Hydrothermal CO2 Reduction with Iron to Produce Formic Acid

CO₂ is attractive as a renewable carbon source and an environmentally friendly chemical reagent; however, a highly effective and simple method of CO₂ conversion is critical to CO₂ utilization. Here, a novel and highly efficient CO₂ reduction with a commercially available metal of Fe without adding any other catalyst was proposed, producing formic acid with an excellent yield of 92%. NaHCO₃, as a CO₂ source, was found to remarkably improve Fe oxidation in water for producing hydrogen, which not only promotes CO₂ hydrogenation but also results in in situ reduction of Fe₃O₄ into a high catalytic activity of Fe₃O_4–x , leading to an autocatalytic process.