Nonprecious transition metal nitrides as efficient oxygen reduction electrocatalysts for alkaline fuel cells.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35108056.
- Also identified by DOI 10.1126/sciadv.abj1584 and PMC identifier 8809680.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Hydrogen fuel cells have attracted growing attention for high-performance automotive power but are hindered by the scarcity of platinum (and other precious metals) used to catalyze the sluggish oxygen reduction reaction (ORR). We report on a family of nonprecious transition metal nitrides (TMNs) as ORR electrocatalysts in alkaline medium. The air-exposed nitrides spontaneously form a several-nanometer-thick oxide shell on the conductive nitride core, serving as a highly active catalyst architecture. The most active catalyst, carbon-supported cobalt nitride (Co<sub>3</sub>N/C), exhibited a half-wave potential of 0.862 V and achieved a record-high peak power density among reported nitride cathode catalysts of 700 mW cm<sup>-2</sup> in alkaline membrane electrode assemblies. Operando x-ray absorption spectroscopy studies revealed that Co<sub>3</sub>N/C remains stable below 1.0 V but experiences irreversible oxidation at higher potentials. This work provides a comprehensive analysis of nonprecious TMNs as ORR electrocatalysts and will help inform future design of TMNs for alkaline fuel cells and other energy applications.