An international team from the University of Adelaide in Australia, Tianjin and Nankai Universities in China, and Kent State University in the United States found that a simple and inexpensive acid layer on the electrolyser’s catalyst could turn seawater into water with “almost 100% efficiency”. No preprocessing other than filtering is required.
A typical electrolyser catalyst may be made of cobalt oxide with chromium oxide on the surface, according to the team. Seawater usually either ruins these catalysts by severe erosion by chloride ions, or rakes them up with insoluble precipitates of magnesium and calcium that accumulate and block the electrodes.
However, the addition of a Lewis acid layer to the catalyst can trap sufficient negatively charged hydroxyl anions from seawater to create a strongly alkaline environment of pH 14 around the catalyst, allowing chloride to develop on the catalyst. substance attack and formation of deposits on electrodes.
Professor Shizhang Qiao said:
Associate Professor Yau Zheng added, “The performance of commercial electrolysers using our catalysts in seawater is close to the performance of platinum/iridium catalysts using highly purified deionized water as feedstock.”
Water scarcity, projected to affect two-thirds of the world’s population by 2025, will be evident over the coming decades.
However, if seawater can be used to produce large amounts of green hydrogen, wherever it is used, such as in fuel cells or combustion processes, it will eventually combine with oxygen and be released into the environment as fresh water. That is the desalination process. With clean energy bonus if desired.
The team says it is working to scale up the system for commercial scale electrolysers and is looking for industrial partners to start production.
The paper is available in the journal natural energy.
Source: University of Adelaide, South China Morning Post
