Role of surface defects in CO2 adsorption and activation on CuFeO2 delafossite oxide

The recycling of CO2 back into chemicals via photo-electrochemical cells represents a viable route to mitigate the global climate crisis of current days. In this paper we focus on the copper-iron delafossite oxide, CuFeO2, which has been proven to have suitable physico-chemical properties to photo-catalyze the carbon dioxide reduction to formic acid. The specific electronic and structural features that allow activating the highly stable CO2 molecule are dissected by exploiting state-of-the art first principles methods. The effects of surface oxygen vacancies as well as the different roles of copper and iron on the adsorption and the activation of carbon dioxide at the CuFeO2 most stable surface are analyzed. These results highlight the key role of oxygen defects in favoring the CO2 adsorption and in promoting the formation of a radical anion CO2[rad]− or a carbonate-like adsorbate so providing the scientific grounds for implementing new rational design strategies and improving the performances of CuFeO2-based photoelectrodes for CO2 reduction.