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Abstract

Water is crucial in space missions, and developing lightweight, high-performing catalysts for water recycling is essential. Extensive research on nanosized and even single-atom catalysts supported on oxides has been conducted for this purpose. However, the oxide supports usually constitute over 90% of the total mass, so the catalysts are heavy. Here, we fabricated a light, fibrous RuO₂ nanostructured textile consisting solely of RuO₂ nanoparticles (NPs), which did not require an oxide support, and evaluated it in the Sabatier reaction for water recycling. Remarkably, this support-free catalyst textile displayed an unprecedented catalytic mass activity (~60 mmol_CH4 h^-1 g_cat^-1 at 160 °C), which was approximately 20 times higher than that of a previously reported Ru/TiO₂ catalyst, and the highest TOF (0.021 s^-1 at 160 °C). Although well-known catalyst degradation was observed during prolonged testing, the performance of the textile remained exceptional even after 46 hours of continuous operation. A detailed surface analysis unveiled phenomena such as RuO₂ reduction, nanoparticle growth, surface smoothing, and Ru loss during the reaction, contributing to degradation. We expect that addressing these intrinsic and thermodynamically driven phenomena will improve activity and durability.