Designing CuO_x Nanoparticle-Decorated CeO₂ Nanocubes for Catalytic Soot Oxidation: Role of the Nanointerface in the Catalytic Performance of Heterostructured Nanomaterials

Abstract

This work investigates the structure-activity properties of CuOx-decorated CeO2 nanocubes with a meticulous scrutiny on the role of the CuOx/CeO2 nanointerface in the catalytic oxidation of diesel soot, a critical environmental problem all over the world. For this, a systematic characterization of the materials has been undertaken using transmission electron microscopy (TEM), transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDS), high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM), scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS), X-ray diffraction (XRD), Raman, N2 adsorption-desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The TEM images show the formation of nanosized CeO2 cubes (∼25 nm) and CuOx nanoparticles (∼8.5 nm). The TEM-EDS elemental mapping images reveal the uniform decoration of CuOx nanoparticles on CeO2 nanocubes. The XPS and Raman studies show that the decoration of CuOx on CeO2 nanocubes leads to improved structural defects, such as higher concentrations of Ce(3+) ions and abundant oxygen vacancies. It was found that CuOx-decorated CeO2 nanocubes efficiently catalyze soot oxidation at a much lower temperature (T50 = 646 K, temperature at which 50% soot conversion is achieved) compared to that of pristine CeO2 nanocubes (T50 = 725 K) under tight contact conditions. Similarly, a huge 91 K difference in the T50 values of CuOx/CeO2 (T50 = 744 K) and pristine CeO2 (T50 = 835 K) was found in the loose-contact soot oxidation studies. The superior catalytic performance of CuOx-decorated CeO2 nanocubes is mainly attributed to the improved redox efficiency of CeO2 at the nanointerface sites of CuOx-CeO2, as evidenced by Ce M5,4 EELS analysis, supported by XRD, Raman, and XPS studies, a clear proof for the role of nanointerfaces in the performance of heterostructured nanocatalysts.

Electrochemical Detection of As (III) on a Manganese Oxide‐Ceria (Mn2O3/CeO2) Nanocube Modified Au Electrode

“…CeO 2 particles are cubic with an average size of 22±5 nm. The d spacing of the lattice fringe was measured to be 0.271 nm, which corresponds to the fluorite structured CeO 2 (100) plane . Mn 2 O 3 nanoparticles with a size of 6±2 nm were mainly decorated on the edge of the CeO 2 nanocubes.…”

Fabrication of CeO2–MOx (M = Cu, Co, Ni) composite yolk–shell nanospheres with enhanced catalytic properties for CO oxidation

“…In the Cu 2p spectrum (Fig. 7), two pronounced peaks at about 932.6 and 952.3 eV can be attributed to Cu 2p 3/2 and Cu 2p 1/2 of Cu(I), respectively, whereas a broad shake-up peak observed at around 946 eV can be assigned to the presence of Cu(II) [33]. It is therefore clear that the CeO 2 –CuO x sample contains coexisting Cu + /Cu 2+ oxidation states.…”

“…For MO x -decorated CeO 2 nanostructures, the enhanced redox properties at the interface sites play a key role in the superior catalytic efficiency in the oxidation reaction [33]. The charge balance of redox couples of Cu 2+ /Cu + and Ce 4+ /Ce 3+ (Ce 3+ + Cu 2+ ↔ Ce 4+ + Cu + ) and the lowering of redox potentials of Cu species interacting with CeO 2 support could be responsible for the improved catalytic performance of the CeO 2 –CuO x catalyst [43].…”

Effect of Potassium Nitrate Modification on the Performance of Copper‐Manganese Oxide Catalyst for Enhanced Soot Combustion

“…[6] In particular, ac atalyzed diesel particlef ilter (CDPF), with catalyst coatedo nt he filter,h as been developed to eliminate the trapped sootc ontinuously to eliminate the drawbacks, such as high oil consumption, mechanical damage caused by overheating, andi ncreasing back pressure, that are usually found in an ordinaryD PF system. [13][14][15][16][17][18] Among these, supported noble-metal-based catalysts are the best candidates for sootc ombustion and show low values of the characteristic finishing temperature (T f ). [13][14][15][16][17][18] Among these, supported noble-metal-based catalysts are the best candidates for sootc ombustion and show low values of the characteristic finishing temperature (T f ).…”

“…[7] Various catalysts have been developed for soot combustion to date, for example, noble-metalbased catalysts, [8] transition metal (mixed) oxides, [9] perovskite and/or perovskite-like mixed oxides, [10] spinel mixed oxides, [11] alkali/alkaline earth metal compounds, [12] and the famousc eriabased oxides. [13][14][15][16][17][18] Among these, supported noble-metal-based catalysts are the best candidates for sootc ombustion and show low values of the characteristic finishing temperature (T f ). [19,20] For example, Wei et al [21] prepared a3Do rdered mac-roporousC e 0.8 Zr 0.2 O 2 -supported Au catalystw ithal ow T f of 400 8C, andr ecently,N ascimentoe tal.…”