A self-driven solar coupling system with TiO₂@MXene cathode for effectively eliminating uranium and organics from...

The inevitable organic matters in radioactive wastewater and contaminated waters pose great challenge in uranium recycling by traditional techniques. Here, a self-driven solar coupling system (SSCS), which was assembled by a TiO₂ @MXene/CF cathode and a monolithic photoanode, was proposed for synergistically recycling uranium and degrading organics from complex radioactive wastewater, combining with electricity production. The TiO₂ @MXene/CF was prepared via a simple annealing process with in-situ derived TiO₂ nanoparticles decorated Ti₃C₂ MXene coated on carbon felt (CF). Under sunlight illumination, the photoanode captured electrons of organics, and drove electrons to the TiO₂ @MXene/CF, which exhibited an exceptional UO₂²⁺ adsorption and reduction capacity because TiO₂ nanoparticles provided plenty of surface hydroxyl groups for UO₂²⁺ adsorption, and the unique two-dimensional MXene facilitated the charge transfer. The SSCS with TiO₂ @MXene/CF removed almost 100% UO₂²⁺ and organics with rate constants of ∼21 and ∼6.9 times those of the system with CF, accompanying with excellent power output (∼1000 μW·cm^-2). The fixed uranium on TiO₂ @MXene/CF was effectively reduced into insoluble UO₂ (91.1%), and no obvious decay was observed after 15 repeated uses. This study proposes a multi-functional and easy-operated way for remediating radioactive wastewater and contaminated waters, and gives valuable insights in designing cathode materials for uranium reduction.