A sunlight-and-battery catalyst turns nitrate into ammonia in the lab

Researchers report a gold-MXene catalyst that makes ammonia from nitrate using sunlight and about 1.5 volts.

Researchers at TU Wien in Austria and Soochow University in China have built a catalyst that converts nitrate into ammonia using sunlight plus a voltage of roughly 1.5 volts \u2014 the level of an AA battery. The catalyst pairs MXene, a material made mainly of carbon and titanium arranged in atomically thin layers, with gold nanoparticles. The layers act as light-capturing nanoantennas; when sunlight strikes them, electrons oscillate in collective motions called plasmons, delivering energy to the gold surface where the ammonia-forming reaction occurs. The team reports that thermal energy accounts for 57% of the reactivity, and that the catalyst produced 2.1 moles of ammonia per gram per hour. The work appeared in Advanced Functional Materials.

The mechanism matters because ammonia is the backbone of nitrogen fertilizer, and its conventional production is highly energy-intensive. A route driven largely by sunlight and a small voltage \u2014 and able to draw its nitrate from wastewater \u2014 points at cheaper fertilizer and a use for a common pollutant.

Cheaper, less energy-hungry ammonia flows straight through to the cost of food, since fertilizer is one of the largest input costs in modern agriculture. Turning wastewater nitrate into a feedstock would also gate a pollution problem rather than create one.

The honest limit: this is a laboratory catalyst, and industrial application is described as potential, not achieved. The findings rest on a single peer-reviewed study reported through a university press release. Watch for scale-up results and whether the production rate holds outside the lab.

Source: Phys.org