The objective of this project was to develop a new class of molecular photocatalysts for CO2 reduction that will enable breakthrough advances in artificial photosynthesis. A major limitation of existing photocatalytic assemblies is that only a small fraction of absorbed photons are converted into fuel due to inefficiencies in electron transport between the different system components. In the case of molecular catalysts for reduction of CO2, highly reducing electron equivalents are required for catalysis. As a result, the electron flux between the photosensitizer and CO2 reduction catalyst is heavily biased towards the photosensitizer. One method to direct the electron flux towards productive photocatalysis is to design molecular catalysts for CO2 reduction that operate at more favorable potentials than existing catalysts. The conventional approach is to tune the potential of the catalyst through selection of the supporting ligands, however, this only leads to incremental improvements due to the existence of an unfavorable scaling relationship between the rate and potential of catalysis. Our hypothesis is that the catalytic rate and potential can be simultaneously enhanced using bimetallic catalysts in which one metal improves the potential of catalysis and the second metal increases the rate of catalysis. During the course of this project, a few studies reported some success in improving photocatalytic CO2 reduction with heterobimetallic complexes,1-2 demonstrating the potential of this approach to catalyst design.
Revised: December 8, 2020 |
Published: September 28, 2020