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Yalcin K, Kurtoğlu-Öztulum SF, Sarac Oztuna FE, Kanat GH, Unal U, Uzun A. Active Sites and Their Individual Turnover Frequencies for Ethylene Hydrogenation on Reduced Graphene Aerogel. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:4044-4053. [PMID: 38369776 DOI: 10.1021/acs.langmuir.3c02848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Graphene aerogel (GA) was reduced at various temperatures to prepare a series of reduced graphene aerogels (rGAs) with different surface characteristics. Detailed characterization demonstrated that an increase in the thermal reduction temperature leads to an increase in surface area accompanied by an increase in surface density of defect sites formed by the removal of the oxygen-containing functional groups. rGA samples were then tested for ethylene hydrogenation under identical conditions. A comparison of catalytic performances of each catalyst demonstrated that the rGA sample prepared by reduction in Ar at 900 °C (rGA-900) provides the highest performance compared with others prepared at lower temperatures. Next, we analyzed the per-gram activity of each catalyst as a sum of individual contributions from different defect sites quantified by Raman spectroscopy and CHNS-O analysis to determine the individual turnover frequencies (TOFs) of each active site. This analysis identified polyene-like structures and interstitial defects associated with amorphous sp2 bonded carbon atoms as the dominant active sites responsible for hydrogenation. A comparison of their TOFs further indicated that the polyene-like structures provide approximately ten times higher TOF compared to those associated with the amorphous carbon defects. These results, identifying the dominant active centers and quantifying their corresponding TOFs, provide opportunities toward the rational design of GA-based carbocatalysts.
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Affiliation(s)
- Kaan Yalcin
- Department of Chemical and Biological Engineering, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Koç University TÜPRAŞ Energy Center (KUTEM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - Samira F Kurtoğlu-Öztulum
- Department of Chemical and Biological Engineering, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Koç University TÜPRAŞ Energy Center (KUTEM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Department of Materials Science and Technology, Faculty of Science, Turkish-German University, Sahinkaya Cad. 86, Beykoz, 34820 Istanbul, Turkey
| | - F Eylul Sarac Oztuna
- Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - Gizem Hasibe Kanat
- Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - Ugur Unal
- Koç University TÜPRAŞ Energy Center (KUTEM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Koç University Surface Science and Technology Center (KUYTAM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - Alper Uzun
- Department of Chemical and Biological Engineering, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Koç University TÜPRAŞ Energy Center (KUTEM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
- Koç University Surface Science and Technology Center (KUYTAM), Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
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Kurtoğlu-Öztulum SF, Yalçın K, Hoffman AS, Jalal A, Zhao Y, Gates BC, Bare SR, Unal U, Uzun A. Ionic Liquid Sheath Stabilizes Atomically Dispersed Reduced Graphene Aerogel‐Supported Iridium Complexes during Ethylene Hydrogenation Catalysis. ChemCatChem 2022. [DOI: 10.1002/cctc.202200553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - Kaan Yalçın
- Koç University: Koc Universitesi Chemical and Biological Engineering TURKEY
| | | | - Ahsan Jalal
- Koç University: Koc Universitesi Chemical and Biological Engineering TURKEY
| | - Yuxin Zhao
- Koç University: Koc Universitesi Chemical and Biological Engineering TURKEY
| | - Bruce C. Gates
- UC Davis: University of California Davis Chemical Engineering TURKEY
| | - Simon R. Bare
- SLAC: Stanford Linear Accelerator Center SSRL TURKEY
| | - Ugur Unal
- Koç University: Koc Universitesi Chemistry TURKEY
| | - Alper Uzun
- Koç University: Koc Universitesi Chemical and Biological Engineering Koc UniversityDepartment of Chemical and Biological EngineeringRumelifeneri YoluSariyer 34450 Istanbul TURKEY
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