Spatial porosity design of Fe–N–C catalysts for high power density PEM fuel cells and detection of water saturation of the catalyst layer by a microwave method

Abstract

Porous structure is essential for non-precious metal catalysts (NPMCs) to achieve high utilization of active sites and efficient mass transfers in proton exchange membrane fuel cells (PEMFC). Here, submicron Fe-N-C...

Exploring Durable Single-Atom Catalysts for Proton Exchange Membrane Fuel Cells

“…Metal–nitrogen–carbon (M–N–C, M = Fe, Co, Mn, etc.) catalysts with single-atom M–N x active sites have emerged as promising low-cost ORR catalysts. − Among all M–N–C catalysts, Fe–N–C has attracted most of the attention because of their highest activity in acidic media. − The past decade has witnessed rapid progress in the activity of Fe–N–C, which is now approaching that of Pt/C catalyst. − While this is encouraging, their stability in PEMFC is still poor. , The stability of Fe–N–C is usually measured by chronoamperometry at the cell voltage of 0.4–0.7 V. A performance loss of 40–80% typically occurs during the first 100 h of fuel cell testing. This is a far cry from the U.S. Department of Energy’s durability target for light-duty vehicle applications (8 000 h with <10% performance drop) .…”

Electronic Enhancement Engineering by Atomic Fe–N4 Sites for Highly‐Efficient PEMFCs: Tailored Electric‐Thermal Field on Pt Surface

“…The high‐resolution N 1s spectrum can be fitted into binding energies of 398.6 (pyridinic N), 399.6 (pyrrolic N), 401.2 (graphitic N), and 403.3 eV (chemisorbed N) (Figure 2c). It has been well‐acknowledged that both pyridinic N and pyrrolic N are responsible for the formation of Fe–N 4 species, [ 41,46 ] while graphitic N facilitates the 4e ORR process according to our already published work. [ 31 ] X‐ray absorption near‐edge structure (XANES) spectroscopy and extended X‐ray absorption fine structure (EXAFS) spectroscopy, were used to verify the atomic dispersion of Fe species and their coordination structure.…”

Identifying Activity Trends for the Electrochemical Production of H2O2 on M–N–C Single-Atom Catalysts Using Theoretical Kinetic Computations

“…In the high-resolution spectrum of Co (Figure 1e), the two main representative peaks at 779.9 and 782.2 eV can be assigned to Co 3+ and Co 2+ of Co 2p 3/2 , respectively. 34 Similarly, the high-resolution spectra and fittings of Fe and Mn reveal the Fe 2+ and Fe 3+ oxidation states in Fe−N−C 47 and the Mn 2+ oxidation state in Mn−N−C (Figure S11). 48 No M 0 states were found, indicating the absence of metal nanoparticles and clusters in the synthesized M−N−C catalysts, which is consistent with the XRD and HADDF-STEM results.…”