A tungsten-mediated closed cycle of reactivity for the reduction of CO2 to CO

The recycling of CO2 by reduction to CO is an important objective in the context of renewable carbon feedstock chemicals. A tungsten-mediated reduction of CO2 to CO reported by Mayer and coworkers has been re-examined, and it is shown that a series of four well-defined stoichiometric steps can be executed which form a closed cycle and sum as CO2 + 2H(+) + 2e(-) -> CO + H2O. Energetic parameters of this system are probed by cyclic voltammetry, by calculations of gas-phase reaction enthalpies for each of the four steps, and by calculation of the W O bond dissociation energy for the tungsten species that results from oxidation addition of CO2.