engleski

Ultrasonic plasma engineering toward facile synthesis of single-atom MN4/N-doped carbon (M = Fe, Co) as superior oxygen electrocatalyst in rechargeable zinc-air batteries

As bifunctional oxygen evolution/reduction electrocatalysts, transition-metal-based singleatom-doped nitrogen-carbon (NC) matrices are promising successors of the corresponding noble- metal-based catalysts, offering the advantages of ultrahigh atom utilization efficiency and surface active energy. However, the fabrication of such matrices (e.g., well-dispersed single-atom-doped M-N4/NCs) often requires numerous steps and tedious processes. Herein, ultrasonic-plasma engineering allows direct carbonization in a precursor solution containing metal-phthalocyanine and aniline. When combining with the dispersion effect of ultrasonic waves, we successfully fabricated uniform single- atom M-N4 (M = Fe, Co) carbon catalysts with a production rate as high as 10 mg/min. The Co-N4/NC presented a bifunctional potential drop of ΔE = 0.79 V, outperforming the benchmark Pt/C-Ru/C catalyst (ΔE = 0.88 V) at the same catalyst loading. Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms. In a practical Zn-air battery test, the air electrode coated with Co-N4/NC exhibited a specific capacity (762.8 mAh/g) and power density (101.62 mW/cm2), exceeding those of Pt/C- Ru/C (700.8 mAh/g and 89.16 mW/cm2, respectively) at the same catalyst loading. Moreover, for Co-N4/NC, the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles. The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.

Single-atom-doped M-N4/NC catalyst ; Plasma engineering ; ORR/OER bifunctional activity ; DFT calculation ; Rechargeable Zn-air battery

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