In a radical new finding, researchers developed an extraordinary metal-organic framework (MOF) which substantially boosts up the efficiency of CO2 photocatalytic conversion to valuable C2 products, providing hope for both the future energy crisis and carbon neutrality.
Drawing the Power of Distant Orbitals
However, one of the major hurdles in CO2 photoreduction has been the slow multi-electron transfer process and the unreactive C-C coupling steps. But researchers from the Fujian Institute of Research on the Structure of Matter at the Chinese Academy of Sciences and East China University have figured out a way to solve this.
They used a metal-organic framework (MOF) with many delocalized orbitals; which allowed more efficient electron transfer and separation, greatly improving photocatalytic reaction performance. They utilizeda MOF compound – PFC-98, with delocalized orbitals across the metal cluster and the organic linker in order to regulate the building units.
Also, they investigated the isoreticular MOF(PFC-98) that by replacing the 1,4-Di(1H-pyrazol-4-yl)benzene (H2DPB) linker to an electron-deficient linker, 2,5-di(1H-pyrazol-4-yl)thiazolo[5,4-d]thiazole (PyTT), improved significantly in its photocatalytic performance. This strategic change helped to build delocalized orbitals that enabled direct electron excitation transfer from ligand to the metal cluster, making entire process more efficient.
Excellent Catalytic Performance: Promoting C2 Product generation
Already photcatalytic experiments showed very promising results for different bacteriophages. PFC-98 showed excellent acetate (58.14 μmol g−1 h−1 ) and ethanol generation rate (43.14 μmol g−1 h−1 ) of CO2 overall reaction that is ahead in catalytic performance compared with most materials reported so far.
Theoretical calculations and spectroscopy experimentations permitted the exploration of the underlying mechanisms. Due to the molecular structure of ligands and cluster in PFC-98, the lowest unoccupied molecular orbital (LUMO) energy levels of them exhibited proper matching facilitating the delocalized orbitals that are compatible with direct electron excitation transfer. Ultimately, the increase in electron transfer and separation efficiency activated by the formed CQDs caused prolonged excited-state lifetime and enhanced separation of electrons and holes.
In addition, the electron density on the metal cluster in PFC-98 was much higher than that of isoreticular MOF, which facilitated to the production of C2 species in photocatalytic CO2 reaction. The incredibly designed MOFs with the modified from [Cu2(btc)(dmf)2] unit enhances CO2 photoreduction tremendously which shows how strategic MOF design can be to enhance the efficiency of CO 2 reduction.
Conclusion
A significant advancement has been made with the discovery of a metal-organic framework (MOF) containing delocalized orbitals, offering a viable solution to the photocatalytic reduction of CO2 towards C2 species. The researchers have improved the electron transfer and separation efficiency, which may advance a novel and sustainable method for resolving the energy crisis and carbon neutral life. These results not only shed light on a novel design used to tailor the MOF material for CO2 photoreduction, but also open up brand-new opportunities for synthesis and optimization in this field, advancing one step closer towards an environmentally friendly future.
