Structural and phonon modulation in cinnamon-fueled MnV2O6 nanoparticles for high-efficiency photocatalysis

MnV2O6 nanoparticles were synthesized using cinnamon powder as a natural biofuel through a green combustion route. This represents a friendlier and cost-effective methodology for the fabrication of metal vanadates. The catalyst showed 81.96% methylene blue degradation in 180 min under visible light, and its performances were affected by the dosage of the catalyst, the concentration of the dye, pH, and reactive oxygen species. A kinetic study supported the pseudo-first-order model, and scavenger studies evidenced that •OH and O2•- radicals are predominant. Comprehensive characterizations with the help of XRD, SEM, FTIR, UV-Vis, XPS, TEM, TGA, and BET revealed the monoclinic phase, morphology, functional groups, optical features, surface composition, thermal stability, particle characteristics, and surface area. DFT calculations supported an indirect band gap of 1.71 eV, and this calculated value is well matched with the experimental value of 1.64 eV. DOS/phonon analyses revealed Mn 3d/O 2p → V 3d transitions and further lattice vibrational effects, which enhanced the charge mobility of the photocatalyst. Thus, the present study demonstrates a novel integration of green synthesis-DFT and establishes cinnamon-mediated MnV2O6 as a potential sustainable photocatalyst for environmental remediation. GRAPHICAL ABSTRACT