The development of efficient visible light photocatalysts based on ceria (CeO2) requires precise control over both morphology and electronic band structure. Herein, a facile one-pot hydrothermal method is reported for the preparation of crystallographically well-defined ceria nanocubes featuring enhanced photocatalytic response under visible light irradiation. The proposed approach relies on the in situ structural incorporation of 1,10-phenanthroline during crystal growth. Unlike conventional doping or surface functionalisation strategies, this method yields organic-inorganic nanostructured hybrid materials where the organic moiety is effectively incorporated into the fluorite-type ceria lattice through the formation of Ce-N coordination bonds while preserving the cubic morphology enclosed by reactive {100} facets and simultaneously increasing the specific surface area. Diffuse reflectance UV-Vis spectroscopy and valence band XPS analyses reveal that this integration induces the appearance of N 2p intraband gap states associated with the Ce-N bonds, resulting in a significant narrowing of the optical band gap and extending the light absorption edge into the visible region. Consequently, these organoceria hybrids exhibit a remarkable synergistic enhancement in photocatalytic hydrogen production via ethanol photoreforming under simulated solar irradiation, with hydrogen evolution rates being 7.5 times higher than those of pristine ceria nanocubes. This work demonstrates the potential of organic ligand-assisted lattice engineering as a versatile approach for tailoring the optoelectronic properties of ceria, thus opening new avenues for sustainable solar-to-chemical energy conversion.

A multidisciplinary approach has been followed for the development of structured catalysts based on 3D-printed metallic honeycomb monoliths, which allows overcoming some of the barriers that limit the industrial application of significant catalytic processes such as those related to CO2 valorization. In particular, nickel and/or cerium-containing catalysts have been incorporated into stainless steel honeycombs and evaluated in the Dry Reforming of Methane (DRM) reaction. Moreover, taking advantage of the conductive nature of the metallic substrate, a methodology that allows the incorporation of the active phase by electrochemical deposition has been implemented. The prepared catalysts were characterized by SEM coupled EDX compositional analysis, Xray fluorescence, X-ray diffraction, X-ray Photoelectron Spectroscopy and Temperature-Programmed Reduction. In contrast to the catalyst where cerium and nickel were co-deposited, the catalyst obtained by sequential electrodeposition of Ce (first) and Ni (second) proved to be highly active and stable in the DRM process, with conversions of both CH4 and CO2 above 90 % and H2/CO ratio of ca. 0.8 at 750 degrees C for more than 40 h. Moreover, the catalyst kept its good performance after doubling the flow proving its great potential for a real application at higher scale.

This study presents a novel bimetallic iron–silver phosphate (FeAg(PO4)2) nanocatalyst. We detail a one-pot hydrothermal synthesis of FeAg(PO4)2, a hetero-structured composite dominated by silver phosphate (Ag3PO4) and iron (III) phosphate (FePO4). Characterization techniques include X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV–Vis diffuse reflectance, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis, transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray mapping, revealing a mesoporous structure with a surface area of 55.60 m2/g and a pore size of 2 nm. Machine learning, particularly the Random Forest Tree model, predicted energy per atom of − 7.17 eV, and a band gap of 1.87 eV, indicating high stability and suitability for catalysis. The nano-catalyst showed high efficiency in synthesizing benzimidazole derivatives (up to 95

