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Item Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Geethu, J.; P, M.R.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Bhaskar Babu, G.U.Binary metal oxides of CeO2-Sm2O3 (CSx, x varies from 10 to 90 mol%) along with pure CeO2 and Sm2O3 were synthesised successfully by the EDTA-Citrate method. From XRD, Raman spectroscopy and UV–vis DRS results, the whole composition of metal oxides exist in three phases: (fluorite phase (F) (CS10-CS30), bi-phase (fluorite (F) + cubic (C)) (CS30-CS90) and cubic phase (C) (Sm2O3)). For CSx samples, the calculated band gap energy values obtained from the UV–vis DRS results were in between 3.0–5.1 eV and fluorite phase samples (CS10–CS30) displayed lower band gap energy values (3.04–3.07 eV) than compared to the samples in other phases. Similarly, from XPS analysis, fluorite phase samples (CS10–CS30) showed higher surface oxygen vacancy concentration than compared to samples in other phases. Catalytic activity for soot oxidation is carried out on CSx samples, and the T50 temperature is in between 480–540 °C. Fluorite phase samples (CS10 CS30) showed higher surface area, lower degree of agglomeration, lower band gap energy, higher oxygen vacancy concentration and better catalytic activity for soot oxidation. Among all the CSx samples, CS10 sample displayed highest surface area (38 m2/g), lowest degree of agglomeration (0.36), lowest band gap energy (3.04 eV), highest oxygen vacancy concentration (64%) and highest soot oxidation activity (T50 = 480 °C). The order of the soot oxidation activity of CSx samples followed the same trend of band gap energy values. © 2018 Elsevier B.V.Item Surface morphology and phase stability effect of Ceria-Hafnia (CHx) binary metal oxides on soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.CeO2-HfO2 (CHx) binary metal oxides over whole composition range (0–100%) are synthesised using the EDTA-Citrate method and calcined at 600 °C/5 h. From XRD analysis, the sample series are classified as fluorite (F) phase for CH10-CH30, hybrid (F + M) phase for CH40-CH90 and monoclinic (M) phase for CH100 sample, respectively and the results were further confirmed using Raman spectroscopy. From SEM analysis, a clear surface morphology change is noticed for fluorite, hybrid and monoclinic phases of the CHx binary metal oxides. Further, Selected Area Electron Diffraction (SAED) analysis also confirmed the single and hybrid phases of CHx binary metal oxides. The soot oxidation for the CHx binary metal oxides displayed high catalytic activity for Fluorite phase (CH10 ? CH30) samples and a decrease in catalytic activity is noticed for the Hybrid phase (CH40 ? CH90) samples. The change in catalytic activity coincides with the change in the surface morphology and phase change for the CHx binary metal oxides. Among the Fluorite phase samples, CH10 sample displayed the highest catalytic activity (T50 = 430 °C) with higher surface area (29 m2/g), lower particle size (26 nm), lower degree of agglomeration (? = 2.8) higher surface oxygen concentration (44%). Isothermal-Time-on-stream (ITOS) analysis also showed that the CH10 sample can achieve T50 in a shorter time than compared to other CHx binary metal oxides. Surface morphology and phase stability can also play as key descriptors in screening CHx binary metal oxides for soot oxidation activity. © 2018 Elsevier B.V.Item Effect of ionic radius on soot oxidation activity for ceria-based binary metal oxides(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2019) Anjana, A.P.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.CeO2 (C) along with binary metal oxides of Ce0.9M0.1O2-? (M = Sn, Hf, Zr, Gd, Sm, and La; CT, CH, CZ CG, CS, and CL) are synthesized using the EDTA–citrate method. Samples having an ionic radius smaller (CT, CH, and CZ) and larger (CG, CS, and CL) than Ce4+ are classified separately, and their soot oxidation activity is analyzed. The incorporation of dopant is confirmed from lattice constant variation in X-ray diffraction result. The critical descriptors for the activity are dopant nature (ionic radius and oxidation-state), single-phase solid solution, lattice strain, reactive (200) and (220) planes, Raman intensity ration (Iov/IF2g), optical bandgap, reducibility ratio, and surface oxygen vacancy. Smaller ionic radius, isovalent dopants (CH and CZ) create a defect site by lowering the optical bandgap along with improved surface oxygen vacancy concentration and thus enhanced soot oxidation activity. Aliovalent dopant with larger ionic radius shows the involvement of lattice oxygen in oxidation reaction by charge compensation mechanism. CL showed the highest activity amongst larger ionic radius samples. © 2019 Curtin University and John Wiley & Sons, Ltd.