Improving Molecular Catalyst Activity using Strain-Inducing Carbon Nanotube Supports
Abstract
Support-induced strain engineering is a powerful strategy to modulate the electronic structure of two-dimensional materials. However, controlling strain of planar molecules such as metallophthalocyanines and metalloporphyrins is technically challenging due to their sub–2 nm lateral size. In addition, the effect of strain on molecular properties remains poorly understood. Starting with cobalt phthalocyanine (CoPc), a model CO₂ reduction reaction (CO₂RR) catalyst, we show that carbon nanotubes (CNTs) are ideal substrates for inducing optimum properties through molecular curvature. Using a tandem-flow electrolyzer with monodispersed CoPc on single-walled CNTs (CoPc/SWCNT) as the catalyst, we achieve a methanol partial current density of >90 mA cm⁻² with a selectivity of >60%. CoPc on wide multi-walled CNTs (MWCNTs) leads to only 16.6% selectivity. We report X-ray spectroscopic characterizations to unravel the distinct local coordinations and electronic structures induced by the strong molecule-support interactions. These results agree with our Grand Canonical Density Functional Theory that calculates the energetics as a function of applied potential. We find that SWCNTs induce curvature in CoPc, which improves *CO binding to enable subsequent formation of methanol, while wide MWCNTs favor CO desorption. Thus, we demonstrate that the SWCNT-induced molecular strain increases methanol formation. We also show that induced strain can accelerate the oxygen reduction reaction and CO2RR for other catalysts. Our results show the important role of SWCNTs beyond catalyst dispersion and electron conduction.
Additional Information
The content is available under CC BY 4.0 License. RY acknowledges support from Guangdong Basic and Applied Basic Research Fund (2022A1515011333), Hong Kong Research Grant Council (21300620, 11307120) and State Key Laboratory of Marine Pollution (SKLMP/IRF/0029). CBM and WAG acknowledge support from the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266. The authors declare no competing financial interest.Attached Files
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Additional details
- Eprint ID
- 120406
- Resolver ID
- CaltechAUTHORS:20230324-457152000.11
- 2022A1515011333
- Guangdong Basic and Applied Basic Research Fund
- 21300620
- Research Grants Council of Hong Kong
- 11307120
- Research Grants Council of Hong Kong
- SKLMP/IRF/0029
- State Key Laboratory of Marine Pollution
- DE-SC0021266
- Department of Energy (DOE)
- Created
-
2023-03-30Created from EPrint's datestamp field
- Updated
-
2023-03-30Created from EPrint's last_modified field
- Caltech groups
- Liquid Sunlight Alliance