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

To establish a permanent settlement on the Moon, it is essential to find solutions for producing oxygen (O 2 ) and water (H 2 O). One promising method is the in-situ production of H 2 O through the thermal reduction of lunar regolith containing iron oxide (Fe 2 O 3 ). This study explores the use of Electron Cyclotron Wave Resonance (ECWR) plasma for reducing Fe 2 O 3 , comparing its energy efficiency to traditional hydrogen (H 2 ) thermal reduction. Experiments were conducted using an H 2 /Ar plasma mixture on Fe 2 O 3 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 minutes of treatment. An intermediate Fe 3 O 4 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 H 2 /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. • Novel ECWR plasma method enables low‐temperature reduction of Fe 2 O 3 thin films. • Sequential reduction mechanism forms distinct layers of Fe, Fe 3 O 4 , and residual Fe 2 O 3 . • Controlled substrate heating accelerates reduction and improves microstructural uniformity. • Plasma-assisted reduction is up to six times more energy efficient than thermal processes.