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Hydrogen-Bond-Network Breakdown Boosts Selective CO2 Photoreduction by Suppressing H2 Evolution.
Die Cong1, Jikai Sun1, Yuwei Pan1
1Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao, 266237, China.
Angewandte Chemie (International Ed. in English)
|March 23, 2024
Summary
Breaking hydrogen bonds in photocatalysts suppresses hydrogen gas evolution, significantly boosting carbon dioxide (CO2) photoreduction efficiency and selectivity. This strategy enhances CO2 conversion rates using poly(ionic liquid)s.
Area of Science:
- Materials Science
- Catalysis
- Photochemistry
Background:
- Conventional carbon dioxide (CO2) photoreduction relies heavily on catalyst and cocatalyst design for efficiency and selectivity.
- Hydrogen (H2) evolution often competes with CO2 reduction, limiting overall performance.
- Poly(ionic liquid)s exhibit strong hydrogen bonding capabilities with solvents, influencing reaction pathways.
Purpose of the Study:
- To investigate the impact of hydrogen bond network breakdown on CO2 photoreduction performance.
- To develop a novel strategy for enhancing CO2 photoreduction by suppressing H2 evolution.
- To explore the use of photosensitive poly(ionic liquid)s as tunable photocatalysts.
Main Methods:
- Design and synthesis of photosensitive poly(ionic liquid)s as photocatalysts.
- Tuning hydrogen bond strength by adjusting solvent composition.
- Utilizing additives like trichloromethane and tetrachloromethane to induce hydrogen bond network breakdown.
- Quantifying H2 evolution and CO production rates and selectivity using gas chromatography and Raman spectroscopy.
- Employing theoretical calculations to confirm the mechanism of hydrogen bond network disruption.
Main Results:
- Hydrogen bond network breakdown effectively suppressed H2 evolution, with rates reduced to zero in the presence of trichloromethane or tetrachloromethane.
- CO production rate increased significantly to 35.4 mmol g⁻¹ h⁻¹ with trichloromethane, a substantial improvement from 0.6 mmol g⁻¹ h⁻¹ without additives.
- CO selectivity reached 98.9% with trichloromethane, compared to 26.2% without additives, demonstrating enhanced CO2 photoreduction performance.
Conclusions:
- Disrupting the hydrogen bond network is a viable strategy to suppress competing H2 evolution in photocatalytic systems.
- Photosensitive poly(ionic liquid)s offer tunable properties for controlling hydrogen bonding and optimizing CO2 photoreduction.
- The developed hydrogen bond network breakdown strategy shows potential for broader application in catalytic reactions involving H2 evolution.
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