Transformation of greenhouse gas CO2 to fuel has attracted much attention since it contributes to CO2 elimination and development of sustainable energy system. Formic acid is one important product since it can be used in direct FA fuel cell. In addition, it is also a promising hydrogen carrier because it is nontoxic, biodegradable, and liquid at room temperature. Inspired by the active cite of [Fe] hydrogenase, we have developed proton-responsive complexes for efficient interconversion between CO2/H2 and formic acid/formate in water. In CO2 hydrogenation, pendent OH group is demonstrated to be crucial for H2 heterolytic cleavage and favorable for hydride formation. While in FA dehydrogenation, pendent OH group changed rate determining step of the reaction. Herein, we report our recent studies on catalytic CO2 hydrogenation and dehydrogenation of formic acid using novel proton responsive complexes. A series of proton-responsive Ir complexes were designed and synthesized with hydroxyl substituted N,N-bidentate ligands. These complexes were demonstrated to be highly efficient in CO2 hydrogenation and dehydrogenation of HCO2H in water. A novel complex provided an initial TOF as high as 65000 h−1 at 60 °C. This result suggested that the complex is the most efficient complex yet reported. The mechanistic insight will also be discussed.

Bio-inspired complexes for efficient catalytic interconversion between CO2/H2 and formic acid

256th National Meeting (2018)

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