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Highlights: [•] CuO-CeO2/SBA-15 catalysts were prepared by a novel solid state impregnation method. [•] Both copper species and ceria can be well dispersed. [•] In comparison with wet impregnation, the solid state impregnation derived catalyst owns increased interfacial CuO-CeO2 entities and enhanced interfacial interactions. [•] CuO-CeO2/SBA-15 catalyst from solid state impregnation shows enhanced CO-PROX activity and good tolerance to CO2 and H2O. [Copyright &y& Elsevier]

The development of efficient method for preparation of well-performed catalyst is an attractive topic in heterogeneous catalysis. Conventional route to obtaining mixed oxide catalysts is based on wet chemical methods. In the present study, a novel solid state method was proposed to fabricate NiO-CeO 2 catalyst by directly mixing metal precursors (nickel nitrate hydrate and cerium nitrate hydrate) and the subsequent calcination, omitting the common drying procedure in wet preparations. The preparation process was tracked by thermogravimetry-differential thermal analysis (TG-DTA) and obtained catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 physisorption, powder X-ray diffraction (XRD), Raman spectroscopy, H 2 temperature programmed reduction (H 2 -TPR) and tested in the model reaction of NO reduction by CO. Results showed that simultaneous decomposition of the mixed nitrates was occurred, suggesting cooperative interaction between the precursors. Moreover, in comparison with wet impregnation method, the catalyst from solid state preparation displayed not only improved textual properties (larger surface area and enriched porous structure), but also enhanced interfacial interactions between nickel and ceria, which promoted the bulk doping, surface dispersion of nickel species and the reduction of surface oxygen species. As a result, the catalytic performance in NO + CO reaction was significantly upgraded. Based on the preliminary results of this study, it is supposed the solid state preparation may open a convenient and versatile pathway to fabricate mixed oxide catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel effect of strong acid-redox interface hinders NH 3 -SCR activity is reported. • Three Ce 2 (SO 4) 3 -CeO 2 catalysts with distinct interfaces are constructed. • NO adsorption and oxygen vacancy formation are limited after Ce 2 (SO 4) 3 addition. • Weak interface promotes NO activation and the formation of active nitrites. The occurrence of NH 3 -SCR (selective catalytic reduction of NO with NH 3) reaction on catalyst surface typically requires acid and redox sites. However, the role of acid-redox interaction on NH 3 -SCR performance is still obscure due to complex acidities and entangled acid-redox sites. Herein, three types of model Ce 2 (SO 4) 3 -CeO 2 catalysts with distinct interfaces are constructed to reveal the effect of acid-redox interaction on NH 3 -SCR performance. That is, SO 4 2-/CeO 2 -VS (vapor sulfation of ceria) with strong acid-redox interfacial contact, SO 4 2-/CeO 2 -WI (wet impregnation), and SO 4 2-/CeO 2 -SG (solid grinding) with limited interfaces. It is found the redox property is significantly disturbed as a result of the electron-withdrawing effect from the sulfate. Theoretical result unravels that the introduction of Ce 2 (SO 4) 3 retards the oxygen vacancy formation over CeO 2. Due to restricted interfaces in SO 4 2-/CeO 2 -SG, the negative influence from acid sites is greatly alleviated. Further mechanism study discloses the weakened acid-redox interaction actually changes the nature of surface NO x species, resulting in the generation of reactive species (*O-N-O* and cis -N 2 O 2 2-) and the promotion of surface reaction via Langmuir-Hinshelwood (L-H) mechanism. [ABSTRACT FROM AUTHOR]

CeO 2 and its derivatives are potential photocatalysts due to their superior redox ability, abundant oxygen defects and cost effectiveness. However, little attention has been paid to the crystal-plane-dependent interactions in CeO 2 -based nanocomposites for photocatalytic hydrogen evolution. In this work, CeO 2 /g-C 3 N 4 were synthesized with tunable CeO 2 crystal planes ({110}, {100}, and {111}). Photoelectrochemical, XPS, Raman, ESR results suggested that the electron-separation efficiency, oxygen defects and Ce 3+ /Ce 4+ reversibility pairs were greatly dependent on the crystal-faceted CeO 2 and g-C 3 N 4 interaction, and the photocatalytic performances of hydrogen evolution under visible light irradiation were in the order: CeO 2 {110}/g-C 3 N 4 >CeO 2 {100}/g-C 3 N 4 >CeO 2 {111}/g-C 3 N 4 >g-C 3 N 4 . Furthermore, the FT-IR, XPS and density functional theory (DFT) calculations shown that the different properties of CeO 2 /g-C 3 N 4 were resulted from the built-in electric field at the interface, and more intensive electronic interaction was found on CeO 2 {110}/g-C 3 N 4 , leading to the efficient separation and transfer of photo-generated electrons under light illumination. [ABSTRACT FROM AUTHOR]

In this work, CeO 2 nanocubes hybridized g-C 3 N 4 composites had been facilely synthesized to investigate the interfacial effects on photocatalytic water splitting. The c-CeO 2 /g-C 3 N 4 composites exhibited the superior photocatalytic hydrogen evolution under visible light irradiation. The optimal c-CeO 2 loading content was 5 wt%, with the H 2 evolution of 4300 μmol g −1 for 5 h illumination, higher than that of pristine CeO 2 , g-C 3 N 4 and irregular CeO 2 nanoparticles/g-C 3 N 4 . Moreover, UV–vis DRS, PL spectra and photoelectrochemical measurements demonstrated that 5 wt% c-CeO 2 /g-C 3 N 4 composite possessed more visible light adsorption and faster charge transfer, which was attributed to the stronger interfacial effects through the presence of the hydrogen bond and p-π hybrid between c-CeO 2 {100} and g-C 3 N 4 , revealed by the FT-IR and XPS results. The work suggested that engineering the structures of the CeO 2 and g-C 3 N 4 interface could be an effective strategy to obtain excellent photocatalysts. [ABSTRACT FROM AUTHOR]

In this work, Cu 2 O–reduced graphene oxide (rGO) composites were synthesized with tunable Cu 2 O crystal facets ({1 1 1}, {1 1 0} and {1 0 0} facets). The degradation performance of methylene blue under visible light was ranked: o-Cu 2 O{1 1 1}–rGO > d-Cu 2 O{1 1 0}–rGO > c-Cu 2 O{1 0 0}–rGO. UV–vis diffuse reflectance and photoluminescence spectra showed that o-Cu 2 O–rGO exhibited the enhanced visible-light absorption and the faster charge-transfer rate. Furthermore, X-ray photoelectron spectroscopy and Raman characterizations showed that o-Cu 2 O–rGO was beneficial for the stabilization of Cu + species and the formation of oxygen defects. With the help of in-situ electron spin resonance (ESR), more superoxide radicals were detected over o-Cu 2 O–rGO, which promoted organic pollutants degradation. The above results confirmed that the catalytic behaviors of three Cu 2 O–rGO composites were related to the electronic structures and interfacial connections. The o-Cu 2 O{1 1 1}–rGO displayed the superior performance, for the highly-active coordinated unsaturated Cu and the intensive interfacial connection, which was beneficial for the rapid the photo-generated electron transfer and the formed active superoxide species. This study showed that engineering the interfacial structures could provide a scientific basis for the design of efficient photo-catalysts. [ABSTRACT FROM AUTHOR]