Theory-Guided Regulation of FeN4 Spin State by Neighboring Cu Atoms for Enhanced Oxygen Reduction Electrocatalysis in Flexible Metal-Air Batteries

Iron, nitrogen-codoped carbon (Fe-N-C) nanocomposites have emerged as viable electrocatalysts for the oxygen reduction reaction (ORR) due to the formation of FeNxCy coordination moieties. In this study, results from first-principles calculations show a nearly linear correlation of the energy barriers of key reaction steps with the Fe magnetic moment. Experimentally, when single Cu sites are incorporated into Fe-N-C aerogels (denoted as NCAG/Fe-Cu), the Fe centers exhibit a reduced magnetic moment and markedly enhanced ORR activity within a wide pH range of 0-14. With the NCAG/Fe-Cu nanocomposites used as the cathode catalyst in a neutral/quasi-solid aluminum-air and alkaline/quasi-solid zinc-air battery, both achieve a remarkable performance with an ultrahigh open-circuit voltage of 2.00 and 1.51 V, large power density of 130 and 186 mW cm(-2), and good mechanical flexibility, all markedly better than those with commercial Pt/C or Pt/C-RuO2 catalysts at the cathode.

Automated summary

Iron, nitrogen-codoped carbon nanocomposites have been found to be effective electrocatalysts for the oxygen reduction reaction due to the formation of FeNxCy coordination moieties. Experimental and computational results show that incorporating single Cu sites can decrease the magnetic moment of the Fe centers and significantly enhance ORR activity over a wide pH range. When used as cathode catalysts in aluminum-air and zinc-air batteries, the Fe-N-C nanocomposites exhibit superior performance compared to commercial Pt/C or Pt/C-RuO2 catalysts.