Pulsed Electrolysis Unlocks Non-Noble-Metal Catalysis for Per- and Polyfluoroalkyl Substance Defluorination in Water.

Abstract

Per- and polyfluoroalkyl substances (PFAS) pose severe threats to human health and global sustainable development. Electrochemical reduction (ECR) provides a promising reagent-free strategy for PFAS defluorination, yet its practical deployment is severely limited by cathodic PFAS repulsion and C-F bond stability. Herein, we report a pulsed electrolysis strategy using a non-noble metal Co/Ni electrode for PFAS defluorination in water. While Co sites activated C-F bonds and acted as atomic hydrogen (H*) pumps, Ni incorporation upshifted the d-band center of Co sites and strengthened PFAS/H* adsorption, collectively driving electron injection into C-F antibonding orbitals and subsequent H/F substitution. Furthermore, pulsed potentials dynamically modulated interfacial electrostatic interactions, enriching PFAS/protons on the electrode surface for effective defluorination. This strategy achieved a 10.5-fold higher perfluorooctanoic acid (PFOA, 0.5 μM) removal rate than that of potentiostatic operation, outperformed noble metal-based counterparts, delivered 83.8% PFOA removal and 87.3% defluorination within 5 h, and retained robust stability over 100 h. Moreover, it achieved up to 96.9% removal of multiple PFAS in real wastewater and reduced energy consumption by over 56% in continuous-flow electrolysis compared with reported technologies. Overall, this work provides a low-cost and sustainable non-noble metal electrochemical platform for practical PFAS treatment.