Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites
Using a combination of experimental and computational investigations, we assemble a consistent mechanistic model for the oxygen reduction reaction (ORR) at molecularly well-defined graphite-conjugated catalyst (GCC) active sites featuring aryl-pyridinium moieties (N⁺-GCC). ORR catalysis at glassy ca...
| Main Authors: | , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Chemical Society (ACS)
2018
|
| Online Access: | http://hdl.handle.net/1721.1/118382 https://orcid.org/0000-0002-5338-8876 https://orcid.org/0000-0002-6164-485X https://orcid.org/0000-0001-8659-6535 https://orcid.org/0000-0002-6556-3571 https://orcid.org/0000-0001-7111-0176 https://orcid.org/0000-0003-1016-3420 |
| _version_ | 1826188659435503616 |
|---|---|
| author | Ricke, Nathan Darrell Murray, Alexander T Shepherd, James J Welborn, Matthew Gregory Fukushima, Tomohiro Van Voorhis, Troy Surendranath, Yogesh |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Ricke, Nathan Darrell Murray, Alexander T Shepherd, James J Welborn, Matthew Gregory Fukushima, Tomohiro Van Voorhis, Troy Surendranath, Yogesh |
| author_sort | Ricke, Nathan Darrell |
| collection | MIT |
| description | Using a combination of experimental and computational investigations, we assemble a consistent mechanistic model for the oxygen reduction reaction (ORR) at molecularly well-defined graphite-conjugated catalyst (GCC) active sites featuring aryl-pyridinium moieties (N⁺-GCC). ORR catalysis at glassy carbon surfaces modified with N⁺-GCC fragments displays near-first-order dependence in O₂ partial pressure and near-zero-order dependence on electrolyte pH. Tafel analysis suggests an equilibrium one-electron transfer process followed by a rate-limiting chemical step at modest overpotentials that transitions to a rate-limiting electron transfer sequence at higher overpotentials. Finite-cluster computational modeling of the N⁺-GCC active site reveals preferential O₂ adsorption at electrophilic carbons alpha to the pyridinium moiety. Together, the experimental and computational data indicate that ORR proceeds via a proton-decoupled O₂ activation sequence involving either concerted or stepwise electron transfer and adsorption of O₂, which is then followed by a series of electron/proton transfer steps to generate water and turn over the catalytic cycle. The proposed mechanistic model serves as a roadmap for the bottom-up synthesis of highly active N-doped carbon ORR catalysts. Keywords: density functional theory; electrocatalysis; mechanistic studies; N-doped carbon; oxygen reduction |
| first_indexed | 2024-09-23T08:02:44Z |
| format | Article |
| id | mit-1721.1/118382 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:02:44Z |
| publishDate | 2018 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/1183822022-09-23T10:32:24Z Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites Ricke, Nathan Darrell Murray, Alexander T Shepherd, James J Welborn, Matthew Gregory Fukushima, Tomohiro Van Voorhis, Troy Surendranath, Yogesh Massachusetts Institute of Technology. Department of Chemistry Surendranath, Yogesh Ricke, Nathan Darrell Murray, Alexander T Shepherd, James J Welborn, Matthew Gregory Fukushima, Tomohiro Van Voorhis, Troy Surendranath, Yogesh Using a combination of experimental and computational investigations, we assemble a consistent mechanistic model for the oxygen reduction reaction (ORR) at molecularly well-defined graphite-conjugated catalyst (GCC) active sites featuring aryl-pyridinium moieties (N⁺-GCC). ORR catalysis at glassy carbon surfaces modified with N⁺-GCC fragments displays near-first-order dependence in O₂ partial pressure and near-zero-order dependence on electrolyte pH. Tafel analysis suggests an equilibrium one-electron transfer process followed by a rate-limiting chemical step at modest overpotentials that transitions to a rate-limiting electron transfer sequence at higher overpotentials. Finite-cluster computational modeling of the N⁺-GCC active site reveals preferential O₂ adsorption at electrophilic carbons alpha to the pyridinium moiety. Together, the experimental and computational data indicate that ORR proceeds via a proton-decoupled O₂ activation sequence involving either concerted or stepwise electron transfer and adsorption of O₂, which is then followed by a series of electron/proton transfer steps to generate water and turn over the catalytic cycle. The proposed mechanistic model serves as a roadmap for the bottom-up synthesis of highly active N-doped carbon ORR catalysts. Keywords: density functional theory; electrocatalysis; mechanistic studies; N-doped carbon; oxygen reduction United States. Department of Energy. Office of Basic Energy Sciences (Award DE-SC0014176) 2018-10-09T13:58:06Z 2018-10-09T13:58:06Z 2017-09 2017-09 Article http://purl.org/eprint/type/JournalArticle 2155-5435 2155-5435 http://hdl.handle.net/1721.1/118382 Ricke, Nathan D. et al. “Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites.” ACS Catalysis 7, 11 (October 2017): 7680–7687 © 2017 American Chemical Society https://orcid.org/0000-0002-5338-8876 https://orcid.org/0000-0002-6164-485X https://orcid.org/0000-0001-8659-6535 https://orcid.org/0000-0002-6556-3571 https://orcid.org/0000-0001-7111-0176 https://orcid.org/0000-0003-1016-3420 en_US http://dx.doi.org/10.1021/acscatal.7b03086 ACS Catalysis Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) Prof. Surendranath via Erja Kajosalo |
| spellingShingle | Ricke, Nathan Darrell Murray, Alexander T Shepherd, James J Welborn, Matthew Gregory Fukushima, Tomohiro Van Voorhis, Troy Surendranath, Yogesh Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title | Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title_full | Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title_fullStr | Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title_full_unstemmed | Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title_short | Molecular-Level Insights into Oxygen Reduction Catalysis by Graphite-Conjugated Active Sites |
| title_sort | molecular level insights into oxygen reduction catalysis by graphite conjugated active sites |
| url | http://hdl.handle.net/1721.1/118382 https://orcid.org/0000-0002-5338-8876 https://orcid.org/0000-0002-6164-485X https://orcid.org/0000-0001-8659-6535 https://orcid.org/0000-0002-6556-3571 https://orcid.org/0000-0001-7111-0176 https://orcid.org/0000-0003-1016-3420 |
| work_keys_str_mv | AT rickenathandarrell molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT murrayalexandert molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT shepherdjamesj molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT welbornmatthewgregory molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT fukushimatomohiro molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT vanvoorhistroy molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites AT surendranathyogesh molecularlevelinsightsintooxygenreductioncatalysisbygraphiteconjugatedactivesites |