PNNL

Abstract

Carbon-based single-atom catalysts (CSACs) have recently attracted extensive attention in catalysis research. However, the preparation process of CSACs involves a high-temperature treatment, during which metal atoms are mobile and aggregated into nanoparticles, detrimental to the catalytic performance. Herein, an ion imprinting strategy was proposed to synthesize CSACs, in which isolated metal-nitrogen-carbon (Me-N4-Cx) moiety was covalently bonding oxygen atoms in Si-based molecular sieve frameworks. Such a feature makes Me-N4-Cx moiety well protected/confined during the heat-treatment, resulting in the final material enriched with single-atom metal active sites. As a proof-of-concept, a single-atom Fe-N-C catalyst was fabricated by using this ion imprinting strategy. Experimental results and theoretical calculations demonstrated that high concentrations of single Fe active sites distributed in this catalyst, resulting in an outstanding oxygen reduction reaction (ORR) performance with a half-wave potential of 0.908 V in alkaline media.