Property and Reactivity Relationships of Co₃O₄ with Diverse Nanostructures for Soot Oxidation

Abstract

Cobalt oxide (Co3O4) nanostructures with different morphologies (nanocubes, nanoplates, and nanoflowers) were synthesized by a simple hydrothermal method and used for catalytic oxidation of soot particles. Through the study of the physicochemical properties of the catalysts, the key factors affecting the performance of soot oxidation were investigated. The results showed that all three kinds of Co3O4 nanocrystals exhibited excellent low-temperature activity in catalytic oxidation of soot, and the Co3O4 nanoflowers showed higher oxidation activity of soot compared with Co3O4 nanocubes and Co3O4 nanoplates, whose T m was only 370 °C. The excellent activity of Co3O4 nanoflowers was due to the large amount of Co3+ and lattice oxygen on their surface and highly defective structure, which promoted the adsorption and activation of oxygen species. The large crystallite size and few surface defects were the main reasons for the poor catalytic performance of Co3O4 nanocubes. During soot oxidation, the crystallite size of the catalysts and the contact between the catalysts and soot played a significant role in the catalytic performance.

Recent Advances in Co3O4-Based Composites: Synthesis and Application in Combustion of Methane

“…Interestingly, the methane conversion rate declined with increasing temperature, whereas it rose with decreasing temperature (300~400 • C) under the auspices of the Au-Pd-3.61CoO/3DOM Co 3 O 4 catalyst. Furthermore, the researchers observed that the deactivation of 3DOM Co In conclusion, doping of noble metals can enhance the oxygen activity and stabili of Co-O bond and affect the fracture and formation of Co-O bond, thus raising the con centration of oxygen vacancies [102][103][104]. For instance, doping noble metals such as Pt an Pd can effectively introduce numerous oxygen vacancies while also boosting the Cobond content on composite catalyst material surfaces.…”

“…After Co loading, the methane combustion catalytic activity was significantly boosted, and SmMn2O5 proved to be the key player in stabilizing the Co3O4 against sintering. This kind of mutual promotion paid off, with the Co/SMO-50% (50% represents the proportion of SmMn2O5) catalyst displaying overall superior catalytic performance with In conclusion, the appropriate amount of metal oxide doping can enhance the oxygen activity and stability of Co-O bond and elevate the concentration of active oxygen [132][133][134][135], thus improving the catalytic efficiency of methane oxidation reaction [102,[136][137][138]. For example, doping of CeO 2 can introduce a large number of oxygen vacancies into the Co In addition, ZrO 2 can also cause lattice distortion, increase surface defects, promote the formation of Co-O bonds, and improve its oxygen activity and stability.…”

“…In conclusion, doping of noble metals can enhance the oxygen activity and stability of Co–O bond and affect the fracture and formation of Co–O bond, thus raising the concentration of oxygen vacancies [ 102 , 103 , 104 ]. For instance, doping noble metals such as Pt and Pd can effectively introduce numerous oxygen vacancies while also boosting the Co–O bond content on composite catalyst material surfaces.…”

“…In conclusion, the appropriate amount of metal oxide doping can enhance the oxygen activity and stability of Co–O bond and elevate the concentration of active oxygen [ 132 , 133 , 134 , 135 ], thus improving the catalytic efficiency of methane oxidation reaction [ 102 , 136 , 137 , 138 ]. For example, doping of CeO 2 can introduce a large number of oxygen vacancies into the Co 3 O 4 lattice, forming more oxygen active sites on the Co–O bond, thereby increasing the oxygen reduction capacity of the Co 3 O 4 catalyst surface and the adsorption capacity of methane molecules.…”

Soot Erased: Catalysts and Their Mechanistic Chemistry

“…Moreover, innovative catalyst materials, such as transition metal oxides and non-noble metal catalysts, have shown promising results in catalyzing soot oxidation while addressing cost and sustainability concerns [68]. Similarly, nanostructured catalyst materials have emerged as a prominent trend in soot oxidation research [69]. Nanostructured catalysts exhibit increased surface area and enhanced catalytic activity, enabling more efficient soot oxidation at lower temperatures.…”