Confronting escalating challenges in energy security and environmental sustainability has intensified interest in renewable sources for fuels and chemicals. Among the most promising alternatives, sugars derived from biomass are emerging as a cornerstone in advancing an environmentally sustainable economy. Within this framework, the development of sunlight-driven carbohydrate oxidation is of significant interest, as it enables the production of a broad spectrum of high-value, bio-sourced chemicals through eco-friendly processes. Gold nanoparticles (Au NPs) immobilized on inorganic supports have demonstrated considerable potential in this area, although the methodology still requires further exploration. In this study, we explored the selective oxidation of glucose into the corresponding gluconic acid salt in presence of a novel Au/Ni-Al-Zr-layered double hydroxide (LDH) photocatalyst under standardized A.M. 1.5 G light illumination. To optimize the photocatalytic conditions, an experimental plan is herein proposed, highlighting the critical influences of both catalyst loading and pH. In optimal conditions, the Au catalyst demonstrated a high efficiency, achieving 87% glucose conversion and 100% selectivity towards gluconic acid in only 90 min. By means of long-pass filters to select the incident light energy to the photocatalytic reactor, we evidenced that the charge transfer processes were occurring from the Ni-Al-Zr LDH support to the gold nanoparticles, thus opening new directions towards further photocatalyst modifications. This work underlines the potential of Au/LDH materials for sunlight-driven photocatalysis and provides a pathway for the sustainable production of high-value chemicals from renewable biomass sources.

A novel facile method to prepare ceria nanocrystals with well-defined cubic morphology and enhanced optical properties is herein disclosed. Both the decrease in the band gap and the appearance of absorption edges above 400 nm, which redound in a significant absorption of visible light, are accomplished by simply incorporating in situ different amounts of a typical chelating bidentate ligand, 1,10-phenanthroline, during the synthesis of these ceria nanocubes. Such a remarkable effect has been tentatively connected with the ability of this nitrogen-containing heterocyclic compound to coordinate Ce3+ cations from the ceria precursor salt, thus yielding intermediate N 2p states along the band gap of the oxide.

Lignocellulosic biomass upgrading is a pivotal axis in the transition from an economy based on fossil resources to one reliant on renewable biomass resources. Within this context, low-cost Zr-doped MgAl-LDH@Aunano-catalysts are reported in this study as efficient catalysts to synthesize bio-based succinic acid. A series of Zr-doped MgAl-LDH and Au/Zr-doped MgAl-LDH catalysts have been successfully prepared. All catalysts have a lamellar double hydroxide structure LDH even after enrichment with Zr and addition of Au.Au NPs have small average sizes ranging from 1.2 to 8.5nm. The materials under study showed exalted catalytic performances in the direct synthesis of succinic acid from bio based furfural via an aqueous phase oxidation reaction with H2O2. 84% of furfural conversion and 99% selectivity towards succinic acid were achieved.A positive synergy between Zr and Au NPs is highlighted and related to this catalytic performances improvement.

The ability to mimic protein-based oxidase with multi-functional inorganic nanozymes would greatly advance biomedical and clinical practices. Praseodymia (PrOx) nanorods (NRs) and nanoparticles (NPs) have been syn-thesized using hydrothermal and precipitation methods. Both PrOx catalysts with different morphologies exhibit significantly higher oxidase-like activities (Michaelis-Menten constant Km <= 0.026 mM) than commercial PrOx and most so-far-reported artificial enzymes. One of the substrates, dopamine, can be oxidized and further polymerized to generate polydopamine in acidic conditions. Akin to CeO2, which is a well-studied nanozyme, a different mechanism involving holes+, oxygen vacancies and oxygen mobility over PrOx catalysts has been proposed in this work. However, fluoride ions were found to impose opposite effects on the oxidase-mimicking activity of PrOx and CeO2, implying a promising path for the exploration of new nanozymes. In support of this, PrOx was further applied in colorimetric sensing of L-cysteine and fluoride with high sensitivity.

