Role of morphology in improving the catalytic performance of ZnCo2O4 for soot oxidation

Abstract

The extent of interaction between carbon and catalyst profoundly shapes soot oxidation results. The catalyst configuration notably influences the frequency of contact points in solid–solid interactions. This investigation studies the impact of three distinct ZnCo2O4 catalyst morphologies and their redox property on soot oxidation. The formation of the cubic phase of ZnCo2O4 via three distinct methods was revealed during XRD analysis. SEM analysis unveiled varying morphologies, including rod-shaped, rose petal-shaped, and bead-like structures. Notably, ZnCo2O4 exhibiting bead-like morphology demonstrated heightened levels of chemisorbed oxygen species which was observed during XPS analysis. The presence of Co2+ and Co3+ occupied at octahedral site ZnCo2O4 acted as the active sites for soot oxidation. With continuous redox property (Co 3+ → Co 2+) leading to the generation of active oxygen species and with an added advantage of surface morphology, the M2 sample (with bead-like morphology) exhibited superior soot oxidation activity, which is evident by its T50% value of 402 °C. This study underscores the essential role of catalyst morphology in influencing soot oxidation activity. Through a comprehensive array of structural, morphological, and catalytic analyses, this work sheds light on the correlation between catalyst architecture and enhanced soot oxidation performance.