Chemistry: Splitting water in microgravity

The light-driven splitting of water in near-zero gravity to produce hydrogen and oxygen is demonstrated in Nature Communications this week. The research may have applications for long-term space-faring journeys, where water could be used to produce both device-powering fuel and breathable oxygen.

Plants are able to convert light and water into fuel and oxygen. Scientists hope to mimic and improve upon this natural process using artificial photosynthesis for large-scale renewable energy utilization. Although this technology has experienced growth for Earth-bound applications, there has been no work exploring its use for long-term space voyages.

Katharina Brinkert and colleagues developed an efficiently operating photoelectrochemical cell capable of splitting water using light in near-zero gravity. The authors performed a series of experiments in a drop tower to simulate the near-zero gravity environment of space to explore how solar water splitting might operate in space. They found that the lack of gravity would reduce light-driven water splitting activities owing to limited bubble removal from surfaces. However, by adjusting the shape of nanoscale-features in the cell, the authors enabled bubble release, retaining water-splitting activities in low-gravity.

The authors suggest that this technology could lead to improvements and extensions of life support systems for long-duration space voyages. This work also provides insight into how terrestrial light-driven water-splitting devices could be improved.