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The reaction mechanism of CO2 and methanol toward dimethyl carbonate over ZrO2 in the liquid phase is elucidated by means of ATR-IR augmented by MCR-ALS analysis.

Resumo A limitação de suporte de vida tem sido aplicada na terapia intensiva em quadros de doença irreversível e tratamento improdutivo. Nessas situações, cuidados paliativos visam prevenir e aliviar o sofrimento e tornam-se essenciais para propiciar atenção específica e contínua para o paciente e sua família, possibilitando morte digna. Este estudo envolveu pesquisa qualitativa realizada com 37 profissionais da equipe multidisciplinar em unidade de terapia intensiva clínico-cirúrgica de hospital público em Curitiba, Paraná, Brasil. A análise temática dos dados estabeleceu quatro temas, que permitiram investigar o conhecimento da equipe sobre eles e elaborar ações de cuidados paliativos a pacientes com limitação de suporte de vida em terapia intensiva. Os profissionais reconheceram a importância dos cuidados paliativos à população em apreço naquela unidade. Abstract The Limitation of Life Support has been applied in intensive care in cases of irreversible disease and futile treatment. In these situations, palliative care aims at preventing and alleviating suffering. It becomes essential to provide specific and ongoing care to patients and their families, enabling death with dignity. This study involved qualitative research carried out with 37 health professionals working within the multidisciplinary team in a Clinical Surgical Intensive Care Unit of a public hospital located in Curitiba, Paraná, Brazil. Through the thematic analysis of the data, four themes were formed, which made it possible to investigate the knowledge of the team regarding the subject and develop palliative care actions for patients with limitation of life support in intensive care. The professionals recognized the importance of Palliative Care for these patients in the Intensive Care Unit. Resumen La limitación del soporte de vida se ha aplicado en terapia intensiva en cuadros de enfermedad irreversible y ante tratamientos improductivos. En estas situaciones, los cuidados paliativos surgen con el objetivo de prevenir y aliviar el sufrimiento y se tornan esenciales para propiciar una atención específica y continua para el paciente y su familia, posibilitando una muerte digna. Este estudio implicó una investigación cualitativa realizada con 37 profesionales del equipo multidisciplinario de una unidad de cuidados intensivos clínico-quirúrgica de un hospital público situado en Curitiba, Paraná, Brasil. El análisis temático de los datos estableció cuatro temas, que permitieron investigar el conocimiento del equipo sobre estos y elaborar acciones de cuidados paliativos para pacientes con limitación del soporte de vida en cuidados intensivos. Los profesionales reconocieron la importancia de los cuidados paliativos para la población en cuestión en dicha unidad.

The photochemical activity of the recently proposed CeO2–ZnO photocatalytic material active under visible light has been improved by means of significant modifications of its morphology. A polymeric templating agent (Pluronic) has been used in the synthesis obtaining a particle morphology based on hollow spheres that is better defined in the case of high template concentration. The charge separation ability and the light-induced surface electron transfer under irradiation with visible polychromatic light in various ranges of wavelengths has been investigated by electron paramagnetic resonance. The reactivity of the photogenerated holes has been monitored by the spin trapping technique in the presence of DMPO. The hollow spheres morphology achieved through the synthesis here reported leads to systems with a higher photoactivity under visible irradiation than the same system displaying the classic platelets morphology. A parallel increase of the photocatalytic activity of this novel system in pollution remediation reactions is therefore predictable.

Heterogeneous photocatalysis may diversify and augment access to unconventional water sources like wastewater. However, the energy embodied in water treatment and supply in photocatalytic systems make process efficiency considerations and environmental impacts assessment of primary relevance towards the setting of sustainable strategies. In this work, we evaluated the degradation rate of phenol in water by using different photocatalysts based on zinc oxide doped with rare earth elements. Aiming at identifying the best operating conditions that couple the highest degradation efficiency with the lowest environmental burdens, the results of an experimental design face centred model were combined to life cycle assessment. Based on previous works of the authors, the concentration of photocatalyst, type of rare earths used as dopant, its precursor and dopant concentration in the photocatalyst constituted the set of explanatory variables. Cumulative energy demand and IPCC 2013 GWP 100y were used as life cycle impact assessment methods. The results show that the highest degradation efficiency is obtained with 1700 mgL−1 of cerium-doped zinc oxide from nitrate precursor. However, setting the photocatalyst concentration at 800 mgL−1 may be preferable to reduce the overall environmental impact, mainly associated with the input of electrical energy and the synthesis of the material. Advanced oxidation processes like the heterogeneous photocatalytic process investigated in this study are promising ways to achieve high standards of wastewater purification and environmental protection. To this aim, the chance of exploiting the solar light to promote photocalysis and the possibility to hold the catalyst on supports that may facilitate its recovery for regeneration are of great interest to scale this technique up to real systems at lower economic and environmental cost.

