Balancing acid and redox sites of phosphorylated CeO2 catalysts for NOx reduction: The promoting and inhibiting mechanism of phosphorus

Revealing the Dynamic Behavior of Active Sites on Acid-Functionalized CeO2 Catalysts for NOx Reduction

“…As for the CeO 2 -W-H catalyst, the amount of weak acid sites did not change much while the medium strong acid sites decreased significantly, indicating that the medium strong acid sites played a key role in the SCR activity compared to the weak acid sites. 24 A similar phenomenon has been demonstrated in other previous SCR catalysts. 19,38 The acid amounts of the sulfated CeO 2 catalyst were also investigated.…”

“…It was shown that plenty of inert nitrate species were accumulated upon the CeO 2 surface. 24 As for CeO 2 -W-M and CeO 2 -W-H catalysts, the band intensity of adsorbed NO x species decreased. When the temperature reached 300 °C upon the CeO 2 -W-M catalyst, the adsorbed nitrate species were desorbed completely, indicating that a great number of reactive NO x species can react more readily with NH 3 (Figure S19).…”

“…The adsorption of NH 3 upon CeO 2 revealed a large number of adsorbed NH 3 species on Lewis acid sites located at 1311, 1246, 1162, and 1065 cm −1 (Figure 8). 21,24 After NO + O 2 were introduced for 15 min, the adsorbed NH 3 species disappeared rapidly and the adsorbed NO x species corresponding to bridged nitrate (1618 cm −1 ), monodentate nitrate (1345 cm −1 ), and monodentate nitrite species (1197, 1091, and 1065 cm −1 ) started to appear. 19 For the CeO 2 -W-L catalyst, after the adsorption of NH 3 , the NH 4 + (1432 cm −1 ) and a large number of NH 3 species (1573, 1374, 1131, and 1030 cm −1 ) emerged.…”

“…22 Peng et al demonstrated that the coordination unsaturated W n+ cations in crystalline WO 3 provided Lewis acid sites and the W−O−W or W�O modes in Ce 2 (WO 4 ) 3 increased the number of Brønsted acid sites. 23 Although some studies have promulgated the strong interaction between CeO 2 and modification species on their quantitative relationship among activity and redox/acid sites, 24,25 the issue on how the active sites of non-V 2 O 5based metal oxide catalysts affect the catalytic activity from the dynamics of the reaction process has still not been systematically explored. Herein, WO 3 and SO 4 2− are used as the specific promoters to regulate acidity and the redox property of CeO 2 .…”

CeO2/CuO/NiO hybrid nanostructures loaded on N-doped reduced graphene oxide nanosheets as an efficient electrocatalyst for water oxidation and non-enzymatic glucose detection

“…1,2 CeO 2 , as an n-type semiconductor, can also interact with other materials and modify their electronic structure. 3 These properties make CeO 2 a good candidate for catalytic reactions, [4][5][6][7] sensors, [8][9][10] and biomedical applications. [11][12][13] However, the use of CeO 2 is limited due to its poor electrical conductivity and limited active sites.…”