Nitrogen and cobalt co-doped carbon nanotube films as binder-free trifunctional electrode for flexible zinc-air battery and self-powered overall water splitting

Developing effective and stable electrodes with foldable features to promote hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction are vital for fully realizing future flexible energy devices. However, combining three active composites into a single foldable electrode is still a challenge. Thereby, this work successfully fabricates a flexible trifunctional electrode based on self-supported N, Co co-doped carbon nanotubes (N, Co- CNTs). The obtained N, Co-CNTs possess favorable component-structure features, including heteroatom-doped structure and rich N content, which can simultaneously boost three crucial reactions. According to acid-washed experiment, the metallic cobalt cores are not directly attributed to catalytic activity. Moreover, As-assembled flexible zinc-air battery (ZAB) provides a high peak power density (114 mW cm(-2)) and long-term durability. Specially, this flexible ZAB reliably operates under external mechanical changes and an as-constructed water electrolyzer can be powered by two flexible ZABs in series.