The development of photoresponsive textiles with high color contrast, sunlight response, fast coloration/bleaching, and reversible properties has been a major quest for anticounterfeiting, camouflage, UV protection, and fashion. WO3 materials are promising building blocks for textile applications, but their application has been limited by their slow color bleaching under ambient conditions and limited sunlight response. Herein, innovative tungsten oxide-based materials with tunable photochromism were produced by a low-cost, single-step, and scalable solvothermal process in the presence of different structure-directing agents, and the most promising ones were screen-printed on fabrics to produce light-responsive smart textiles. The influence of the structure-directing agent type (polyethylene glycol, hexadecyltrimethylammonium bromide, polyoxyethylene(10) cetyl ether, Pluronic F127, and polyvinylpyrrolidone (PVP)) on the morphology, structure, composition and photochromism of the WO3-based materials was assessed, toward enhancing their color contrast and coloration/bleaching rates and endowing a sunlight response. All WO3-based materials exhibited UV/sunlight-responsive properties, with the materials prepared with PVP presenting the best performance, featuring 13x faster coloration than that of other WO3-based materials reported in the literature (7 min vs 60-90 min) and up to 2x higher total color difference (21.4-50.6 vs 25.2-25.8). These improvements were assigned to their Lindqvist-type hexatungstic acid structure hybridized with PVP, while the remaining materials were composed of WO3H2O and WO3. The WO3_PVP-based materials led to high-performance photoswitchable textiles under sunlight and UV irradiation, changing color from white to blue in 3-7 min and bleaching in 3-7 h. The smart textiles presented fast hydrobleaching, especially the fabric based on WO3 prepared using PVP with higher molecular weight, which hydrobleached in up to 20 s, surpassing reported works on WO3-modified fibers. This work opens horizons for the design of engineered UV/sunlight-responsive WO3-based materials and textiles with hydrobleaching properties through straightforward scalable processes, offering potential prospects for smart clothing and optical sensors.

Ceria (CeO2) is a ubiquitous component in catalysts for environmental protection processes, especially those devoted to CO2 valorisation. Aimed at preparing ceria-based nanomaterials with enhanced CO2 adsorption and activation properties, both the surface acid-base and redox features of ceria nanocubes were modulated by a novel, simple, wet chemistry synthetic strategy consisting of their coating with yttria (Y2O3) layers of variable thickness in the nanometre scale. The as-synthesised samples were characterised with special attention to their surface basicity and reducibility. Characterisation results revealed that the surface doping with yttria not only improved both the reducibility at low temperature and CO2 adsorption capacity of ceria nanocubes, but also introduced a variety of basic sites with different strength. Finally, the careful control of the yttria layer thickness allowed to modulate these effects and thereby the ability of nanostructured ceria to adsorb and activate the CO2 molecule.

Despite the increasing economic incentives and environmental advantages associated to their substitution, carbon-rich fossil fuels are expected to remain as the dominant worldwide source of energy through at least the next two decades and perhaps later. Therefore, both the control and reduction of CO2 emissions have become environmental issues of major concern and big challenges for the international scientific community. Among the proposed strategies to achieve these goals, conversion of CO2 by its reduction into high added value products, such as methane or syngas, has been widely agreed to be the most attractive from the environmental and economic points of view. In the present work, thermocatalytic reduction of CO2 with H2 was studied over a nanostructured ceria-supported nickel catalyst. Ceria nanocubes were employed as support, while the nickel phase was supported by means a surfactant-free controlled chemical precipitation method. The resulting nanocatalyst was characterized in terms of its physicochemical properties, with special attention paid to both surface basicity and reducibility. The nanocatalyst was studied during CO2 reduction by means of Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). Two different catalytic behaviors were observed depending on the reaction temperature. At low temperature, with both Ce and Ni in an oxidized state, CH4 formation was observed, whereas at high temperature above 500 °C, the reverse water gas shift reaction became dominant, with CO and H2O being the main products. NAP-XPS was revealed as a powerful tool to study the behavior of this nanostructured catalyst under reaction conditions.

