Green Rust: A Potent Reductant for Unassisted Conversion of CO to Multicarbon Liquid Products

Direct low-pressure, low-temperature conversion of CO to stable multicarbon liquid products is highly desirable because of the toxic nature of the gas. However, the process is challenging due to the high stability of CO molecules and thus requires high energy in the form of heat or an applied electric field to achieve good conversion efficiencies on catalysts explored until date, indicating the low intrinsic activity of these materials for CO activation. Here, we report on a form of rust, namely green rust (GR), a Fe corrosion product that forms under anaerobic conditions, as a highly potent reductant capable of spontaneously reducing CO to multicarbon liquid products such as acetone (C3) and others on a time scale of minutes without external energy input. Our results show that the high intrinsic activity of GR is probably due to its unusual band structure with an electron affinity of ∼3.2 eV, which is the lowest among the common minerals of oxides and sulfides in the natural environment.