The research from Rice University in Texas could also extend the lifetime of catalysts by improving efficiencies and reducing costs for industrial processes hindered by coking.
The new copper-rhodium photocatalyst features an antenna-reactor design that, when exposed to a specific wavelength of light, breaks down methane and water vapour without external heating into hydrogen and carbon monoxide.
In a statement, Peter Nordlander, Rice’s Wiess Chair and Professor of Physics and Astronomy, said: “This is one of our most impactful findings so far, because it offers an improved alternative to what is arguably the most important chemical reaction for modern society. We developed a completely new, much more sustainable way of doing SMR.”
Nordlander and Naomi Halas, Rice University Professor and the Stanley C. Moore Professor of Electrical and Computer Engineering, are the corresponding authors on a study about the research published in Nature Catalysis.
The new SMR reaction leverages the 2011 discovery from the Halas and Nordlander labs at Rice that plasmons can emit ‘hot carriers’ or high-energy electrons and holes that can be used to drive chemical reactions.
“We do plasmonic photochemistry - the plasmon is really our key here - because plasmons are really efficient light absorbers, and they can generate very energetic carriers that can do the chemistry we need them to much more efficiently than conventional thermocatalysis,” said first author Yigao Yuan, a Rice doctoral student.
The new catalyst system uses copper nanoparticles as its energy-harvesting antennae. However, since the copper nanoparticles’ plasmonic surface does not bond well with methane, rhodium atoms and clusters were inserted as reactor sites. The rhodium specks bind water and methane molecules to the plasmonic surface, using the energy of hot carriers to fuel the SMR reaction.
“We tested many catalyst systems, but this one turned out to work best,” said Yuan.
According to Rice, the research also shows that the antenna-reactor technology can overcome catalyst deactivation due to oxidation and coking by employing hot carriers to remove oxygen species and carbon deposits.
Nordlander said the key to this ‘remarkable effect was the clever placement of the rhodium,’ which is spread sparingly and unevenly across the surface of the nanoparticles.
Hydrogen is mainly produced in large, centralised facilities, requiring the gas to be transported to its point of use. In contrast, light-driven SMR allows for on-demand hydrogen generation. “This research showcases the potential for innovative photochemistry to reshape critical industrial processes, moving us closer to an environmentally sustainable energy future,” said Halas.
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