Abstract: The synthesis of nanocrystalline mesoporous MgO with a high surface area and controlled morphology is crucial for applications in energy storage, adsorption, and catalysis. This study introduces an innovative, template-free, one-step synthesis method for mesoporous MgO utilizing gliding arc plasma (GAP) technology, enabling rapid production within milliseconds. The crystallinity and grain size of the sample may be easily modulated by adjusting the experimental settings. Characterization revealed typical mesoporous features across all samples, as evidenced by Type IV isotherms and H3-type hysteresis loops. The specific surface area and pore volume can be tailored over a broad range, from 19 m²/g to 140 m²/g and 0.09 cm³/g to 0.629 cm³/g, respectively. Modifications to plasma parameters and precursor conditions facilitated changes in MgO morphology and particle size regulation. Surface elemental composition and chemical state analyses confirmed the formation of pure-phase MgO, ensuring high material purity. Photocatalytic degradation experiments highlighted the superior photocatalytic activity of the synthesized MgO, exhibiting a degradation rate constant of 0.008 min^-1. Ultimately, this work establishes a critical relationship between the synthesis conditions and the resulting properties of magnesium oxide, elucidating the underlying mechanisms of GAP-assisted one-step synthesis method for producing mesoporous nanocrystalline MgO. The controllable, rapid, and template-free nature of the GAP method represents a significant advancement in materials science, offering a powerful route for tailoring nanostructured materials for specific technological applications.

Key words: Nanocrystalline MgO, Mesoporous materials, Template-free synthesis, One-step process, Non-thermal plasma