Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

23 December 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

We report a supramolecular design strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. Specifically, we utilized cobalt tetraphenylporphyrin (Co-TPP), a non-selective oxygen reduction reaction (ORR) catalyst, as a building block to assemble the permanently porous supramolecular cage Co-PB-1(6) bearing six Co-TPP subunits connected through twenty-four imine bonds. Reduction of these imine linkers to amines yields the more flexible porous cage Co-rPB-1(6). Both Co-PB-1(6) and Co-rPB-1(6) cages produce 90-100% H2O2 from electrochemical ORR catalysis in neutral pH water, and we attribute this high selectivity to site isolation of the discrete molecular units, as the analogous Co-TPP monomer generates only a 50% mixture of H2O2 and H2O from electrochemical ORR under the same conditions. The ability to control reaction selectivity in supramolecular structures beyond traditional host-guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications.

Keywords

Oxygen reduction
Porphyrin
Electrochemistry
Hydrogen peroxide
Supramolecular
Porous organic cage

Supplementary materials

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CoBox ORR SI 121619
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TOC
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Supporting Movie 1 PB6
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Supporting Movie 2 rPB6
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