Chemical engineers have found a 30-year-old recipe that stands to make future hydrogen production cheaper and greener. The recipe has led researchers to a way to liberate hydrogen from water via electrolysis using molybdenum sulfide – moly sulfide for short – as the catalyst in place of the expensive metal platinum.
While hydrogen is relatively abundant here on Earth, it is generally bound to either carbon or oxygen to form methane and water respectively. Producing hydrogen currently involves liberating it from methane at a cost of between US$1 and $2 per kilogram. And the world’s hunger for hydrogen continues to grow, currently we consume 55 billion kilograms of the element per year, making freeing it from methane or water big business. And with numerous automakers dipping their tires in the hydrogen fuel waters, it’s set to get much bigger.
The other side of the equation is the by-product of production. When hydrogen is freed from methane the waste product is carbon, which is released into the atmosphere furthering climate change. Producing hydrogen from water on the other hand produces oxygen as waste.
The limiting factor to getting hydrogen from water in the past has been the expense of electrolysis, the process were hydrogen atoms are liberated from their bond with oxygen in water by passing an electrical current through an electrode immersed in the water. The main expense in this process was the use of platinum as the electrode. The efficiency of platinum to catalyze the breaking of hydrogen-oxygen bonds in water to free the hydrogen until now has been unmatched.
Enter moly sulfide. Since World War II, moly sulfide has been used by petroleum engineers in the refinement of oil. It was thought to be inefficient for the electrolysis of hydrogen from water due to the molecular structure at its surface.
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Could moly sulfide be the key to cheaper hydrogen production?