A series of inverse TiO2/CeO2 catalysts were prepared by the impregnation method and their catalytic performances for the selective catalytic reduction of NO by NH3 have been tested with and without SO2 and/or H2O. Compared with the normally discussed CeO2/TiO2 catalyst, the advantage of inverse TiO2/CeO2 catalyst was not only shown a good low temperature catalytic activity (150–250 °C), but also exhibited much better SO2 resistance performances with the existence of 200 ppm SO2 and/or 5 vol.% H2O at 300 °C. Furthermore, SO2 had more significant inhibitory effect on catalytic activity than H2O based on the configuration differences of Ce–Ti-based catalysts. These catalysts were investigated by means of TG-DTA, XRD, BET, in situ DRIFT, XPS and H2-TPR. The results demonstrated that the sulfation of these samples under reactive conditions mainly generated three different kinds of sulfate species including NH4HSO4, surface and bulk-like metal sulfates (mainly interacted with cerium species). The formed metal sulfates blocked the active sites of Ce–O–Ti and resulted in the deactivation of CeO2/TiO2. Although metal sulfates were also formed over TiO2/CeO2, NH3-SCR could still proceed and that was similar as the reaction system with the use of sulfated CeO2 as the catalyst. Meanwhile, the interactions between SO2 and Ce–Ti-based catalysts were discussed in detail and an adsorption model of SO2 was proposed.

Getting insight into the influence of SO2 on TiO2/CeO2 for the selective catalytic reduction of NO by NH3

Electrochemical deposition is a facile strategy to prepare functional materials but suffers from limitation in thin films and uncontrollable interface engineering. Here we report a universal electrosynthesis of metal hydroxides/oxides on varied substrates via reduction of oxyacid anions. On graphitic substrates, we find that the insertion of nitrate ion in graphene layers significantly enhances the electrodeposit–support interface, resulting in high mass loading and super hydrophilic/aerophobic properties. For the electrocatalytic oxygen evolution reaction, the nanocrystalline cerium dioxide and amorphous nickel hydroxide co-electrodeposited on graphite exhibits low overpotential (177 mV@10 mA cm−2) and sustains long-term durability (over 300 h) at a large current density of 1000 mA cm−2. In situ Raman and operando X-ray diffraction unravel that the integration of cerium promotes the formation of electrocatalytically active gamma-phase nickel oxyhydroxide with exposed (003) facets. Therefore, combining anion intercalation with cathodic electrodeposition allows building robust electrodes with high electrochemical performance.

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Anion insertion enhanced electrodeposition of robust metal hydroxide/oxide electrodes for oxygen evolution.

https://espace.library.uq.edu.au/view/UQ:ab7c7f5/UQab7c7f5_OA.pdf

Active corrosion protection by a smart coating based on a MgAl-layered double hydroxide on a cerium-modified plasma electrolytic oxidation coating on Mg alloy AZ31

In this report, a novel nanocomposite of highly dispersed CeO2 on a TiO2 nanotube was designed and proposed as a peroxidase-like mimic. The best peroxidase-like activity was obtained for the CeO2/nanotube-TiO2 when the molar ratio of Ce/Ti was 0.1, which was much higher than that for CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, or CeO2/nanoparticle-TiO2 with a similar molar ratio of Ce/Ti. Moreover, in comparison with other nanomaterial based peroxidase mimics, CeO2/nanotube-TiO2 nanocomposites exhibited higher affinity to H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB). Kinetic analysis indicated that the catalytic behavior was in accordance with typical Michaelis–Menten kinetics. Ce3+ sites were confirmed as the catalytic active sites for the catalytic reaction. The first interaction of surface CeO2 with H2O2 chemically changed the surface state of CeO2 by transforming Ce3+ sites into surface peroxide species causing adsorbed TMB oxidation. Compared with CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, and CeO2/nanoparti...

Highly Dispersed CeO2 on TiO2 Nanotube: A Synergistic Nanocomposite with Superior Peroxidase-Like Activity

The catalysts of three-dimensionally ordered macroporous Ce1−xZrxO2-supported gold nanoparticles for soot combustion: The metal–support interaction

This article presents an XPS study of Ce 3d emission spectra dominated by atomic multiplet effects in core level spectroscopy of rare earth compounds (Ce oxides). Core level spectroscopy has been used to study the electronic states of Ce 3d5/2 and Ce 3d3/2 levels in Ce4+ and Ce3+ states. The well-resolved components of Ce 3d5/2 and Ce 3d3/2 spin-orbit components, due to various final states (4f0, 4f1, 4f2 configurations), were determined on 3d XPS spectra from commercial powders (CeO2, CePO4).

