A research team led by Prof. YIN Huajie from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has developed a solar-powered system that produces green hydrogen directly from atmospheric moisture without relying on external water or energy sources. 

The results were published in Advanced Materials.

Proton exchange membrane water electrolysis (PEMWE) technology is a primary method for producing green hydrogen and has received significant attention due to its high efficiency and high-purity hydrogen output. However, PEMWE heavily relies on high-purity water as a reaction material, which limits its application in regions with water scarcity. Atmospheric water harvesting (AWH) is an emerging approach to obtaining pure water and a promising solution to the water shortage issue in green hydrogen production.

In this study, the researchers developed a self-sustaining system that couples photothermal atmospheric water harvesting with proton exchange membrane electrolysis. 

The researchers used hierarchically porous carbon as an adsorbent to capture moisture from the air, which is evaporated by solar heat and fed into a custom-built electrolyzer for hydrogen production. The porous material was fabricated through template synthesis and calcination, followed by surface oxidation to improve water affinity. 

It demonstrates remarkable performance. Even under low humidity conditions (as low as 20%), it maintains stable water collection and evaporation performance. Under 40% humidity, the system achieved a hydrogen production rate of nearly 300 mL per hour, demonstrating excellent cycle stability and long-term reliability. 

Field tests confirmed that the system can produce green hydrogen continuously using only solar energy with zero carbon emissions and no external energy input.

This work provides a new pathway for sustainable hydrogen production in water-scarce regions, according to the researchers. 

This study was supported by the National Natural Science Foundation of China and the Collaborative Innovation Program of Hefei Science Center.

Self-sustaining air water harvesting and proton exchange membrane water electrolysis based on ordered porous carbon. (Image by YIN Huajie)