Polymer Electrolyte Membrane Fuel Cells (PEM-FC) and Non-noble Metal Catalysts for Oxygen Reduction

Identification of the Catalytically Dominant Iron Environment in Iron- and Nitrogen-Doped Carbon Catalysts for the Oxygen Reduction Reaction

“…5,13−16 Therefore, FeNC catalysts are amorphous materials. 17,18 Nitrogen-coordinated metal ions are widely accepted as crucial for high activities 19−23 and are thus favored as catalytically active sites in the most recent ex situ characterization and in situ X-ray absorption spectroscopy (XAS) studies. 2,22,24−28 Although this group of catalysts has been known since the 1970s, 29 the understanding of the active site in terms of the iron coordination environment, the nature of the carbon matrix, and coordination of intermediates to the active site(s) remains incomplete.…”

“…FeNC catalysts are typically prepared by pyrolysis, e.g. , of an iron source, a zinc imidazole framework, and a secondary nitrogen precursor. ,− Therefore, FeNC catalysts are amorphous materials. , Nitrogen-coordinated metal ions are widely accepted as crucial for high activities − and are thus favored as catalytically active sites in the most recent ex situ characterization and in situ X-ray absorption spectroscopy (XAS) studies. ,,− Although this group of catalysts has been known since the 1970s, the understanding of the active site in terms of the iron coordination environment, the nature of the carbon matrix, and coordination of intermediates to the active site(s) remains incomplete. Such a detailed understanding is a prerequisite for the systematic optimization of the preparation methodology, targeting catalysts with high active site densities and turnover frequencies while avoiding catalyst degradation.…”

Correlations between Mass Activity and Physicochemical Properties of Fe/N/C Catalysts for the ORR in PEM Fuel Cell via 57Fe Mössbauer Spectroscopy and Other Techniques

“…It has been known for several years now that Me/N/C catalysts, prepared by a heat treatment of a source of a nonprecious metal, nitrogen, and carbon can be used as catalysts for ORR in PEM fuel cells. − Especially during the last 5 years, tremendous progress has been achieved regarding the improvement of the activity, performance and stability of these Me/N/C catalysts, where Me usually is either Fe and/or Co. − The best stability was demonstrated in 2011 by Fe/Co-PANI-C catalysts that exhibited good long-term performance for 4 weeks of potentiostatic measurement at 0.4 V . A first breakthrough in activity was reported for a Fe/N/C catalyst in 2009 .…”

Non Precious Catalysts for Fuel Cells - A Short Review on Mößbauer Spectroscopy of Fe-N-C Catalysts for ORR

“…Today's best performing NPMC are Fe-N-C catalysts. In addition to these, transition metal nitrides, carbides and oxides (or combinations of them) show promising results as well (2)(3).…”