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

• Published in: Carbon energy Vol. 6; no. 6
• Main Authors: Choi, Hyung Wook, Lee, Hongdae, Lu, Jun, Bin Kwon, Seok, Jeong, Dong In, Park, Beum Jin, Kim, Jiwon, Kang, Bong Kyun, Jang, Gun, Yoon, Dae Ho, Park, Ho Seok
• Format: Journal Article
• Language: English
• Published: Wiley 01.06.2024
• Subjects: battery‐powered electrolyzers; hierarchical structure; Prussian blue analog; trifunctional electrocatalyst; zinc–air battery
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.505

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. The development of a hierarchical structure, comprising Co4N nanoparticles encapsulated by Fe‐embedded N‐doped carbon nanocubes (Co4N@Fe/N–C), has been successfully achieved. This innovative structure serves as a robust trifunctional electrocatalyst, demonstrating high efficiency in rechargeable zinc–air batteries and overall water‐splitting electrolyzers. The exceptional oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction activities of Co4N@Fe/N–C are attributed to the strategic formation of heterointerfaces and the modulation of local electronic structures.