Flash Joule-heating synthesis of MoO₂ nanocatalysts in graphene aerogel for deep catalytic oxidative desulfurization

Ultra-high-temperature flash Joule-heating of organometallic precursor-embedded reduced graphene oxide (rGO) aerogel represents a highly efficient approach for the ultrafast production of nanocatalysts, while such a methodology has been scarcely applied to 3D nanocarbon-based aerogel monoliths. Herein, we demonstrate the rapid synthesis of MoO2 nanoparticles within the aerogel matrix via a 1-s high-temperature flash Joule-heating process (~1700°C), resulting in the formation of the hybrid MoO₂@rGO aerogel with uniformly distributed nanoparticles. Nitrogen adsorption/desorption analysis indicates discernible internal microstructural disparities attributed to the additional 1-s flash-heating and the substantial generation of MoO2 nanoparticles. This aerogel exhibits exceptional catalytic functionality, achieving up to 99.8% efficiency in converting dibenzothiophene to dibenzothiophene sulfone. Density functional theory calculations provide insights into the catalytic mechanism, revealing that the Mo center shows accumulated electron density contributed from the electron-rich graphene substrate. This electron density enhancement significantly enhances the catalytic activity, enabling deep desulfurization. The proposed flash nanocatalyst synthesis approach presented here can be extended to fabricate multimetallic nanocatalysts and high-entropy alloys within the cylindrical aerogel entity, exhibiting great potential for applications in industry-relevant flow chemistry, electrochemistry, industrial catalysis, and beyond.