FexC enhancing the catalytic activity of FeNx in oxidative dehydration of N-heterocycles

To enhance the catalytic activity by designing metal particles combined with atomically dispersed non-noble metal catalyst is a huge challenge,which yet has not been studied widely in organic reactions.Herein,we describe a simple and efficient method to synthesize FexC combined with Fe single atoms anchored on the Ndoped porous carbon by regulating pyrolysis temperature.Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)and extended X-ray absorption fine structure(EXAFS)spectroscopy corroborate the existence of atomically dispersed Fe and the coordination number between Fe and N atoms.The Fe-N-C-800 catalyst exhibits the highest catalytic activity giving the 97%yield of quinoline in dehydration of 1,2,3,4-tetrahydroquinoline(THQ)reaction at a mild condition(60C,O_(2)balloon),and it shows good stability with 80%isolated yield after five consecutive dehydration reactions.Moreover,density functional theory(DFT)calculations reveal that coexistence of Fe_(x)C and FeN_(x)structure exhibits high activity owing to the lowest adsorption energy of co-adsorbed O_(2)and THQ and the longest N-H bond length of THQ,that is because the existence of FexC induces the charges transfer.Our work may open a new route to design metal particles combined with atomically dispersed non-noble metal catalysts with high activity in organic synthesis.