Facile synthesis of high-surface area platinum-doped ceria for low temperature CO oxidation

Abstract

Using a simple slow decomposition method of nitrate precursors, high-surface area platinumdoped ceria with a crystallite size of 9 nm can be prepared. The catalytic performance of the compound can be tuned by changing the reduction temperature under hydrogen (300°C, 500°C and 700°C). The catalyst treated at 300°C shows the best catalytic performance, being active at room temperature. The materials were analysed using a combination of structural characterization methods (X-ray diffraction (XRD), nitrogen physisorption, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM)), surface sensitive methods (X-ray photoelectron spectroscopy (XPS), H 2-chemisorption and H 2temperature-programmed reduction (TPR)) and X-ray absorption fluorescence spectroscopy (XAFS). HAADF-STEM and XAFS analysis suggests successful doping of platinum in the ceria lattice. After pretreatment at 300°C, the situation is slightly different. While no defined platinum nanoparticles can be identified on the surface, some platinum is in a reduced state (XPS, H 2-chemisorption).

Cerium(III) Nitrate Derived CeO2 Support Stabilising PtOx Active Species for Room Temperature CO Oxidation

“…Monitoring of the reaction under isothermal conditions (Figure S4) shows that the initial performance of the “PtO x /CeO 2 ‐220” catalyst at 25 °C (about 30 %) slowly decreases while at 180 °C CO conversion remain at the 100 % level at least during 2 h. The deactivation of the catalyst in CO oxidation at low temperatures can be attributed to the inhibition of platinum centres by strongly binding CO molecules. The analogous tendency was also recently found for Pt/CeO 2 catalysts prepared from ceria and platinum nitrates …”

“…(2006) the distance 3.01 Å was assigned to Pt−O−Ce, while 3.10 Å interaction was attributed to the Pt−O−Pt distance. Gatla et al . reported distances of 3.10 and 3.16 Å for Pt−O−Pt and Pt−O−Ce moieties in the Pt/CeO 2 catalysts, respectively.…”

“…The scalable methods of preparation of CeO 2 supports vary from the cerium salts solution hydrolysis to the flame spray pyrolysis . Among these methods the simplest and most straightforward one is the thermal decomposition of cerium salts, such as Ce(NO 3 ) 3 ⋅ 6H 2 O, Ce 2 (C 2 O 4 ) 3 , (NH 4 ) 2 [Ce(NO 3 ) 6 ], and Ce 2 (CO 3 ) 2 O ⋅ H 2 O . Despite its apparent simplicity, a variety of parameters including composition of the precursor, temperature, ramping rate, gaseous atmosphere, and precursor pre‐treatment, can be used to control the key characteristics of the resulting ceria materials.…”

“…[1,2] Particularly, catalysts containing platinum deposited on ceria were found to provide an excellent CO conversion at moderate temperatures, keeping their activity after hightemperature stresses. [3][4][5][6][7][8][9][10] The PtÀ Ceria interaction lowers the reaction ignition temperature, which is crucial for preventing air pollution when an engine starts or for autonomous air cleaning systems.…”

“…[7,17] Among these methods the simplest and most straightforward one is the thermal decomposition of cerium salts, such as Ce (NO 3 ) 3 6 ], and Ce 2 (CO 3 ) 2 O · H 2 O. [8,[18][19][20] Despite its apparent simplicity, a variety of parameters including composition of the precursor, temperature, ramping rate, gaseous atmosphere, and precursor pretreatment, can be used to control the key characteristics of the resulting ceria materials.…”