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.　©　2024　American　Institute　of　Chemical　Engineers.