on the photocathode was determined to be metallic Ag. The Ag₂O–BiVO₄ heterojunction inhibited the recombination of photo-generated electron–hole pairs. Active radicals including h⁺, ˙O₂⁻ and ˙OH were determined to be responsible for the degradation of organics by quenching experiments and ESR analysis. The proposed system provided an economical and efficient way for the oxidation of organic contaminants and metal ion recovery.