Engineering defects in semiconducting metal oxides is a challenge that remains at the forefront of materials chemistry research. Nitrogen has emerged as one of the most attractive elements able to tune the photochemical and photocatalytic properties of semiconducting oxides, boosting visible-light harvesting and charge separation events, key elements in promoting solar driven chemical reactions. Doping with nitrogen is also a strategy suggested to obtain p-type conduction properties in oxides showing n-type features in their pristine state and to impart collective magnetic properties to the same systems. Here, we review the evolution in the understanding of the role of nitrogen doping in modifying the photochemical and electronic properties of the most common semiconducting oxides used in mentioned applications including: TiO2, ZnO, SnO2 and zirconium titanates. With an emphasis on polycrystalline materials, we highlight the unique role of Electron Paramagnetic Resonance (EPR) spectroscopy in the direct detection of open-shell N-based defects and in the definition of their structural and electronic properties. Synthetic strategies for the insertion of nitrogen defects in the various matrices are also discussed, along with the influence of the corresponding low-lying energy states on the general electronic properties of the doped solids., Engineered nitrogen defects in semiconducting oxides imparts appealing photophysical and photochemical properties to the materials which can be selectively addressed through EPR spectroscopy.

Two nanocomposites of different layer thicknesses were synthesized by impregnation of a rutile titania support with a reduced ceria solution. An in situ diffuse reflectance infrared fourier-transform spectroscopy-mass spectrometry study of these materials, compared with the parent single oxides, has shown remarkable differences in the interaction with ethanol depending on the layer thickness and the environment (oxidizing/reducing). Under anaerobic conditions, it was found that the surface-support interaction stabilized the ceria in the reduced form (Ce3+) in a wide range of temperature. The intrinsic characteristics of these materials were proven useful in the dehydrogenation of ethanol to acetaldehyde at low temperature since they inhibited further oxidation products (typical in the case of bulk ceria) and dehydration products (such as ethylene, the main product for bulk titania), and even promoted aldolic condensation to crotonaldehyde due to their modified acid/base properties. Interestingly, this highly selective oxidation is obtained without the need of using expensive noble metals as catalysts or hydrogen to keep the ceria reduced.

This study elucidates the working mechanism upon visible light exposure of the mixed C3N4–ZnO material. Structural (XRD), morphological (TEM) and optical (UV-vis spectroscopy) measurements have highlighted the intimate contact established at the interface of the biphasic solid and enhanced photoactivity arising under visible irradiation with respect to the pristine compounds. Electron paramagnetic resonance (EPR) spectroscopy analysis coupled with in situ irradiation, performed at 77 K, and supported by accurate simulations, demonstrated that the charge carrier dynamics at the C3N4–ZnO interface is governed by a direct Z-scheme heterojunction mechanism rather than that of a type-II heterojunction system. The experimental results suggest that the photoexcited electrons in the ZnO conduction band annihilate the holes in the C3N4 valence band, as in a solid direct Z-scheme system, allowing an improved charge carrier separation and stabilizing both electrons and holes at the best reductive and oxidative potentials, respectively.

The preparation of smart Ln:ZrO2@SiO2 nanoplatforms with grafted photosensitizer (Rose Bengal) which couple optical imaging with photo-dynamic therapy (PDT) is presented. A careful control of the lanthanide dopant loading is considered to enhance the photoemission properties of the lanthanide ions (Er, Pr, Yb) inside the ZrO2 crystal structure. The nanosystem with the lowest lanthanide loading maintains the size, phase and morphology of pristine ZrO2 nanoparticles and exhibit the best performances in term of the overall luminescence properties. Upon functionalization with a silica shell to covalently bound Rose Bengal, a theranostic platform is prepared which is very efficient in singlet oxygen generation, as demonstrated by EPR and UV–vis spectroscopy studies. Preliminary cell viability tests show that while both pristine and Ln doped ZrO2 nanoparticles do not exert cytotoxicity, neither upon illumination nor in dark condition, Rose Bengal grafted samples are able to significantly reduce cell viability under light exposure, thus confirming the high potential of these nanoparticles as PDT tools.