These results were used to study the 3d spin-orbit component of mixed cerium-titanium oxide.

This compound was prepared by co-melting commercial powders of CeO2 and TiO2 at 1800 K under air using a solar furnace with a flux density of 16 MW.m−2 at the focal point of the parabolic concentrator. The mixed oxide Ce2Ti2O7 was produced and contained Ce(III) species which may be reactive with water to give back the initial metal oxides and generate hydrogen, a valuable product considered as a promising energy carrier in the future in replacement of oil.

The 3d photoemission spectra revealed the presence of mixed components attributed to mainly Ce(III) and Ce(IV) species. Copyright © 2008 John Wiley & Sons, Ltd.

Ce 3d XPS investigation of cerium oxides and mixed cerium oxide (CexTiyOz)

(La2O3)1-x (CeO2)2x (ZrO2)2 mixed oxides (LCZ) where 0 ≤ x ≤ 1 were synthesised from commercial La2O3, CeO2 and ZrO2 powders and co-melted in a 2-kW solar furnace. These samples were re-oxidised in air at temperatures that ranged from 900 K to 1100 K. The microstructures of the LC, LCZ and CZ oxides were investigated by XPS and XRD. Core-level spectroscopy (XPS) has been used to study electronic states (III) and (IV) of the Ce 3 d5/2 and Ce 3 d3/2 levels. The resolved components of the Ce 3 d3/2,5/2 features were identified. The rate of Ce3+ and Ce4+ states were calculated for different values of x (0.1–1). The nature of the chemical bonds of Ce and O were determined from the Ce 3 d3/2,5/2 and O 1 s photoelectron peaks, respectively.The XRD study revealed the presence of solid solutions (LCZ and CZ). The presence of crystalline phases (pyrochlore and fluorite-like structures) depends on the value of x. A decrease in the lattice parameter was observed with increasing x. La atoms were substituted by Ce atoms in a solid solution, and the oxygen vacancies were filled. The amount of fluorite-like phase increases with an increasing amount of Ce atoms. Copyright © 2012 John Wiley & Sons, Ltd.

An XPS investigation of (La2O3)1‐x (CeO2)2x (ZrO2)2 compounds

SiN x , SiO x and SiO x H y deposits containing various hydrogen concentrations were prepared in a plasma enhanced chemical vapour deposition (PECVD) reactor using SiH 4 , NH 3 and N 2 O as precursor gases. These deposits were made for anti-reflection coatings on polymer substracts. In this work, we present a study of the compositions and the chemical environments of silicon, oxygen and nitrogen in these films by using XPS, XAES and FTIR characterization methods. It is shown that the Sio x N y deposits are constituted by various silicon environments which can be described by the presence of Si(O x N y H z ) tetrahedra with x + y + z = 4. The amount of Si-H bonds increases in the deposits when the nitrogen concentration increases. Si-OH chemical bonds were detected for low nitrogen concentration.

XPS and FTIR study of silicon oxynitride thin films

Solar preparation of SiOx (x ≈ 1) nanopowders from silicon vaporisation on a ZrO2 pellet. XPS and photoluminescence characterisation

XPS core levels and XPS valence band spectra were recorded on air-exposed or Ar + sputtered surfaces of a-SiC x :H and a-SiO x C y :H PECVD thin films prepared from various organosilicon precursors with changing the preparation conditions. Their compositions and their XPS valence band spectra were compared with those obtained for SiC, SiO 2 and PDMS conventional polymer. From the calculated compositions and the valence band spectra obtained on air-exposed surfaces, we were able to show the evolutions of the polymeric nature of the films with changing the monomer precursor or the preparation conditions. Futhermore, variations in chemical compositions and valence band spectra induced by Ar sputtering have been shown and also used to reveal differences between siloxane-like plasma polymers and more inorganic amorphous materials. Informations provided by these investigations were well consistent with other characterization results obtained from XPS core level peak fittings as well as from FTIR and NMR analyses.

D. Perarnau

Papers

Ce 3d XPS investigation of cerium oxides and mixed cerium oxide (CexTiyOz)

An XPS investigation of (La2O3)1‐x (CeO2)2x (ZrO2)2 compounds

XPS and FTIR study of silicon oxynitride thin films

Solar preparation of SiOx (x ≈ 1) nanopowders from silicon vaporisation on a ZrO2 pellet. XPS and photoluminescence characterisation

XPS and XPS valence band characterizations of amorphous or polymeric silicon based thin films prepared by PACVD from organosilicon monomers