Electrochemical treatment coupled with solar light-driven photocatalytic approach: A challenging process in cascade for hydrogen production and wastewater remediation

This study presents an innovative approach for simultaneous hydrogen production and wastewater remediation, integrating electrochemical treatment with solar light-driven photocatalysis. The research focuses on the use of a noble metal-free cathode, based on a electrodeposited composite of Co2P and elemental P, for efficient hydrogen generation from simulated wastewater through water splitting. This composite is characterized, in its optimized form, by an overpotential equal to 133.6 mV (at 10 mA cm-2) and by a Tafel slope of 60.5 mV dec-1. Challenges like the high potential required for the Oxygen Evolution Reaction (OER) and the use of expensive noble metals in electrodes are addressed by employing earth-abundant compounds for electrode fabrication. Additionally, the study explores the degradation of diclofenac (DCF) in wastewater, demonstrating that electrochemical treatment alone is insufficient for organic matter removal. Therefore, a coupled process involving a first electrochemical treatment step followed by a photocatalytic process using BiOCl is proposed. Thanks to the exposure of the (110) active face, BiOCl possesses excellent photocatalytic performances even under solar light irradiation. This hybrid approach not only enhances the efficiency of DCF degradation (about 90%) and reaches an organic matter removal of 59%, but it also improves hydrogen production, offering a sustainable solution for energy generation and water purification in the face of increasing global industrialization and water scarcity.