Photoelectrocatalytic reduction of CO₂ to formate using immobilized molecular manganese catalysts on oxidized porous silicon
The reduction of carbon dioxide (CO₂) to formate using molecular catalysts immobilized on high surface area porous silicon is described. Manganese complexes of the type (ᴿbpy)Mn(CO)₃Br (bpy = 2,2′-bipyridine) were prepared with silatrane groups on the bpy ligand for attachment to oxide-coated porous silicon (SiOₓ-porSi). SiOₓ-porSi wafers were formed by heating hydrogen-terminated p-type porous silicon wafers under air, and the manganese complexes were immobilized on SiOₓ-porSi by heating at 80 °C. The resulting hybrid photoelectrodes are photoelectrocatalysts for CO₂ reduction in acetonitrile containing 2.0 M triethylamine and 2.0 M isopropanol, yielding formate with high selectivity (>96%) and current density (∼0.6 mA/cm²), excellent reproducibility, and a photovoltage of 280 mV at −1.75 V (versus ferrocenium/ferrocene) under 1 sun illumination. The applied potential is close to the equilibrium potential for CO₂ reduction to formate. This work presents rare examples of immobilized molecular catalysts for CO₂ reduction to formate and the first on semiconducting silicon.
Hong, Y. H.; Jia, X.; Stewart-Jones, E.; Kumar, A.; Wedal, J. C.; Alvarez-Hernandez, J. L.; Donley, C. L.; Gang, A.; Gibson, N. J.; Hazari, N. Houck, M.; Jeon, S.; Kim, J.; Koh, H.; Mayer, J. M.; Mercado, B. Q.; Nedzbala, H. S.; Piekut, N.; Quist, C.; Stach, E.; Zhang, Y. Photoelectrocatalytic reduction of CO₂ to formate using immobilized molecular manganese catalysts on oxidized porous silicon, Chem, 2025, 102462. https://doi.org/10.1016/j.chempr.2025.102462
