CO₂ Hydrogenation to Formic Acid by a Molecular Catalyst [B₁₂X₁₁]⁻ (X = F, Cl, Br, and I)

Catalytic hydrogenation of CO₂ into formic acid (HCOOH) not only reduces the emission of greenhouse gases but also is profitable for the application of formic acid in chemical industries, electricity generation, and H₂ storage and transportation. An effective, cheap, and recyclable catalyst for the conversion of CO₂ to HCOOH is urgently required and has attracted tremendous attention over the past few decades. In this work, we proposed a potential molecular catalyst [B₁₂X₁₁]^- (X = F, Cl, Br, I) toward the thermochemical CO₂ conversion to HCOOH through density functional theory calculations in combination with infrared photodissociation (IRPD) spectroscopy. Both H₂ first adsorption and CO₂ first adsorption pathways have been studied. The most favorable pathway proceeds through CO₂ adsorption and activation by the Lewis acidic boron vertex, forming a B-OCO bond; then, the HCOO* intermediate forms with the assistance of the ligand X atoms. The removal of HCOOH is the rate-determining step of the reaction. Our finding of the molecular catalyst [B₁₂X₁₁]^- for CO₂ conversion to HCOOH may provide a path toward the development of new catalysts.