An Ion-Imprinting Derived Strategy to Synthesize Single-Atom Iron Electrocatalysts for Oxygen Reduction.

Carbon-based single-atom catalysts (CSACs) have recently received 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 derived strategy is proposed to synthesize CSACs, in which isolated metal-nitrogen-carbon (Me-N4 -Cx ) moiety covalently binds 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 is synthesized by using this ion-imprinting derived strategy. Experimental results and theoretical calculations demonstrate high concentration of single FeN4 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.