The presence of pollutants in water systems is a universal threat. In this study, ZnO based materials and enzyme hybrid materials were evaluated for their ability to remove six emerging wastewater pollutants (namely diclofenac, naproxen, iopamidol, imidacloprid, bisphenol A and 2,4-dichlorophenol). These materials were tested in their free form as well as supported on poly(styrene-co-maleic anhydride) (SMA) nanofibre mats fabricated through the process of electrospinning. The SMA nanofibres were fully characterized using Attenuated Total Reflectance-Fourier Transform InfraRed spectroscopy (ATR-FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Degradation profiles of the activity of these and the Ce-doped ZnO materials in their free form showed good removal efficacy of all the contaminants even in a mixed matrix environment which mimics a real scenario. By combining Soybean peroxidase (SBP) attached to the SMA nanofibres and oxide nanoparticles into the polymer nanofibers, a synergic effect was observed and it was particularly marked for the Ce-doped ZnO in wastewater treatment. Supporting these materials on the SMA nanofibre mats did not compromise on the effectiveness of the materials. These supported materials offer a potentially easier and more practical application of the materials in water treatment applications.

In the present study, we investigated the effect of cerium and erbium doping of the zirconium dioxide matrix. We synthesized doped samples using hydrothermal process. The amounts of dopant used were 0.5%, 1% and 5% molar (rare earth oxide over zirconium dioxide) respectively. The samples have been studied via X-ray Diffraction measurements for the structural characterization. UV visible diffuse reflectance was used for the optical analysis, Brunauer-Emmett-Teller (BET) model for the measurement of the surface area. Finally the samples have been analysed via electron paramagnetic resonance (EPR) for the electronic characterization. Then we tested the new synthetized materials to determine their photocatalytic activity in the reaction of degradation of methylene blue performed under irradiation by diodes (LEDs) emitting exclusively visible light.

The contribution of electron magnetic resonance techniques, and in particular of CW-EPR, to the experimental research on photocatalytic phenomena is illustrated in this paper with selected examples. In the first part of the paper the role of EPR in unravelling the nature and the features of extrinsic point defects in semiconducting oxides is epitomized using the important example of the photoactive nitrogen center in various semiconducting oxides. In the second part we describe how EPR can monitor the processes that follow the initial photoinduced charge separation in photocatalysis, namely the stabilisation, migration and surface reactivity of electrons and holes. Finally, we will discuss how the role of EPR in photocatalysis is not limited to monitor phenomena occurring in the solid or at its surface but it can be extended to the investigation of the liquid phase by employing the spin trapping techniques to monitor the nature and the concentration of the reactive free radicals formed along the photocatalytic process.

The effect of cobalt doping on semiconductors materials synthesized via solution and hydrothermal methods was investigated by testing its photocatalytic efficiency on pollutants abatement. X Ray Diffraction technique was used to evaluate samples crystallographic phases allowing to identify different species due to the introduction of the dopants. Diffuse Reflectance UV–vis Spectroscopy was employed to determine the bandgap as well as the absorption corresponding to d-d transitions for cobalt doped systems. Finally, Electron Paramagnetic Resonance Spectroscopy was adopted to perform a pre-screening of the photoactivity of the prepared samples.\ud\udThe Co-doped TiO2 and ZnO materials photoactivity was assessed on phenol degradation, selected as pollutant probe, under UVA irradiation. Doping TiO2 with cobalt in low amounts (0.25% and 0.5%) prepared by hydrothermal method leads to an enhancement on phenol degradation. Also, the presence of Co-doped ZnO obtained by hydrothermal process if prepared with defined cobalt amount (0.5 or 1%) promote an increasing on phenol abatement. Ketoprofen was used to evaluate the doping effect, being the Co-doped ZnO material more efficient on ketoprofen mineralization comparing with bare material. The ketoprofen and its transformation products were easily abated and, in wastewater, they were completely eliminated within 1 h, endorsing that inserting cobalt can improve the ZnO photocatalysis efficiency for water remediation.

