Catalysis stability enhancement of Fe/Co dual-atom site via phosphorus coordination for proton exchange membrane fuel cell

Non-precious metal catalysts (NPMCs) are promising low-cost alternatives of Pt/C for oxygen reduction reaction (ORR), which however suffer from serious stability challenge in the devices of proton-exchange-membrane fuel cells (PEMFC). Different from the traditional strategies of increasing the degree of graphitization of carbon substrates and using less Fenton-reactive metals, we prove here that proper regulation of coordination anions is also an effective way to improve the stability of NPMC. N/P co-coordinated Fe-Co dual-atomic-sites are constructed on ZIF-8 derived carbon support using a molecular precursor of C34H28Cl2CoFeP2 and a "precursor-preselected" method. A composition of FeCoN5P1 is infered for the dual-atom active site by microscopy and spectroscopy analysis. By comparing with N-coordinated references, we investigate the effect of P-coodination on the ORR catalysis of Fe-Co dual-atom catalysts in PEMFC. The metals in FeCoN5P1 have the lower formation energy than those in the solo N-coordinated active sites of FeCoN6 and FeN4, and exhibits a much better fuel cell stability. This anion approach provides a new way to improve the stability of dual-atom catalysts.