Pt/doped mullite catalysts with abundant oxygen vacancies and enhanced oxygen migration capacity for NO oxidation

Unidirectional Electron Transfer on Bismuth-Doped Pt/YMn2O5 for Efficient CO Oxidation as Diesel Oxidation Catalysts

“…Notably, based on the high-resolution transmission electron microscopy (HRTEM) of Figures 3b and S9, it can be recognized that all catalysts have significant Pt/mullite interfaces, and the NO oxidation reaction by the participation of the interfacial oxygen vacancies (O v ) is the key factor for the catalysts to possess hydrothermal stability, which is in line with the previous work. 23,24 In addition, the corresponding EDS results for the catalysts doped with bismuth elements also showed that there is a high degree of consistency in the spatial distribution of Pt and bismuth elements and no significant segregation phenomenon or obvious core−shell structure is observed. 36 This is sufficient to suggest that there is some interaction between the Pt and bismuth elements.…”

“…As can be seen from Figure 5a, the desorption temperature of the catalyst is divided into three main temperature bands: The first temperature band is 50− 200 °C, where the desorption of oxygen species is attributed to the temperature range of reaction with CO; the second band is 200−300 °C, where the desorption of oxygen species is attributed to the temperature range of reaction with HC; and the third band is located in the high-temperature zone of 300− 500 °C where the desorption of oxygen species is attributed to the temperature range of reaction with NO. 24 Comparing the O 2 -TPD results in Figure 5a for the CO oxidation temperature interval from 50 to 200 °C, the Bi 3+ -doped catalysts had lower oxygen species desorption temperatures, corresponding to faster oxygen species migration, as well as low-temperature desorption of oxygen that is more readily involved in the oxidation of CO. In order to illustrate the oxygen migration rate more intuitively, the initial oxygen migration rate versus temperature is obtained after processing the curve (Figure 5b).…”

“…It is noteworthy that even after hydrothermal aging, the maximum NO conversion of all YMO mullite-containing catalysts reached about 40%, suggesting that the mullite-added catalysts have excellent hydrothermal stability, a finding that is consistent with previous work. 23,24 Besides, the T 30 for the oxidation of NO was 25 °C lower for the Bi 3+ -doped catalysts compared to the Bi 3+ -free catalysts. Further, based on the DOCs activities of catalysts doped with different bismuth contents shown in Figure S3, the optimal Bi doping was screened.…”

Nanoporous CeO2-Decorated Cu-SmMn2O5 Composite Mullite Oxide Catalyst for Toluene Oxidation

“…These oxygen vacancies are conducive to the gaseous oxygen activation to form adsorbed oxygen species and promote the oxygen mobility contributing to the enhanced toluene oxidation activity. 15,23 Moreover, Figure 7b shows that the temperature range of desorption peaks in the SCMO-Cu-IE sample is obviously lower than those of SCMO-Cu-HT and SCMO-Cu-EGM samples, implying that the SCMO-Cu-IE sample exhibits the best oxygen activity and oxygen mobility. Specifically, the desorption peak of surface lattice oxygen species in the SCMO-Cu-HT sample is obviously higher than those of other composite mullite oxides, being indicative of poor oxygen species activity.…”

“…At the current stage, introducing oxygen vacancies into the crystal structure of mullite oxide serves as an efficient way to solve the above-mentioned problem. − Researchers have developed various strategies to create oxygen vacancies including elemental doping − and interfacial decoration. ,, For example, Shen et al reported that Cu ions were doped into the crystal lattice of SmMn 2 O 5 replacing Mn 3+ ions to form the Cu 2+ –O–Mn 4+ structure . This Cu doping with inequivalence successfully created a large number of oxygen vacancies and weakened the strength of the Mn–O bond, thus enhancing the redox ability to convert lattice oxygen into active oxygen species.…”