New Environmentally-Friendly Technique Could Revolutionize How We Extract Hydrogen Gas From Water
Scientists have found a way to liberate hydrogen gas from water on an industrial scale without emitting excess carbon into the atmosphere. Their report, which was published in Nature Chemistry, could revolutionize industrial hydrogen production, and therefore, the way industries manufactures fertilizer and refined crude oil, both of which need the chemical.
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Molecular hydrogen, H2, cannot usually be found in pure-gas form, but instead, must be derived from water (H20) or Methane (CH4), which is a major component in natural gas. Producing industrial hydrogen from natural gas can cause massive global carbon emissions, as the hydrogen separates from the carbon. For these reasons, the nanotechnologists involved in the current study engineered an efficient and environmentally friendly catalyst for hydrogen production.
Through a process known as electrolysis, which entails sending electrical currents through metallic electrodes covered in water, the researchers were able to break the bonds between hydrogen and oxygen, and create molecular hydrogen. But first, they had to find a cheaper metal electrode to act as a catalyst for the process. Platinum, the most effective electrode, is expensive and costs $1 to $2 per kilogram to produce hydrogen from methane. With the global consumption of hydrogen at 55 billion kilograms per year, any new electrolysis process must not just be green but also be cheaper than electrolysis based on platinum.
The researchers used a chemical known as molybdenum sulfide (moly sulfide), which is typically part of the oil-refining process, as their catalyst. First, however, they had to re-engineer its atomic structure. In its usual crystal form, each sulfur atom on the surface is attached to three molybdenum atoms underneath - making it ineffective as a conductor.
Some surface atoms on the edges of the crystal, however, are bound to just two molybdenum atoms, and are much more effective in forming H2.
Jakob Kibsgaard, a postdoctoral researcher at Stanford University, synthesized nano-clusters of this special moly sulfide, and then deposited them onto a sheet of graphite. Together, these materials formed a cheap but efficient electrode comparable to platinum. Finally, the researchers tested their system, and it worked.
The researchers have also worked out the commercial viability of using their system to produce hydrogen. Industry-scale electrolysis is possible with their system at costs ranging from $1.60 to $10.40 per kilogram, which they say is competitive at the low end.
"There are many pieces of the puzzle still needed to make this work, and much effort ahead to realize them," Thomas Jaramillo, assistant professor of chemical engineering at Stanford, said in a statement. "However, we can get huge returns by moving from carbon-intensive resources to renewable, sustainable technologies to produce the chemicals we need for food and energy."
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