Issue 47, 2021

Fe–N–C electrocatalysts in the oxygen and nitrogen cycles in alkaline media: the role of iron carbide

Abstract

Fe–N–C electrocatalysts hold a great promise for Pt-free energy conversion, driving the electrocatalysis of oxygen reduction and evolution, oxidation of nitrogen fuels, and reduction of N2, CO2, and NOx. Nevertheless, the catalytic role of iron carbide, a component of nearly every pyrolytic Fe–N–C material, is at the focus of a heated controversy. We now resolve the debate by examining a broad range of Fe3C sites, spanning across many typical size distributions and carbon environments. Removing Fe3C selectively by a non-oxidizing acid reveals its inactivity towards two representative reactions in alkaline media, oxygen reduction and hydrazine oxidation. The activity is assigned to other pre-existing sites, most probably Fe–Nx. DFT calculations prove that the Fe3C surface binds O and N intermediates too strongly to be catalytic. By settling the argument on the catalytic role of Fe3C in alkaline electrocatalysis, we hope to spur innovation in this critical field.

Graphical abstract: Fe–N–C electrocatalysts in the oxygen and nitrogen cycles in alkaline media: the role of iron carbide

Supplementary files

Article information

Article type
Paper
Submitted
08 Aug 2021
Accepted
01 Oct 2021
First published
01 Oct 2021

Phys. Chem. Chem. Phys., 2021,23, 26674-26679

Fe–N–C electrocatalysts in the oxygen and nitrogen cycles in alkaline media: the role of iron carbide

T. Y. Burshtein, D. Aias, J. Wang, M. Sananis, E. M. Farber, O. M. Gazit, I. Grinberg and D. Eisenberg, Phys. Chem. Chem. Phys., 2021, 23, 26674 DOI: 10.1039/D1CP03650E

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