Microspherical core-shell MoO2-graphitic C3N4 heterojunction promoted integration leading to Krohnke pyridines and degradation of xylenol orange

In the current study, we fabricated a microspherical core-shell consisting of MoO2 and graphitic-C3N4 by a simple one-step calcination procedure. TEM analysis revealed MoO2 at the core (average diameter of 210 nm), surrounded by a graphitic-C3N4 shell. MoO2 of the core exhibited monoclinic symmetry. The Raman spectrum additionally confirmed the monoclinic MoO2. The sample was EPR active, indicating paramagnetic oxygen vacancies. It contained meso-sized pores and a high surface area. The core-shell's optical bandgap was higher than the pure metallic MoO2. XPS results confirmed the existence of molybdenum in IV and VI oxidation states. The core-shell's heterojunction catalyzed the degradation of xylenol orange (XO) dye into C8H9ONH3+, C6H5SO3- and C15H14ONH3+SO3-. The core-shell promoted the efficient synthesis of symmetrical and unsymmetrical 2, 4, 6-triaryl pyridines through the oxidative condensation of acetophenones with benzylamines in good to excellent yields using molecular oxygen as the oxidant. The catalyst is recyclable for both these reactions.

Automated summary

This study successfully fabricated a microspherical core-shell structure consisting of MoO2 and graphitic-C3N4 through a simple one-step calcination procedure. The core-shell exhibited high optical bandgap, facilitated dye degradation, and promoted organic synthesis.