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Published on: August 7, 2018
Crystal-Facet-Controlled Internal Electric Field in MOF/COF Heterojunction Towards Efficient Photocatalytic Overall
Xiaoyu Chu1, Shikai Liu1, Bing-Bing Luan1
1Heilongjiang Provincial Key Laboratory of CO2 Resource Utilization and Energy Catalytic Materials, School of Material Science and Chemical Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, 150080, P. R. China.
Researchers engineered metal-organic framework (MOF) and covalent organic framework (COF) heterojunctions by controlling crystal facets. This rational design optimized the internal electric field, significantly enhancing photocatalytic water splitting for hydrogen and oxygen production.
Area of Science:
- Materials Science
- Photocatalysis
- Renewable Energy
Background:
- Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are crystalline porous materials with unique structural advantages.
- Integrating MOFs and COFs into heterostructures shows promise for improving photocatalytic hydrogen evolution.
- Controlling the internal electric field in MOF/COF heterojunctions is crucial for enhanced photocatalytic activity but remains challenging.
Purpose of the Study:
- To rationally control the internal electric field in MOF/COF heterojunctions by engineering MOF crystal facets.
- To enhance photocatalytic overall water splitting (OWS) activity through optimized MOF/COF heterostructures.
- To investigate the influence of crystal facets on the performance of MOF/COF photocatalysts.
Main Methods:
- Synthesis of a novel covalently connected MOF/COF photocatalytic system using NH2-MIL-125(Ti) and TpBpy-COF.
- Engineering the crystal facet of MOFs (specifically NH2-MIL-125(Ti)) within the heterojunction.
- Characterization of the MOF/COF heterojunctions to analyze the internal electric field and crystal facet effects.
- Evaluation of photocatalytic overall water splitting (OWS) activity under visible light.
Main Results:
- The exposed crystal facet of MOFs significantly impacts the photocatalytic activity of the MOF/COF system.
- The combination of decahedron NH2-MIL-125(Ti) and TpBpy-COF achieved optimal OWS activity.
- Achieved H2 and O2 evolution rates of 331.6 and 165.7 μmol·g−1·h−1, respectively, under visible light.
- Demonstrated the significant influence of anisotropic facets on the internal electric field at the S-scheme MOF/COF heterojunction interface.
Conclusions:
- Rational control of MOF crystal facets is an effective strategy to tune the internal electric field in MOF/COF heterojunctions.
- The optimized MOF/COF heterojunction exhibits superior photocatalytic overall water splitting performance compared to existing COF-based photocatalysts.
- The study confirms the active crystal facet of NH2-MIL-125(Ti) for water oxidation reactions and highlights the importance of facet engineering in photocatalyst design.
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