# Improving Plasma‐Catalytic Ammonia Synthesis Using a Coaxial Double‐Helix‐Electrode Reactor

## TL;DR

A new reactor design improves ammonia production using plasma and catalysts under low-energy, eco-friendly conditions.

## Contribution

A coaxial double-helix-electrode reactor enhances plasma-catalytic ammonia synthesis through uniform discharge and electric-field engineering.

## Key findings

- The double-helix design generates a homogeneous electric field of ~7×10⁶ V m⁻¹, outperforming conventional DBD reactors.
- The reactor achieves an energy yield of 3.68 g NH₃ kWh⁻¹ when combined with a Ni/Al₂O₃ catalyst.
- Optimized electrode geometry increases electron density and plasma-catalyst synergy for higher ammonia production.

## Abstract

Developing energy‐efficient ammonia synthesis under mild and carbon‐neutral conditions remains a major challenge for sustainable nitrogen fixation. Here, we present a coaxial double‐helix‐electrode‐based double‐dielectric barrier discharge (DBD) reactor, termed a “double‐helix” design, featuring dual quartz barriers and symmetric high‐voltage and grounded electrodes to achieve uniform, high‐intensity volume discharge for plasma‐catalytic ammonia synthesis. Three‐dimensional electrostatic simulations demonstrate that this configuration generates a strongly coupled and spatially homogeneous electric field (∼7 × 106 V m−1), significantly outperforming conventional single‐dielectric DBD designs (∼1 × 106 V m−1). An optimized Ni electrode with a 1 mm winding pitch increases electron density, as evidenced by optical emission spectroscopy (OES, I
N2+(425 nm)/I
N2*(335 nm) = 0.15). Under plasma‐only operation, the double‐helix DBD reactor produces approximately 2.5‐fold higher NH3 concentration than a conventional DBD at identical power input. When integrated with a Ni/Al2O3 catalyst, synergistic plasma‐catalyst interactions further enhance ammonia yield and energy efficiency, achieving an energy yield of up to 3.68 g NH3 kWh−1 under 5.92 W discharge. Comprehensive analysis combining electric‐field simulations, transient discharge imaging, and catalytic performance measurements elucidates the intrinsic coupling between electrode architecture, discharge physics, and catalytic function. This work demonstrates that electric‐field engineering is an effective strategy for enabling stable volume discharge and enhancing plasma‐catalytic ammonia synthesis, offering a generic design principle for next‐generation low‐carbon nitrogen‐fixation systems.

A symmetric double‐dielectric, double‐helix dielectric barrier discharge (DBD) reactor enables uniform volume discharge, enhanced energetic electrons, and strong plasma‐catalyst synergy, delivering high‐efficiency ammonia synthesis under mild, low‐carbon conditions.© 2026 WILEY‐VCH GmbH