Trifunctional robust electrocatalysts based on 3D Fe/N-doped carbon nanocubes encapsulating Co₄N nanoparticles for efficient battery-powered water electrolyzers

초록

Herein, we have designed a highly active and robust trifunctional electrocatalyst derived from Prussian blue analogs, where Co4N nanoparticles are encapsulated by Fe embedded in N-doped carbon nanocubes to synthesize hierarchically structured Co4N@Fe/N-C for rechargeable zinc-air batteries and overall water-splitting electrolyzers. As confirmed by theoretical and experimental results, the high intrinsic oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction activities of Co4N@Fe/N-C were attributed to the formation of the heterointerface and the modulated local electronic structure. Moreover, Co4N@Fe/N-C induced improvement in these trifunctional electrocatalytic activities owing to the hierarchical hollow nanocube structure, uniform distribution of Co4N, and conductive encapsulation by Fe/N-C. Thus, the rechargeable zinc-air battery with Co4N@Fe/N-C delivers a high specific capacity of 789.9 mAh g(-1) and stable voltage profiles over 500 cycles. Furthermore, the overall water electrolyzer with Co4N@Fe/N-C achieved better durability and rate performance than that with the Pt/C and IrO2 catalysts, delivering a high Faradaic efficiency of 96.4%. Along with the great potential of the integrated water electrolyzer powered by a zinc-air battery for practical applications, therefore, the mechanistic understanding and active site identification provide valuable insights into the rational design of advanced multifunctional electrocatalysts for energy storage and conversion.

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