Water Spillover to Expedite Two‐Electron Oxygen Reduction

Abstract Limited by the activity‐selectivity trade‐off relationship, the electrochemical activation of small molecules (like O₂, N_2, and CO₂) rapidly diminishes Faradaic efficiencies with elevated current densities (particularly at ampere levels). Nevertheless, some catalysts can circumvent this restriction in a two‐electron oxygen reduction reaction (2e⁻ ORR), a sustainable pathway for activating O₂ to hydrogen peroxide (H₂O₂). Here we report 2e⁻ ORR expedited in a fluorine‐bridged copper metal–organic framework catalyst, arising from the water spillover effect. Through operando spectroscopies, kinetic and theoretical characterizations, it demonstrates that under neutral conditions, water spillover plays a dual role in accelerating water dissociation and stabilizing the key ^*OOH intermediate. Benefiting from water spillover, the catalyst can expedite 2e⁻ ORR in the current density range of 0.1–2.0 A cm⁻² with both high Faradaic efficiencies (99–84.9%) and H₂O₂ yield rates (63.17–1082.26 mg h⁻¹ cm⁻²). Further, the feasibility of the present system has been demonstrated by scaling up to a unit module cell of 25 cm², in combination with techno‐economics simulations showing H₂O₂ production cost strongly dependent on current densities, giving the lowest H₂O₂ price of $0.50 kg⁻¹ at 2.0 A cm⁻². This work is expected to provide an additional dimension to leverage systems independent oftraditional rules.