A Dynamically Stabilized Single-Nickel Electrocatalyst for Selective Reduction of Oxygen to Hydrogen Peroxide

TT Wang and ZM Zeng and LY Cao and Z Li and XF Hu and B An and C Wang and WB Lin, CHEMISTRY-A EUROPEAN JOURNAL, 24, 17011-17018 (2018).

DOI: 10.1002/chem.201804312

On-location electrochemical generation of H2O2 is of great current interest. Herein, selective two-electron reduction of O-2 to H2O2 by a single Ni-II(H2O)(6)(2+) cation that is dynamically associated with a negatively charged metal-organic layer (MOL) by hydrogen bonding and coulombic interactions is reported. In contrast, Ni-II centers covalently immobilized on the MOL reduce O-2 to H2O in a four- electron process. Oxygen adsorption by Ni-II(H2O)(6)(2+) followed by two- electron reduction generates neutral Ni-II(H2O)(4)(OH)(OOH)(0), which momentarily disconnects from the negatively charged MOL to avoid the injection of additional electrons. Release of H2O2 from Ni- II(H2O)(4)(OH)(OOH)(0) regenerates Ni-II(H2O)(6)(2+), which regains affinity to the MOL. Such dynamically associated Ni-II single-metal electrocatalysts ensure high selectivity and represent a new strategy for generating selective catalysts for electrochemical production of important chemicals.

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