E. coli-derived carbon with nitrogen and phosphorus dual functionalities for oxygen reduction reaction

• Direct carbonization of Escherichia coli cells to heterogeneous carbon materials.
• Carbon materials with nitrogen and phosphorus dual functionalities.
• Metal-free carbon catalyst with excellent catalytic activity for oxygen reduction reaction.

Nitrogen and phosphorus dual doped carbon materials have shown competing catalytic activity as metal-free catalysts for oxygen reduction reaction (ORR). Prevailing methods to synthesize such carbon catalysts require high purity chemicals and gases, excessive amount of strong acids and bases, or costly organic precursors. Here, we show that Escherichia coli (E. coli), a common bacterium, can be used as a novel precursor to synthesize heterogeneous carbon materials with nitrogen and phosphorus dual functionalities by direct carbonization. The E. coli derived carbon has a large surface area up to 636 m2/g, and is comprised of up to 7.64 at% nitrogen and 8.53 at% phosphorus. The carbon material obtained at an optimum carbonization condition of 1000 °C for 2 h shows excellent catalytic performances, comparable to that of a 20 wt% Pt-C catalyst, with ∼50% higher limiting current density, for ORR in near four-electron transfer processes and excellent durability. The outstanding electrocatalytic performances are credited to the fine tuning of nitrogen species by carbonization conditions and the synergy between nitrogen and phosphorus dual functionalities. Our work demonstrates the great potential of using bacterial cells as a novel green precursor to synthesize heterogeneous carbon materials with nitrogen and phosphorus dual functionalities as electrocatalytic catalysts for ORR.

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