The most significant challenge to renewables is energy storage, where hydrogen can play the role. However, the source of hydrogen element is mainly from water, which poses significant difficulty in this pathway due to the geographic mismatch between renewables distribution and freshwater availability.

Hereby, we employed a moisture collection plus electrolysis strategy to harvest hydrogen gas from the air directly, powered by renewables. Hygroscopic ionic solutions act as the water collector, which absorbs moisture at a substantial rate under a relative humidity of as low as 20%. A framework, Direct Air Electrolysis (DAE) module, is designed to capture water from the air and directly convert it to hydrogen by electrolysis. The power supplied to the DAE is coupled with renewables to generate green hydrogen.

Figure 1. A schematic diagram of the DAE

A scaled-up five DAE stacked prototype runs in an open environment with a high Faradaic efficiency of over 95%, with more than 99% hydrogen purity. Moreover, this DAE can work under a bone-dry environment with a relative humidity of as low as 4%, and can be easily scaled to provide H₂ to remote, (semi-) arid, and scattered areas. To our knowledge, this is the first report of the production of pure hydrogen directly from the air.

Figure 2. A photo of the five DAE stacked prototype