Separating hydrogen and oxygen evolution in alkaline water electrolysis using nickel hydroxide.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 27199009.
- Also identified by DOI 10.1038/ncomms11741 and PMC identifier 4876480.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Low-cost alkaline water electrolysis has been considered a sustainable approach to producing hydrogen using renewable energy inputs, but preventing hydrogen/oxygen mixing and efficiently using the instable renewable energy are challenging. Here, using nickel hydroxide as a redox mediator, we decouple the hydrogen and oxygen production in alkaline water electrolysis, which overcomes the gas-mixing issue and may increase the use of renewable energy. In this architecture, the hydrogen production occurs at the cathode by water reduction, and the anodic Ni(OH)2 is simultaneously oxidized into NiOOH. The subsequent oxygen production involves a cathodic NiOOH reduction (NiOOH→Ni(OH)2) and an anodic OH(-) oxidization. Alternatively, the NiOOH formed during hydrogen production can be coupled with a zinc anode to form a NiOOH-Zn battery, and its discharge product (that is, Ni(OH)2) can be used to produce hydrogen again. This architecture brings a potential solution to facilitate renewables-to-hydrogen conversion.