In this work, a simple one-step thermal oxidation process was established to achieve a significant surface increase in {110} and {111} nanofacets on well-defined, pure and Pr-doped, ceria nanocubes. More importantly, without changing most of the bulk properties, this treatment leads to a remarkable boost of their enzymatic activities: from the oxidant (oxidase-like) to antioxidant (hydroxyl radical scavenging) as well as the paraoxon degradation (phosphatase-like) activities. Such performance improvement might be due to the thermally generated sawtoothlike {111} nanofacets and defects, which facilitate the oxygen mobility and the formation of oxygen vacancies on the surface. Finally, possible mechanisms of nanoceria as artificial enzymes have been proposed in this manuscript. Considering the potential application of ceria as artificial enzymes, this thermal treatment may enable the future design of highly efficient nanozymes without changing the bulk composition.

Three nanostructured catalysts with low total rare earth elements (REEs) content (i.e., 15 mol.%) were prepared by depositing CeO2 or Ln3+-doped CeO2 (Ln3+ = Y3+ or La3+; Ln/Ce = 0.15) on the surface of ZrO2 nanoparticles, as nanometre-thick, fluorite-type clusters. These samples were subjected to successive reduction treatments at increasing temperatures, from 500 to 900 °C. A characterisation study by XPS was performed to clarify the diffusion process of cerium into the bulk of ZrO2 crystallites upon reduction to yield CexZr1−xO2−δ surface phases, and the influence of the incorporation of non-reducible trivalent REE cations, with sizes smaller (Y3+) and larger (La3+) than Ce4+ and Ce3+. For all nanocatalysts, a reduction treatment at a minimum temperature of 900 °C was required to accomplish a significant cerium diffusion. Notwithstanding, the size of the dopant noticeably affected the extent of this diffusion process. As compared to the undoped ZrO2-CeO2 sample, Y3+ incorporation slightly hindered the cerium diffusion, while the opposite effect was found for the La3+-doped nanocatalyst. Furthermore, such differences in cerium diffusion led to changes in the surface and nanostructural features of the oxides, which were tentatively correlated with the redox response of the thermally aged samples.

This paper presents a study of the surface properties of two Ce/Zr mixed oxides with different reducibility, obtained by applying distinct thermal ageing treatments to an oxide with the composition Ce0.62Zr0.38O2. The surface composition was investigated by XPS. Chemical reactivity of the surface was studied by adsorption of the probe molecules CO2, D-2 and methanol. Nanostructural characterization was carried out by XRD, Raman and high-resolution Eu3+ spectroscopy (FLNS). The characterization showed only slight variations in surface composition and bulk Ce-Zr distribution, but hardy differences concerning the type and strength of acidic surface centres, as well as strong differences in the ability to dissociate hydrogen. Structural variations between both samples were identified by comparing the optical spectra of Eu3+ in surface doped samples.

A very low loading mixed CeO2–TbOx catalyst, supported on MgO, with improved methane total oxidation activity and stability.

It is reported, for the first time, that morphology controlled ceria without any addition of other metal exhibits catalytic activity for selective oxidation of glycerol. Moreover, development of {111} nanofacets plays an important role in both activity and selectivity.

A bimetallic Au-Pd catalyst supported on ceria-zirconia with Au:Pd molar ratio 0.8 has been synthesized using a simultaneous deposition-precipitation method and oxidized at 250, 450, and 700 degrees C in order to modify its particle size, nanostructure, and composition. Combined X-ray energy dispersive spectroscopy (XEDS) and X-ray photoelectron spectroscopy (XPS) analysis clearly evidence that the bimetallic Au-Pd catalyst oxidized at 250 degrees C is made up of a mixture of monometallic Au and Pd and bimetallic Au-Pd nanoparticles with Au:Pd ratios varying over a wide range. Increasing oxidation temperature leads to a stronger interaction between Au and Pd. Meanwhile, a slight increase of particle size and a narrowing of the Au:Pd ratio in the bimetallic nanoparticles take place. Compared with titania and activated carbon supports, the resistance against sintering at high temperatures of Au-Pd metal particles supported on ceria-zirconia is proven to be higher. A synergistic effect has been observed for selective oxidation of benzyl alcohol on these catalysts. The catalytic activity decreases only slightly after oxidation at 450 degrees C. However, oxidation at 700 degrees C results in much lower catalytic activity. Migration of Pd onto Au particles during oxidation of benzyl alcohol enhances the catalytic activity of a physical mixture of monometallic Au and Pd supported on ceria-zirconia catalysts. This fact, jointly with an analysis of the intrinsic activity, reveals the influence of the actual nature of Au-Pd interactions in the bimetallic particles, which points to higher activity of Au@Pd or AuPd@Pd nanostructures on ceria-zirconia supports. (C) 2019 Elsevier Inc. All rights reserved.

