Submerged-Plant-Inspired Five-Level-Synergetic hierarchical Single-Fe-Atom-Doped Micro-Electrodes for High-Performance multifunctional electrocatalysis

Abstract

Multifunctional electrocatalyst delivers powerful ability in energy storage and conversion systems to relieve energy crisis nowadays. However, due to the complexity of material synthesis and electrode construction, it still remains a challenge to achieve multifunctionality while maintaining high catalytic activity. In this work, inspired by the unique structure of submerged plants, three dimensional hierarchical electrodes were constructed via 3D printing and applied in water splitting devices and Zn-air batteries to emulate the photosynthesis and respiration, respectively. The fabricated electrodes possess surface single-Fe-atom-doped Ni/Ni(OH)2 and embedded Fe-doped carbon nanotubes (Fe-CNTs), which contribute to water splitting and oxygen reduction reaction (ORR), respectively. Benefiting from the hierarchical synergetic structure and appropriate location of active center, overpotentials of 175 mV and 108 mV were respectively achieved for oxygen evolution reaction and hydrogen evolution reaction to reach 30 mA cm−2 in 1 M KOH solution, and corresponding overall water splitting required a low voltage of 1.51 V. In addition, the assembled Zn-air battery achieved a power density of 143.8 mW cm−2. Overall, the fabricated 3D electrodes presented remarkable potential for overall water splitting and Zn-air batteries, and this strategy also put forward a new avenue for designing and constructing high-performance trifunctional electrocatalyst electrodes.