Molten oxide electrolysis for lunar oxygen generation using in-situ resources

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Molten oxide electrolysis for lunar oxygen generation using in-situ resources

Vai, A.T. / Yurko, J.A. / Wang, D.H. / Sadoway, D.R.

Molten Oxide Electrolysis (MOE) is a promising and laboratory-proven in-situ resource utilization technology for generating oxygen from lunar regolith simulant. Prior to this work, iridium metal was the only demonstrated suitable inert anode material, but its use had been limited to laboratory-scale testing owing to its extraordinarily high density, hardness, and cost. In the current work, electrodes fabricated from 50:50 (wt%) iridium-tungsten alloy were shown to be functional inert anodes for molten oxide electrolysis. The performance of the iridium-tungsten alloy was compared with that of pure iridium in a series of constant current electrolysis experiments under a variety of conditions, including the use of different electrolytes, cathodes, currents, and experiment durations. The iridium-tungsten alloy was also examined post-run by scanning electron microscopy and electron dispersive spectroscopy to determine its durability in the electrolyte, and to perform a preliminary survey of the nature of diffusion in Ir-M systems in support of potential development of Ir-based anode systems. In the specific case of Ir-W, it was demonstrated that while the bulk material is substantially stable over the time scales accessed (<6 h), a diffusion barrier will almost certainly required to ensure the long-term performance of any anode system using Ir-M interfaces.