Enhancing Propanol Production from CO2 Reduction with a Terbium-Doped Copper Nitride Electrocatalyst

Propanol is one of the most complex products obtained from CO2 electroreduction (CO2R). Being an interesting precursor for synthetic fuels and a feedstock for the chemical industry, its electrochemical production has recently raised increasing interest. However, low selectivity for propanol has been achieved so far. Here, via exploring a variety of original lanthanide-doped copper nitride materials, we identified and characterized terbium-doped copper nitride as the most selective catalyst for propanol formation. It allowed CO2R to yield propanol with a Faradaic efficiency of 27% at a high current density of 300 mA cm-2 within a neutral (KHCO3 electrolyte) flow cell, surpassing the performance of previous CO2R catalysts. The high density of undercoordinated nitride-derived Cu sites, combined with the increased oxophilicity of the surface, likely promoted the selectivity toward alcohols. Thorough DFT calculations showed that Tb doping increased the affinity for oxygenate-associated C2* intermediates and lowered the free-energy barrier for reactions coupling the latter with CO* toward propanol.