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Gold-MXene catalyst converts nitrate to ammonia using sunlight and 1.5 volts
Crucially, not only can the absorbed sunlight be used to stimulate the chemical reaction, but the heat generated in the process can also be used. In this way, sunlight has a double effect, significantly increasing efficiency. The findings are published in the journal Advanced Functional Materials.
Special material for more energy-efficient ammonia production
"Converting sunlight into chemical energy by using suitable catalysts is a well-developed strategy," says Professor Günther Rupprechter from the Institute of Materials Chemistry at TU Wien. "The problem is that most of the time, a large part of the sun's energy is lost immediately as heat, and only a small part of the energy is actually used for the chemical reaction you want."
To change this, the team combined several effects in an unusual way: In a new material, light, heat and electricity interact optimally. The team combined MXene (pronounced "Maxeen"), a special material composed mainly of carbon and titanium, with gold nanoparticles. The MXene consists of lamellae of atomically thin layers parallel to each other, which act as "nanoantennas" and capture light. The gold nanoparticles are where the actual chemical reaction takes place.
Different effects bring electrons to the gold particles
The MXene lamellae have special electronic properties: "When sunlight falls on these lamellae, the electrons in the material oscillate collectively back and forth, like a swing," Rupprechter explains. "These oscillations are called plasmons."
The energy of this rocking motion must now be transported to the gold nanoparticles. This happens through two different effects: First, individual electrons can be strongly accelerated, causing them to move at high speed. Second, an important temperature effect also comes into play: "The plasmons heat up the MXene, and when the material heats up, the heat spreads along the lamellar direction," explain Xingda An and Le He from Soochow University.
The gold nanoparticles, on the other hand, are cooler, and additional energy can be obtained from this temperature difference. The so-called Seebeck effect ensures that the temperature difference between MXene and gold sets additional electrons in motion. An applied voltage on the order of an AA battery also contributes.
This is new—Thermal energy normally plays a rather subordinate role in photocatalysts. However, because of the special coupling of MXene and gold, thermal energy is responsible for 57% of the reactivity in this case.
Successful tests
Alexander Genest from TU Wien carried out computer simulations that can be used to explain the effect of this electron transport. "Nitrate molecules are polarized directly on the gold nanoparticles," he says. "And this is exactly what makes the production of ammonia much easier. The amount of energy required for this is thus significantly reduced."
"Our MXene-gold catalyst achieved ammonia production of 2.1 mol per gram of catalyst per hour—this is a very high value that promises great potential for industrial applications," Rupprechter says.
Publication details
Yueru Ma et al, Thermoelectrics‐Mediated Photon‐Phonon‐Electron Coupling Enables Unconventional Thermal Contributions in Plasmonic Catalysis, Advanced Functional Materials (2026). DOI: 10.1002/adfm.77363
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Citation: Gold-MXene catalyst converts nitrate to ammonia using sunlight and 1.5 volts (2026, July 29) retrieved 29 July 2026 from https://phys.org/news/2026-07-gold-mxene-catalyst-nitrate-ammonia.html
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