Metal Single-Site Molecular Complex-MXene Heteroelectrocatalysts Interspersed Graphene Nanonetwork for Efficient Dual-Task of Water Splitting and Metal-Air Batteries

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (Fe-MC)-carbide MXene (Mo2TiC2Tx) uniformly embedded in a 3D graphene-based hierarchical network (GrH) is rationally designed. The coexistence of Fe-MC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the Fe-MC-MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al-air batteries derived from Fe-MC-MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm(-2), respectively. Impressively, the liquid-state Zn-air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm(-2) and 1.86 V at 0.4 A cm(-2) in 30 wt.% KOH at 80 degrees C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.

Automated summary

In this study, a novel multifunctional electrocatalyst composed of Fe-MC and MXene embedded in GrH was designed. The catalyst exhibited excellent catalytic activities and stability for various reactions, including ORR, OER, and HER. Practical tests demonstrated high power densities and cycling stability in Zn/Al-air batteries and alkaline water electrolyzers.