Conventional catalysts and energy-storage materials rely on static architectures that are typically comprised of immobilized active sites. While effective for simple chemical transformations and chemical storage, this material paradigm lacks the flexibility to accommodate dynamic feed streams, execute complex chemical reactions, or absorb and desorb chemicals near standard temperature and pressure. Covalent organic frameworks (COFs) have potential to alter the conventional catalyst and energy-storage paradigm for powerful control over transport and reactivity. COFs are comprised of organically linked, periodic molecular structures and are ideally suited for tuning porosity and embedded active sites. Scientists at NREL have developed photo-responsive COFs whose pore diameters can be adjusted by exposure to light to gate dynamic catalytic and chemical-storage domains within the framework, offering unprecedented control over interfacial transport and catalytic activity.
Nature has mastered the gated control of chemical transport across the interface of cellular membranes. This mastery allows biological systems to adapt to changing environmental conditions and substrate concentrations. Once inside the membrane, staged enzymatic networks provide cascade control over complex chemical transformations necessary for cellular metabolism. However, the human-made ability to synthesize systems that display the same degree of control over transport and chemical reactivity has yet to be realized for conventional catalyst and chemical-storage materials. Scientists at NREL have developed photo-controllable covalent organic frameworks (COFs) with the potential to alter the conventional catalyst and energy-storage paradigm.
NREL’s COFs are comprised of organically linked, periodic molecular structures incorporating azobenzene functional groups, which undergo cis,trans-isomerization upon exposure to ultraviolet light, to control the size of the pores within the COF and gate the passage of chemicals through the pores. Using these photo-controllable COFs, scientists at NREL have developed (1) gated COFs for hydrogen storage and light-activated hydrogen release, (2) COFs in colloidal systems, (3) catalytic reactions using COFs, and (4) photo-enhanced formic acid decomposition using COFs.
To learn more about NREL’s Gated Covalent Organic Frameworks for Catalysis and Energy Storage, please contact Eric Payne at:
Applications and Industries
- Electrochemical storage and retrieval of renewable energy for the grid
- Fuel cells for vehicles
- Reduction of carbon dioxide for hydrocarbons
- Cascade redox reactions
NREL’s photo-controllable covalent organic frameworks can enable
- Cascade catalysis reactions with unprecedented complexity and efficiency and
- Efficient and accessible chemical storage via absorption and desorption.