Superior Singlet Oxygen Electrosynthesis Via Neighboring Dual Molecular Oxygen Coactivation for Selective Tetracycline Detoxification.

Oxygen (O2) electroreduction offers a green approach for singlet oxygen (1O2) synthesis in wastewater contaminants detoxification. However, traditional single O2 activation on single-metal catalytic sites seriously suffers from the kinetically-unfavorable desorption of adsorbed superoxide species (center dot O2-*/center dot OOH*). Here, we demonstrate a novel dual O2 coactivation pathway on shortened Fe1-OV-Ti sites for superior 1O2 electrosynthesis through a rapid disproportionate process between surface-confined center dot O2-*/center dot OOH*. Theoretical calculations combined with in situ electrochemical spectroscopies demonstrated that the shortened distance between Fe single atom and adjacent unsaturated Ti atom facilitates the direct recombination of surface-confined Fe-center dot OOH and Ti-center dot OO- to yield 1O2, bypassing the formidable center dot O2-*/center dot OOH* desorption process. Impressively, Fe1-OV-Ti could realize an excellent 1O2 electrosynthesis rate of 54.5 mu mol L-1 min-1 with an outstanding 1O2 selectivity of 97.6 % under neutral condition, surpassing that of Fe1-O-Ti (27.1 mu mol L-1 min-1, 91.7 %). Using tetracycline (TC) as a model pollutant, the resulting Fe1-OV-Ti electrode achieved nearly 100 % degradation in 120 min at -0.6 V, meanwhile preventing the generation of toxic intermediates. This study provides a new 1O2 electrosynthesis strategy by controlling the distance of adjacent catalytic sites for the coactivation of dual molecular oxygen. By manipulating the atomic distance between Fe single atom and adjacent unsaturated Ti atom, a novel dual O2 coactivation pathway is designed for superior singlet oxygen electrosynthesis through a rapid disproportionate process between surface-confined center dot O2-*/center dot OOH*, offering an efficient oxygen activation strategy for antibiotics detoxicification. image