A Dual-Function TiO2@CoOx Photocatalytic Fuel Cell for Sustainable Energy Production and Recovery of Metallic Copper from Wastewater

Developing photoelectrochemical systems that couple pollutant removal with resource recovery is of great significance for sustainable wastewater treatment. In this study, a dual-function photocatalytic fuel cell (PFC) was developed using a TiO2 nanotube photoanode modified with an amorphous CoOx cocatalyst, which markedly enhances charge separation and interfacial reaction kinetics. The optimized TiO2@CoOx electrode achieves a twofold enhancement in photocurrent compared to pristine TiO2. When applied to Cu2+-containing wastewater, the PFC achieved 91% Cu2+ removal under N2-purged conditions, with metallic Cu identified as the sole reduction product. Although dissolved oxygen reduced metal recovery efficiency through competitive electron consumption, it simultaneously increased power generation and improved anodic organic degradation. Overall, the results demonstrate that amorphous-CoOx-modified TiO2 photoanodes offer an effective platform for integrating sustainable energy production with wastewater remediation and valuable copper recovery.