Photoelectrochemical CO₂ Reduction to CO Enabled by a Molecular Catalyst Attached to High-Surface-Area Porous Silicon
A high-surface-area p-type porous Si photocathode containing a covalently immobilized molecular Re catalyst is highly selective for the photoelectrochemical conversion of CO₂ to CO. It gives Faradaic efficiencies of up to 90% for CO at potentials of −1.7 V (versus ferrocenium/ferrocene) under 1 sun illumination in an acetonitrile solution containing phenol. The photovoltage is approximately 300 mV based on comparisons with similar n-type porous Si cathodes in the dark. Using an estimate of the equilibrium potential for CO₂ reduction to CO under optimized reaction conditions, photoelectrolysis was performed at a small overpotential, and the onset of electrocatalysis in cyclic voltammograms occurred at a modest underpotential. The porous Si photoelectrode is more stable and selective for CO production than the photoelectrode generated by attaching the same Re catalyst to a planar Si wafer. Further, facile characterization of the porous Si-based photoelectrodes using transmission mode FTIR spectroscopy leads to highly reproducible catalytic performance.
Jia, X.; Stewart-Jones, E.; Alvarez-Hernandez, J. L.; Bein, G. P.; Dempsey, J. L.; Donley, C. L.; Hazari, N.; Houck, M. N.; Li, M.; Mayer, J. M.; Nedzbala, H. S.; Powers, R. Photoelectrochemical CO₂ Reduction to CO Enabled by a Molecular Catalyst Attached to High Surface Area Porous Silicon. J. Am. Chem. Soc., 2024, 146 (12), 7998-8004. https://doi.org/10.1021/jacs.3c10837
