Fig. 1: Thermogravimetric analysis curves of Co3O4 microparticles and nanoparticles during one and five thermal redox cycles; blue lines represent normalized weight (the difference between theoretical and actual weight loss, divided by theoretical weight loss, for a complete Co3O4-to-CoO conversion), black lines indicate the temperature profile, and red lines show the derivative of mass change (DTG).

(A, B) normalized weight of microparticles (A) and nanoparticles (B) during one redox cycle (900–850–800–900 °C); (C, D) normalized weight and DTG curves of microparticles (C) and nanoparticles (D) over five redox cycles (900–800 °C) with 30 min holding time at each temperature. Source data are provided as a Source Data file.