Defect-activated ternary carbon composite: A multifunctional electrocatalyst for efficient oxidation of water, urea, glucose, ORR, and zinc-air batteries

Designing a low-cost multifunction electrocatalyst that can synergistically catalyze multiple reactions in alkaline media while operative for long periods is of paramount importance for the hydrogen economy. Particularly, defect-activated electrocatalysts can significantly improve electrolytic performance by altering their chemical properties and electronic structures. However, developing defect-rich electrocatalysts with multiple active sites for efficient electro-oxidation of water remains challenging. In this respect, we present a straightforward strategy to design a defect-activated multifunctional ternary carbon composite by integrating graphene oxide (GO), Mxene (Mx), and graphitic carbon nitride (CN). Benefiting from the well-integrated 2D interfacial coupling of different carbon nanostructures, carbon composite has several advantageous properties including superior electric conductivity, higher specific surface area, activated surface defects, and highly accessible multicomponent surface-active sites. In addition, carbon composite exhibited macroporous 3D architecture for free migration of oxygen species and electrons. Accordingly, the carbon composite served as a multifunctional electrocatalyst in alkaline media, displaying superior electrolytic activities toward oxygen evolution reaction (OER), urea oxidation reaction (UOR), glucose oxidation reaction (GOR), and oxygen reduction reaction (ORR). Moreover, the Zn-air batteries (ZABs) fabricated with Zn anode and carbon composite as air-cathode demonstrated to have a high-power density, high discharge voltage, and excellent cycling stability in alkaline media. The exceptional electrolytic performance is attributed to the defect-rich interfaces and the synergistic interactions between the multi-components of carbon composite, which not only facilitate free accessible volume for rapid diffusion of oxygen-related species but also maintain the structural integrity during the reaction, thus allowing its comparable fast reaction kinetics. Overall, this work presents a simple and scalable strategy to design an efficient, stable, and eco-friendly multifunctional electrocatalyst that has the potential to be used in a wide range of applications in energy conversion and storage.