Vijay, M.P.A.Patil, S.S.Madhura, D.R.Anjana, A.P.Gouramma, P.Prasad Dasari, H.P.Arya, S.B.Harshini, H.2026-02-042022Materials Today: Proceedings, 2022, 57, , pp. 1865-1870https://doi.org/10.1016/j.matpr.2022.01.119https://idr.nitk.ac.in/handle/123456789/22730NiO sample is synthesized using the EDTA citrate complex method and calcined at 600 °C/5 h. Ni sample was acquired by reducing NiO to Ni at 600 °C in 4% H<inf>2</inf>/N<inf>2</inf> atmosphere. Its physicochemical properties were obtained by XRD and Raman spectroscopy analysis, where it confirmed the complete reduction of NiO to Ni. SEM and TEM micrographs revealed a drastic particle growth for the Ni, indicating NiO sintering during the reduction process and a considerable surface morphology change. Ozawa and KAS methods were used to calculate the mean activation energy (E<inf>a</inf>) value. NiO displayed lower E<inf>a</inf> than Ni. Hence, NiO showed better catalytic activity than Ni. © 2022Activation energyCatalyst activityDiesel enginesMorphologyNanoparticlesOxidationPhysicochemical propertiesSinteringSootSurface morphologyTransmission electron microscopyX ray powder diffractionCitrate complexComplex methodsDiesel soot oxidationEthylene diamine tetra-acetic acidEthylenediamine tetra acetic acid-citrate complex methodNanoparti-clesOxidation activitiesOxidation statePhysicochemical propertySynthesisedNickel oxide