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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.

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Fe-doped CeO2 nano-oxide exhibited superior CO oxidation activity compared to pristine CeO2 due to its facile reducible nature, enhanced lattice strain, and ample oxygen vacancies.

The present work has been undertaken with an aim to synthesize valuable bio-additive fuels from glycerol acetalization using SnO 2 -based solid acids. Various promoters, namely SO 4 2− , MoO 3 and WO 3 were incorporated to the SnO 2 using a wet-impregnation method. An extensive physicochemical characterization has been achieved by means of XRD, BET surface area, BJH analysis, FT-IR, pyridine adsorbed FT-IR, NH 3 -TPD, ICP-OES and XPS techniques. The BET surface area of SnO 2 is significantly improved from 11 to 32, 56 and 41 m 2 g −1 after the addition of the WO 3 , MoO 3 , and SO 4 2− promoters, respectively. The XPS studies revealed that Sn is present in the +4 oxidation state, whereas Mo, W and S are in the +6 oxidation state in the prepared samples. In addition, the SO 4 2− /SnO 2 sample contained super acidic sites, along with strong-and medium-acidic sites. The amount of acidic sites was found to be 46.47, 61.81, 81.45 and 186.98 μmol g −1 for the SnO 2 , WO 3 /SnO 2 , MoO 3 /SnO 2 , and SO 4 2− /SnO 2 samples, respectively. The pyridine adsorbed FT-IR studies revealed the existence of a superior quantity of Brønsted acidic sites than Lewis acidic sites in the synthesized catalysts. Promoted SnO 2 catalysts exhibited a promising catalytic performance for glycerol acetalization with acetone and furfural, and the activity of the catalysts was found to increase in the following order: SnO 2 < WO 3 /SnO 2 < MoO 3 /SnO 2 < SO 4 2− /SnO 2 . The outstanding performance of the SO 4 2− /SnO 2 catalyst is mainly due to the existence of a large amount of acidic sites associated with the super acidic sites. The achieved optimum glycerol conversions with acetone and furfural were ~98 and 99% over the SO 4 2− /SnO 2 catalyst, respectively.

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