The interaction of oxygen with Ce-ZrO2 (Ce ions diluted in the zirconia matrix) is a key aspect for many applications of this material. In this work, for the first time, an unusual reversible interaction of the O2 molecule with the surface of this solid is reported. The joint use of electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations has allowed a full description of the reversible O2 adsorption phenomenon that involves a full electron transfer from Ce3+ centers to the adsorbed O2 forming the superoxide anion (O2â¢-). The process can be completely reversed by removing the O2 gas from the atmosphere as confirmed by the calculated values of both the adsorption energy (0.45 eV) and the activation energy (negligible) of the process. This behavior is typical of a solid oxygen carrier. However, at variance of the reported cases of molecular and solid oxygen carriers that usually form Ε1 end-on adducts, in the present case a side-on, Ε2 Ce-O2 surface complex is observed. Comparison of structural data and DFT results also indicates that Ce doping occurs in the lattice of tetragonal zirconia while this is not observed in the monoclinic phase.

The photocatalytic performance of pristine and rare earth elements (La, Ce, Pr, Er, Yb) doped zinc oxide was tested toward the abatement of a model pollutant in MilliQ water and wastewater matrices. ZnO doped with Ce, Er and particularly with Yb exhibited photoactivity higher than bare zinc oxide and the benchmark TiO2 P25, especially in wastewater matrix. Several electrochemical investigations were performed via chronopotentiometry and cyclic voltammetry aimed to shed light on the reasons why the diverse materials behaved differently. From the overall data a complex picture emerged, where there is not a single property of the materials evidently outperforming the others. Nonetheless, from the analysis of whole data a limited role of doping emerged for La and Pr, doping with Er improved the photocurrent, doping with Yb favored a better accumulation of photoelectrons, and doping with Ce promoted a faster electron transfer.

For the first time, &gamma, Al2O3 and Bio-Based Substances (BBS) hybrids (A-BBS) were prepared through a simple electrostatic interaction occurring between alumina, used as a support, and BBS (Bio-Based Substance from composted biowastes) carrying positive and negative charges, respectively. We evaluated the optimal amount of BBS to be immobilized on the support and the stability of the resulting A-BBS in order to use this novel hybrid material as an adsorbent for the removal of polar pollutants. Characterization was carried out by X-Ray Diffraction (XRD) for evaluating the crystal structure of the support, Fourier transform infrared spectroscopy (FT-IR) to evidence the presence of BBS on the hybrid material, thermogravimetric analysis (TGA) to measure the thermal stability of the hybrid materials and quantify the BBS amount immobilized on the support, N2 adsorption at 77 K for the evaluation of the surface area and porosity of the systems, Zeta potential measurements to evaluate the effect of BBS immobilization on the surface charge of the particles and choose the substrates possibly interacting with them. Firstly, we tested the adsorption capability of three samples differently coated with BBS toward cationic species considering various adsorbate/adsorbent ratio. Crystal Violet (CV) was chosen as model pollutant to compare the performance of the hybrid materials with those of other materials described in the literature. The adsorption data were modeled by Langmuir and Freundlich adsorption isotherms. Then, we studied the adsorption capability of the developed material towards molecules with different structures, for this purpose, two contaminants of emerging concerns (carbamazepine and atenolol) were tested. The results indicate that A-BBS could be applied in wastewater treatment for the removal of a significant amount of polar species. In addition, a comparison with literature data concerning CV adsorption was carried out in order to evaluate the environmental impact of synthetic routes used to prepare different adsorbents.

Objetivo: Descrever os benefícios da aromaterapia e os cosméticos orgânicos para pacientes com câncer de mama e a atuação do enfermeiro nas orientações e indicações de uso para a recuperação e tratamento. Métodos: Tratou-se de um artigo de revisão de literatura, realizou-se um levantamento nas diferentes bases de dados como: SCIELO, BVS, Google Acadêmico, LILACS, MEDLINE, revistas e sites de órgãos regulatórios, publicados entre 2005 à 2020. Resultados: Foram incluídos 27 artigos no estudo e identificadas 4 categorias distintas, sendo elas: Reações Adversas da Quimioterapia e Radioterapia no Paciente Oncológico; O Câncer de Mama e os Cosméticos; Cosméticos Orgânicos ou Biocosméticos e O Papel do enfermeiro na Recuperação de Pacientes com Câncer de Mama em Uso de Aromaterapia. Considerações finais: A aromaterapia é uma prática que faz parte das Práticas Integrativas Complementares em Saúde (PICS), ainda pouco utilizada no Brasil pelos enfermeiros, porém respaldada pelo COFEN, vem se expandindo e inserindo o enfermeiro nesse cenário, sendo fundamental no sucesso da recuperação da paciente com câncer de mama.

