Solar-Driven Thermally and Electrically Operated Au/TiO ₂ NTs/Ti Chemical System for Oilfield Wastewater to Hydrogen Generation and Collaborative Organics Purification

Effective treatment of oilfield wastewater poses a significant issue for sustainable oilfield operations. The organically rich nature of oilfield wastewater complicates conventional treatment but offers a unique opportunity for electrochemical resource recovery. Herein, this study develops a solar-driven electrochemical system that simultaneously purifies oilfield wastewater and generates hydrogen using a robust Au/TiO2 nanotube array (Au/TiO2 NTs/Ti) anode. By integrating solar-electro and solar-thermo energy, the system utilizes organic pollutants in wastewater (e.g., polyacrylamide and surfactants) as sacrificial agents to replace the energy-intensive oxygen evolution reaction. The Au/TiO2 NTs/Ti electrode demonstrates excellent thermal stability and oxidation resistance comparable to Pt anode, achieving a hydrogen evolution Coulombic efficiency of 92% alongside a chemical oxygen demand removal efficiency greater than 80% under optimized conditions (50 mA, 90 °C). Furthermore, the hybrid solar chemical system maintains high solar energy utilization and long-term stability across diverse wastewater types including water flooding, polymer flooding, and alkaline surfactant polymer (ASP) flooding effluents. This work establishes a fundamental “waste-to-value” paradigm, confirming that robust electrode design can effectively transform industrial wastewater burdens into valuable hydrogen energy resources.