Volume 59, Issue 12 pp. 4902-4907
Communication

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

Peter T. Smith

Peter T. Smith

Department of Chemistry, University of California, Berkeley, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720-1460 USA

Search for more papers by this author
Younghoon Kim

Younghoon Kim

Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673 Republic of Korea

Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673 Republic of Korea

Search for more papers by this author
Dr. Bahiru Punja Benke

Dr. Bahiru Punja Benke

Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673 Republic of Korea

Search for more papers by this author
Prof. Kimoon Kim

Corresponding Author

Prof. Kimoon Kim

Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673 Republic of Korea

Center for Self-assembly and Complexity (CSC), Institute for Basic Science (IBS), Pohang, 37673 Republic of Korea

Search for more papers by this author
Prof. Christopher J. Chang

Corresponding Author

Prof. Christopher J. Chang

Department of Chemistry, University of California, Berkeley, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720-1460 USA

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720-1460 USA

Search for more papers by this author
First published: 07 January 2020
Citations: 128

A previous version of this manuscript has been deposited on a preprint server (https://doi.org/10.26434/chemrxiv.11401359.v1).

Graphical Abstract

ORR inspiring: Incorporating cobalt porphyrins into a porous supramolecular cage structure isolates molecular active sites for selective electrochemical oxygen reduction, leading to direct electrosynthesis of hydrogen peroxide in neutral pH water.

Abstract

We report a supramolecular strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. We utilized cobalt tetraphenylporphyrin (Co-TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, 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 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, whereas the Co-TPP monomer gives a 50 % mixture of H2O2 and H2O. Bimolecular pathways have been implicated in facilitating H2O formation, therefore, we attribute this high H2O2 selectivity to site isolation of the discrete molecular units in each supramolecule. 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.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.