The role of anatase TiO2 on the performance of VOx-TiO2 is studied by in situ spectroscopies on a series of catalysts with 1.9–9.7 V at/nm2. At low coverages, VOx is preferentially located at defect sites, spreading on the main TiO2 {101} and {100} facets at intermediate coverages. Bronsted sites concentration is maximum around 6 V atoms/nm2, and EPR shows a significant amount of V4+ at intermediate VOx densities, indicating the influence of TiO2 on their reducibility. The activity is proportional to the square of the VOx density up to 5.8 V atoms/nm2. All catalysts show the same activation energy for NH3-SCR of 56.9 ± 1.0 kJ/mol in the temperature range 160−280 °C, indicating that the reaction path does not change in the studied V coverage range. The activity does not follow the observed trends for Bronsted acid sites or reducibility, and it seems that the ability to form V-pairs is the only requirement for catalytic activity.

Summary Background Rectal swabs are the most widely used surveillance technique for detecting multidrug-resistant bacteria colonizing the intestinal tract. Obtaining these samples may cause embarrassment and discomfort to patients. Prior studies indicate that perirectal swabs are as sensitive and specific as rectal swabs with greater patient acceptance. Aim To compare inguinal and rectal swabs for the detection of multidrug-resistant bacteria colonizing the intestinal tract. Methods An epidemiological, comparative, prospective, and controlled study was undertaken with 102 Brazilian patients. Inguinal and rectal swabs were collected for culture and compared. Findings Compared to rectal swabs, the sensitivity and specificity of inguinal swabs was 91.8% and 88.7%, respectively. Even when there were low colony counts from rectal samples, there were more than 100 colonies from inguinal samples. Conclusion The inguinal region can be considered an acceptable alternative for collecting surveillance cultures for multidrug-resistant bacteria colonizing the intestinal tract. The inguinal swab technique is sensitive and specific for assessing multidrug-resistant micro-organisms, less embarrassing for patients, and simple to implement in hospital practice.

Fast and simple synthetic methods for the preparation of bare and N-doped zinc oxide, involving a stirring or microwave assisted process, are proposed. All samples were characterized by XRD analysis, BET, and DRS-UV-Vis spectroscopy. The photocatalytic activity of these nanostructured oxides was investigated using phenol and 2,4-dichlorophenol as model molecules under UV-A and visible light irradiation. N-doping in ZnO nanostructures provided a significant increase in phenol and 2,4-dichlorophenol degradation rate under Vis light, leading to a degradation rate higher than that obtained with bare ZnO. The release of chlorine as chloride ions from 2,4-dichlorophenol with N-doped ZnO was faster achieved as well and complete dechlorination was reached within 2 h of irradiation (N-doped ZnO) instead of 3 h (bare ZnO).

In this paper we compare the photocatalytic activity of two semiconductors based on ZnO: ZnO/CeO2 and ZnO/Yb2O3. The two samples were prepared via hydrothermal synthesis and fully characterized by X-ray diffraction technique, diffuse reflectance Ultra Violet- Visible spectroscopy (UV-Vis), high resolution transmission electron microscopy and finally with electron paramagnetic resonance spectroscopy. The prepared materials were also tested in their photocatalytic performances both through Electron Paramagnetic Resonance (EPR) analyzing the formation of charge carriers and with the abatement of a probe molecule like phenol, in presence and in absence of scavengers.

The photochemical and photophysical properties of a defective zinc oxide prepared by precipitation have been investigated using mainly electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopy. As already reported in the literature the band gap of the oxide contains intra band gap states related to the presence of point defects (mainly cation vacancies) in the structure. The concentration and the energy levels of such defects, a fraction of them being paramagnetic, are the basis of a mechanisms of double and multiple excitations allowing visible photons with energy lower than the band gap value (hν Eg. Remarkably, some of the paramagnetic defects present in the bulk of the as prepared materials derive from excitation of VB electrons induced by ambient light illumination. The electron excitation from VB to CB has been observed upon irradiation under vacuum at 77 K with polychromatic light and applying four different filters to the emitted radiation with cut-off in the range between 400 nm and 495 nm. The process has been monitored by EPR as the photoexcitation ends up in the formation of trapped electron centers (signal at g = 1.96) and trapped hole centers (signal in the range 2.021 > g > 2.003) both clearly detected by this technique. A scheme of the energy state distribution in the band gap of the defective oxide, obtained coupling EPR and photoluminescence results, is proposed. Finally, a non-negligible fraction of the visible light generated carriers reach the surface of the nanocrystals, entailing the typical redox reactions of photocatalysis as indicated by the detection of hydroxyl radicals in solution performed by spin-trapping. For this reason, the wet chemistry prepared zinc oxide can be considered a visible light active (VLA) system.

