Electrochemical Generation of Nonradical Hydrotrioxide for Sustainable Water Purification.

Sustainable water purification demands oxidation processes that are both highly efficient and chemically self-sufficient. Electrochemical advanced oxidation is inherently green, yet the reactivity of hydroxyl radicals (*OH) is typically confined to the electrode interface, limiting overall treatment efficiency. Here we report the discovery of a putative nonradical hydrotrioxide species, -O3SOOOH, generated in situ by coupling surface-bound *OH with asymmetric peroxides (-O3SOOH) on commercial Pt electrodes. This mediator relays oxidative equivalents from the anode into the bulk solution without reagent consumption, increasing pollutant-degradation rates by 231-856%. Operando spectroscopy, isotope tracing, differential electrochemical mass spectrometry, and density functional theory calculations reveal a pseudo-oxidative, two-electron oxygen-transfer pathway distinct from radical or direct-electron-transfer routes. The putative -O3SOOOH exhibits exceptional product selectivity while maintaining a high oxidative potential. The process proceeds under mild potentials, resists interference from common anions, and can be integrated with reverse-osmosis membranes for continuous, zero-reagent purification. The discovery of hydrotrioxide-mediated oxidation establishes a scalable and low-carbon electrochemical platform for sustainable water treatment.