Water Spillover to Expedite Two‐Electron Oxygen Reduction
Qianyi Li, Zhihao Nie, Wenqiang Wu, Hongxin Guan, Baokai Xia, Qi Huang, Jingjing Duan, Sheng Chen
Abstract
Abstract Limited by the activity‐selectivity trade‐off relationship, the electrochemical activation of small molecules (like O 2 , N 2, and CO 2 ) 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 O 2 to hydrogen peroxide (H 2 O 2 ). 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 H 2 O 2 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 cm 2 , in combination with techno‐economics simulations showing H 2 O 2 production cost strongly dependent on current densities, giving the lowest H 2 O 2 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.