The development of robust and efficient trifunctional catalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen reaction (HER) is central to regenerative metal-air batteries and overall water splitting. It is still a big challenge to achieve an efficient integration of three functions in one freestanding electrode. Herein, a facile and upscalable strategy is demonstrated, to construct cobalt nanoparticle-encapsulated 3D conductive films (Co/CNFs), which were induced by in situ solid diffusion from bulk cobalt metal. Under high-temperature, volatile cobalt species from bulk cobalt foil are trapped by the contacted nitrogen-rich carbons, followed by catalytic growth of interconnected carbon tubes, forming the 3D structured film. This resulting film can be directly preformed as self-supporting and binder-free electrode, which simultaneously facilitates the ORR, OER, and HER with excellent activities and superior stability. Furthermore, such "all-in-one" film also exhibits remarkable performance for Zn-air batteries and overall water splitting, demonstrating its feasibility for practical applications.
Keywords: Zn-air batteries; electrocatalysis; self-supporting film; solid diffusion; water splitting.
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.