Researchers report a new metal-organic framework (MOF) that can selectively target specific types of carbon atoms from the activating CO2 electro-reduction, and it is possible to create elegant products from …
The Game-Changing Catalyst
The metal-organic framework (MOF) catalyst FICN-8, constructed by researchers from the Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences.
This specific MOF catalyst has a 3-D porous structure that allows the reactants access to the catalytic sites — within the metalloporphyrin units. Such design enables systematic variation of electrolyte concentration, an important variable in tuning CO2 reduction selectivity that has mostly been overlooked in prior work.
Upon examination as a heterogeneous electrocatalyst, FICN-8 demonstrated stellar CO2 ER activity and proved the efficacy of this novel catalyst system.
The Electrolyte Enigma
The real advance, though, is learning that the electrolyte’s identity plays a key role in determining what products will be made via CO2 reduction.
FICN-8 showed a CO selectivity as high as 95% in TBAPF6/MeCN electrolyte. However, the major product became formic acid as either water or trifluoroethanol (TFE) were added to be a proton source during hydrolysis.
By incorporating 2.65 mol L−1 water or 0.55 mol L−1 TFE in the electrolyte, the researchers realized an impressive Faradaic efficiency of ~48% for formic acid production.
In addition, this finding underscores the importance of controlling electrolyte composition for CO2 reduction to achieve desired product distribution and new opportunities to tailor selectivity.
Conclusion
We and colleagues have demonstrated a cutting-edge approach to modulate the selectivity of electrochemical CO2 reduction. They show that CO and formic acid, industrial gas related chemical products, can be selectively generated from CO2 by employing the special properties of the FICN-8 MOF catalyst with careful tuning of the electrolyte composition. The findings open a new route to design of catalyst-electrolyte systems for enhanced sustainable CO2 utilization technologies.