This paper describes the results obtained when ultraviolet laser treatment was performed as a surface treatment prior to adhesive bonding for two aeronautical carbon fibre-reinforced plastics based on an epoxy resin prepreg. Different laser-processing parameters were employed, and their effect on the surfaces was analysed through morphological characterisation and wettability studies. X-ray photoelectron spectroscopy measurements were performed to determine the cleaning and activation effects of the treatment. The strength of the bonded joint was studied for laser-treated and manually ground samples. Samples processed under the selected laser conditions exhibited better adhesive behaviour than the manually treated samples, thereby suggesting that ultraviolet laser treatment could be used as an alternative method for surface activation of aeronautical composites based on epoxy resins.

Two series of ceria-praseodymia promoted Ni-alumina catalysts were prepared from two different commercial modified alumina supports by the incipient wetness impregnation method in two successive steps.The resulting materials were characterized in terms of their physico-chemical properties. Furthermore, the as-prepared catalysts were tested for the CO2 methanation reaction. The influence of the nominal Ni loading, molar composition of the Ce-Pr mixed oxide promoter and alumina modifier on the catalytic performance was carefully analyzed. Among these three composition parameters, the alumina dopant and especially the Ni content appear to have by far a much more pronounced effect on both the CO2 conversion and CH4 selectivity as compared to the Ce-Pr mixed oxide composition.

Ceria‐zirconia mixed oxides are widely used as catalysts and catalytic supports. Nevertheless, due to economic and geo‐strategic concerns, reducing and optimizing the lanthanide content in these formulations while preserving or even improving their excellent redox and catalytic properties has become a challenge for current research. In this context, the design of core@shell nanostructures arises as a feasible alternative to achieve the aforesaid goal. In the present work, a new nanostructured ZrO 2 @CeO 2 system based on spherical and mesoporous zirconia cores coated by a well‐dispersed nanometer‐thick ceria layer has been prepared by a novel synthetic approach in 2 different steps: (1) synthesis of the zirconia cores by a sol‐gel method and (2) coating with a thin ceria shell by controlled chemical precipitation. The resulting nanocomposite was characterized by several techniques, which clearly reveal its perfect core@shell nanostructure and enhanced reducibility as compared with pure ceria.

The selective oxidation of veratryl alcohol (VA), a model compound of lignin, with oxygen molecules to produce veratraldehyde (VAld) was studied over monometallic Au, Pd, and bimetallic Au:Pd nanoparticles supported on a Ce0.62Zr0.38O2 mixed oxide for the first time. These bimetallic Au-Pd catalysts with Au:Pd molar ratios from 0.4 to 4.3 were synthesized by the sol-immobilization method. Furthermore, all the catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), N2 physisorption, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy-high angle annular dark field (STEM-HAADF) imaging, energy dispersive X-ray spectroscopy (EDXS), and temperature programmed reduction (TPR) techniques. A synergistic effect between gold and palladium was observed over all the bimetallic catalysts in a wide range of studied Au:Pd ratios. Remarkably, the optimum Au:Pd ratio for this reaction was 1.4 with a turnover frequency of almost six times larger than for the monometallic gold and palladium catalysts. Selectivity to veratraldehyde was higher than 99% for the monometallic Au, Pd, and all the bimetallic Au-Pd catalysts, and stayed constant during the reaction time.