Reduction of iron oxide (alpha-Fe2O3) with a hydrogen rich plasma produced by an Electron Cyclotron Wave Resonance source

Authors

Sikirić M., Choquet P., Philippe A.M., Valle N., Hadler K., Bjelajac A., Chemin J.B., Kadok J., Bulou S.

Reference

Vacuum, vol. 240, art. no. 114508, 2025

Description

To establish a permanent settlement on the Moon, it is essential to find solutions for producing oxygen (O₂) and water (H₂O). One promising method is the in-situ production of H₂O through the thermal reduction of lunar regolith containing iron oxide (Fe₂O₃). This study explores the use of Electron Cyclotron Wave Resonance (ECWR) plasma for reducing Fe₂O₃, comparing its energy efficiency to traditional hydrogen (H₂) thermal reduction. Experiments were conducted using an H₂/Ar plasma mixture on Fe₂O₃ thin films at varying substrate temperatures and treatment times. Characterization techniques revealed a multilayer structure forming during the reduction, with a rapid transition to metallic iron (Fe) on the surface after 15 min of treatment. An intermediate Fe₃O₄ layer developed with extended reduction time, resulting in a distinct three-layered structure. Controlled heating above 200 °C significantly accelerated the reduction process while maintaining the same mechanism. Energy efficiency calculations indicate that H₂/Ar ECWR plasma can be up to six times more efficient than simple thermal reduction, highlighting its potential as an effective method for lunar oxygen production.

Link

doi:10.1016/j.vacuum.2025.114508