Simultaneously reducing UO22+ and abating organic pollutants by a self-driven photoelectrocatalytic system with urea modified carbon fibre cathode

Abstract

Organic pollutants in radioactive wastewater severely inhibit uranium reduction by forming stable complexes with uranyl ions (UO₂²⁺), underscoring the urgency of efficient uranium recovery amid nuclear energy expansion. Herein, we develop an innovative self-driven photoelectrocatalytic (PEC) system synergistically recovering uranium and degrading organics. This system features a urea-modified carbon fibre (Urea-CF) cathode for efficient UO₂²⁺ reduction and a hybrid TiO₂ nanorods/silicon solar cell (TNR-SSC) photoanode for rapid pollutant degradation. The Urea-CF cathode, synthesized via hydrothermal urea modification, exhibits an expanded surface area and abundant N-containing functional groups. Under solar illumination, the system simultaneously extracts uranium, degrades organics, and generates electricity without external bias. It demonstrates exceptional versatility across diverse wastewater scenarios, maintaining robust performance under varying reactant concentrations, pH, electrolyte concentrations, and coexisting ions. Remarkably, the system achieves 98.4 % UO₂²⁺ reduction and 98.3 % chlortetracycline (CTC) degradation within 120 min in the solution containing 10 mg L⁻¹ UO₂²⁺ and 20 mg L⁻¹ CTC. The corresponding rate constants are 0.025 min⁻¹ for UO₂²⁺ reduction and 0.032 min⁻¹ for CTC degradation. Additionally, this PEC system maintains >95 % removal efficiency while achieving >80 % recovery of uranium over 50 consecutive cycles. This work presents a sustainable strategy for radioactive wastewater remediation, coupling resource recovery with energy harvesting.