Heat-Driven Water Splitting

Source: “Low-Temperature, Manganese Oxide-Based, Thermochemical Water ­Splitting Cycle”

Mark Davis et al.

Proceedings of the National Academy of Sciences 109(24): 9260–9264

Results: A novel process for using heat to split water uses relatively low temperatures (850 °C versus well over 1,000 °C for earlier approaches) and doesn’t produce toxic or corrosive intermediate products.

Why it matters: If producing hydrogen through electrolysis can become greener and less expensive, it might be more cost-effective than getting hydrogen out of natural gas, which is a process that emits carbon dioxide. This will be especially important if automakers start selling large numbers of vehicles powered by hydrogen fuel cells.

Methods: The researchers developed a process that uses sodium carbonate and manganese oxide to help facilitate water-splitting reactions. These materials are modified by a series of chemical reactions that change the way they react with water, producing hydrogen gas in one step and oxygen in another. The reactions form a closed cycle: at the end of the process the materials are returned to their original state, so they can be used many times.

Next Steps: The researchers aim to lower the working temperatures still further, with the goal of making it practical to split water using waste heat from industrial processes and power plants.