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

The table of contents: We propose a facile strategy to design a flexible trifunctional electrode by directly growing N, Co dual-doped carbon nanotube (N, Co-CNT) on carbon cloth substrate. The obtained electrode with excellent activity and desired stability can fulfill efficient water splitting device, highly bendable zinc-air batteries, and an integrative power-to-gas system. [Display omitted] •A simple strategy was developed to synthesis N and Co co-doped carbon nanotube (N, Co-CNT) films on flexible carbon cloth.•Removing cobalt cores of cobalt carbon core-shell structure does not result in the degeneration of trifunctional activity.•Flexible Zn-air battery assembled by N, Co-CNT displayed excellent battery performance and hold superb flexibility.•An electrolyzer powered by flexible zinc-air batteries system was successfully conducted to effectively catalyze the water. 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.