Formamide Electrosynthesis from Methanol and Ammonia in Water over Pr-Doped MnO2.

A rare earth element doping strategy is reported to boost the activity and enhance the stability of MnO2 for selective formamide production through electrocatalytic oxidation coupling (EOC) of methanol and ammonia. MnO2 doped with 1% Pr was selected as the best candidate with an optimized formamide yield of 211.32 μmol cm-2 h-1, a Faradaic efficiency of 22.63%, and a stability of more than 50 h. The easier formation of Mn6+ species and the lower dissolution rate of Mn species over Pr-doped MnO2 revealed by in situ Raman spectra were responsible for the boosted formamide production and enhanced stability. In addition, a two-electrode flow electrolyzer was developed to integrate EOC with C2H2 semihydrogenation for simultaneously producing value-added products in both the anode and cathode.