Document Type

Article

Publication Date

2026

Publication Title

Pulsed Power

Volume

1

Issue

1

Pages

100005

DOI

10.1016/j.pup.2026.100005

Abstract

Developing energy-efficient technologies for carbon-neutral ammonia (NH₃) synthesis is critical for decentralized fertilizer production and global decarbonization. This study investigates generating NH₃ from water using a nanosecond pulsed atmospheric pressure plasma jet (ns‑APPJ) operating in either N₂ or dry air. The plasma jet reactor employed approximately 250 ns, up-to-22 kV pulses at 500 Hz to sustain a nonequilibrium discharge impinging directly on static liquid water. The kinetics, energy efficiency, and product selectivity of NH3 formation were quantified as functions of the pulse voltage, repetition frequency (PRF), and gas flow rate. NH₃ production increased linearly with treatment time and scaled strongly with pulse voltage, reaching a maximum of 0.0345 mg h⁻¹ at 22 kV. Even at higher voltages, the production of NH3 was more favorable than oxidative nitrogen species (i.e., NO₂- and NO₃-), with the NH₃ selectivity increasing from 25% at 17 kV to 85% at 22 kV. Reducing the PRF improved energy efficiency but decreased production rates, while lower gas flow rates enhanced NH3 formation, suggesting increased residence time and improved plasma–liquid mass transport. Optical emission spectroscopy revealed dominant N2(C–B) emissions, confirming that electron impact excitation is important for NH₃ formation. Despite modest production rates relative to other plasma–liquid systems, the reactor operated on a low average power (< 3 W) and maintained liquid temperatures below 41 °C, demonstrating a strongly nonthermal process. This work established a baseline for ns‑APPJ‑driven NH₃ synthesis and identified the key operating parameters for optimizing the reaction efficiency. The findings highlight the potential of nanosecond pulsed plasma strategies for localized, low‑carbon NH₃ production and encourage designing reactors that incorporate flowing liquid architectures to enhance the yield.

Rights

© 2026 The Authors.

This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License.

Original Publication Citation

Caudell, Z., Rich, L., Pakhomova, O., & Jiang, C. (2026). Ammonia synthesis by nanosecond pulsed atmospheric pressure plasma jets impinging on water. Pulsed Power, 1(1), Article 100005. https://doi.org/10.1016/j.pup.2026.100005

ORCID

0000-0003-4950-4130 (Pakhomova), 0000-0001-8895-2580 (Jiang)

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