MOF-templated fabrication of oxygen-vacancy-rich La-doped CeO2 heterostructure electrodes for boosted capacitive deionization toward efficient phosphate capture

Despite the great potential of capacitive deionization (CDI) in low-cost and eco-friendly phosphate wastewater treatment, the insufficient active sites and sluggish electrochemical kinetics of conventional electrode materials severely limit its dephosphorization performance. Herein, a series of La-doped CeO 2 composites were successfully fabricated via a MOF-derived calcination strategy. Moderate La doping induces abundant surface oxygen vacancies and Ce 3 + active sites while maintaining the original rod-like morphology and cubic fluorite structure of CeO 2 . Benefiting from the optimized defect configuration and porous structure, the optimal La 0.5 CeO 2 electrode achieves rapid electron migration and ion transport, and exhibits a high specific capacitance of 42.53 F/g at 2 A/g. Profiting from the excellent electrochemical characteristics, the La 0.5 CeO 2 electrode delivers excellent CDI dephosphorization performance with a high phosphate electrosorption capacity of 11.5 mg P/g at 1.2 V, a superior charge efficiency of 139.45% and a low energy consumption of 0.19 kWh/kg P, and maintains 99.5% of its initial performance after 20 cycling tests. The excellent phosphate removal capability originates from the synergistic effects of electric-field-driven electrostatic adsorption, oxygen vacancy-mediated ligand exchange and strong Ce/La–O–P chemical coordination. This work provides a feasible strategy for the design and fabrication of high-efficiency rare-earth-based electrodes for CDI water purification.