Phosphate tolerance of nitrogen-coordinated-iron-carbon (FeNC) catalysts for oxygen reduction reaction: A size-related hindrance effect

Single-Atom Iron-Based Electrocatalysts for High-Temperature Polymer Electrolyte Membrane Fuel Cell: Organometallic Precursor and Pore Texture Tailoring

“…Jain and co-workers have attempted to resolve this inconsistency by studying the effect of carbon supports used on the resilience of FeNC catalysts against the phosphate poisoning under ORR conditions. 68 The results obtained in their study point to "size-related hindrance effect" with respect to the size of the poisoning probe molecules as well as the size and number of pores present in the carbon support prepared via high-temperature pyrolysis. They have systematically explored the effect of nature of carbon support on the immunity towards phosphate poisoning using two different carbon supports: Black Pearls (FeNC-BP) and Vulcan carbon (FeNC-VC).…”

“…The effect of phosphate anion on the ORR activity of Fe−N−C-type catalysts in PEMFCs has been discussed in the literature. − The Fe−N−C-type catalysts have been known to have good resistance to the poisoning in the presence of phosphoric acid, unlike Pt/C which exhibits a significant loss in ORR activity after exposure to phosphate anions. Zelenay et al, reported that while the Fe–N–C catalyst (PANI–Fe–C) has high ORR activity in phosphoric acid electrolyte, the ORR half-wave potential of the catalyst was ∼40 mV lower than the one conducted in sulfuric acid electrolyte .…”

“…Based on the above summary, it can be concluded that the resistance of Fe−N−C catalysts against phosphate poisoning is dependent on different parameters such as the precursors used, the methodology adopted for the synthesis of these materials, and structure (shape, porosity, and surface characters) of carbon supports, resulting in still some inconsistency in literature reports. Jain and co-workers have attempted to resolve this inconsistency by studying the effect of carbon supports used on the resilience of FeNC catalysts against the phosphate poisoning under ORR conditions . The results obtained in their study point to “size-related hindrance effect” with respect to the size of the poisoning probe molecules as well as the size and number of pores present in the carbon support prepared via high-temperature pyrolysis.…”

“…Fe–N–C catalysts have been rarely investigated with full details in HT-PEMFC for practical application so far. − Herein, the MEAs were fabricated using LEDFe5-NH 3 as a cathode for H 2 /O 2 HT-PEMFC performance. Figure c illustrates the polarization curves and power density plots of HT-PEMFCs with LEDFe5-NH 3 and commercial Pt/C each as a cathodic catalyst.…”

Axial ligand promoted phosphate tolerance of an atomically dispersed Fe catalyst towards the oxygen reduction reaction

“…[5][6][7][8][9][10][11][12][13] Among NPMCs, Fe-N-C catalysts featuring an iron center coordinated with nitrogen have shown unique activity for the ORR, as well as being one of the few NPMCs that can withstand strong acidic media, and have received extensive attention as cathodic catalysts for low-temperature PEMFCs. [14][15][16][17][18][19][20][21] The active research on Fe-N-C catalysts in low-temperature PEMFCs implies great opportunities for application in PA-PBI fuel cells, attracting a surge of studies on Fe-N-C catalysts for the ORR in the presence of PA. [22][23][24][25] Although it is widely accepted that Fe-N-C catalysts are resistant to phosphate anions, the origin of the anti-poisoning of phosphate anions of the Fe-N-C catalysts remains unknown and controversial, owing to the diverse active site congurations reported in the literature based on the synthesis routes. Strickland et al proposed that the physical isolation of the encapsulated Fe particles by using graphitic layers protects the Fe active sites from phosphate anions in a FePhen@MOF-ArNH 3 catalyst composed of Fe/Fe x C/Fe x N particles embedded in graphitic carbon layers doped with nitrogen.…”