Janus electrocatalytic flow-through membrane enables highly selective singlet oxygen production

The importance of singlet oxygen ((1)O(2)) in the environmental and biomedical fields has motivated research for effective (1)O(2) production. Electrocatalytic processes hold great potential for highly-automated and scalable (1)O(2) synthesis, but they are energy- and chemical-intensive. Herein, we present a Janus electrocatalytic membrane realizing ultra-efficient (1)O(2) production (6.9 mmol per m(3) of permeate) and very low energy consumption (13.3 Wh per m(3) of permeate) via a fast, flow-through electro-filtration process without the addition of chemical precursors. We confirm that a superoxide-mediated chain reaction, initiated by electrocatalytic oxygen reduction on the cathodic membrane side and subsequently terminated by H(2)O(2) oxidation on the anodic membrane side, is crucial for (1)O(2) generation. We further demonstrate that the high (1)O(2) production efficiency is mainly attributable to the enhanced mass and charge transfer imparted by nano- and micro-confinement effects within the porous membrane structure. Our findings highlight a new electro-filtration strategy and an innovative reactive membrane design for synthesizing (1)O(2) for a broad range of potential applications including environmental remediation.