Highly efficient production of nitrite and nitrate from air at the gas-water interface of nanobubbles.

Bose, Sandeep; Bahadorikhalili, Saeed; He, Yuanyi; Samouei, Hamidreza; Zare, Richard N · Sci Adv · 2026

basic_science · Level V

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Abstract

We report a simple, one-step conversion of air to nitrogen oxyanions (NO<i><sub>x</sub></i><sup>-</sup>), i.e., nitrate (NO<sub>3</sub><sup>-</sup>) and nitrite (NO<sub>2</sub><sup>-</sup>), at the gas-water interface (GWI) of nanobubbles (NBs). The nanobubble generator is placed inside an aqueous solution of 50 μM Fe<sup>2+</sup> to enhance the production of hydroxyl radicals (OH•) by initiating Fenton's reaction at the GWI. The formation of NO<i><sub>x</sub></i><sup>-</sup> does not require any external potential or radiation. The NO<i><sub>x</sub></i><sup>-</sup> production rate using NBs is found to be 60.4 ± 1.21 μM hour<sup>-1</sup>, which shows a fourfold increase in the production as compared to the same reaction performed in microbubbles (15 μM hour<sup>-1</sup>), which is the result from an enhanced electric field strength at the GWI. We propose that this nitrogen-fixation approach presents a promising pathway for an eco-friendly, energy-efficient, and scalable solution for NO<i><sub>x</sub></i><sup>-</sup>-based sustainable fertilizer production.