This work aims to investigate the role of Yb dopant in the ZnO photoactivity. A new material based on ZnO doped with a small amount of Yb (1% molar) has been synthesized, characterized and tested respect to an enhancement of the photoactivity via Electron Paramagnetic Resonance spectroscopy. The prepared material has been characterized via X Ray diffraction, UV visible spectroscopy and in particular with the transmission electron microscopy. The morphological analysis with high resolution TEM allowed us to identify the formation of a new species not visible with XRD and assigned to isolated Yb2O3 nanoparticles supported on the surface of larger particles of the more abundant zinc oxide phase. The as obtained material exhibits a band gap corresponding to UV light (≈3.3 eV), but nevertheless it shows a relevant photo-activity under irradiation with photons with λ > 420 nm (visible light). This phenomenon has been investigated by means of several methods. A specific EPR-based approach allowed to monitor and quantify the charge separation following the formation of holes in the valence band (VB) of the two materials.

In the present work, the activity of Ce and Er-doped ZrO2 nanopowders for sun-driven photocatalytic water oxidation has been investigated. ZrO2 powders with tunable amounts of tetragonal, monoclinic and cubic polymorphs have been synthesized by introducing Ce and Er (from 0.5 to 10 mol % on an oxide basis) through hydrothermal method. The aim of this work is to investigate the role of rare earth (RE) ions rich of electrons (Er3+) and with entirely empty levels (Ce4+) in the ZrO2 matrix for the sun-driven photocatalytic water oxidation reaction. The samples have been characterized by means of UV-Vis spectroscopy, X-Ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectrophotometry (XPS) and transmission electronic microscopy (TEM) with energy dispersive spectroscopy (EDS). With respect to the bare ZrO2 mainly containing monoclinic (m-) phase, an increasing amount of rare-earth (RE) dopant was found to improve the specific BET surface area and to stabilize the tetragonal (t-) or cubic (c-) polymorphs of ZrO2 at room temperature. XRD data confirmed that dopants were mainly inserted in the t-ZrO2 phase. The photocatalytic O2 evolution from water under AM 1.5 G simulated sunlight illumination of the prepared samples have been correlated with their optical, structural and chemical properties. The effect of the dopant concentration on the chemical-physical and photocatalytic properties of the Er- and Ce-doped ZrO2 materials was elucidated. The samples with 5% of RE oxide were the most active, i.e., three times more than pure zirconia. Their superior photocatalytic activity was found to be mainly correlated to two factors: (i) an optimal surface concentration of RE ions of about 3.7%, which increased charge carriers separation in the photocatalysts surface due more superficial defects of the t-ZrO2 and a higher surface area, thus enhancing the reaction kinetics, (ii) a controlled amount of monoclinic vs. tetragonal (or cubic) polymorphs of zirconia with an optimum ratio of about 70/30 of t-ZrO2/m-ZrO2. Instead, the increased ability of the RE-doped ZrO2 to harvest visible light was found to have a secondary role on the photocatalytic activity of the Ce-doped ZrO2 material.

Bare ZrO2, Ce doped ZrO2 and Er doped ZrO2 samples have been prepared by a hydrothermal process and have been used as photocatalysts for 2-propanol oxidation reaction in gas solid regime. Moreover, some preliminary tests have been carried out for CO2 reduction. The samples were physico-chemically characterized and both bare and doped ZrO2 based materials resulted active for oxidation and reduction reactions by using UV and solar irradiation. The reactivity results have been correlated with the compositional, structural and morphological features of the photocatalysts.

This work reports the effect of doping zinc oxide with lanthanide ions on structural, EPR and UV visible properties. Bare and doped samples were synthesized using the simple and green hydrothermal process. Different rare earth ions (RE = La, Ce, Pr, Er and Yb) with 1% molar ratio RE/Zn were used. The samples have been studied using X Ray Diffraction, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and UV visible diffuse reflectance spectroscopy. Finally, electron paramagnetic resonance (EPR) spectroscopy, was used to assess the materials photoactivity under UV irradiation, both in solid state, to see the charge carriers’ generation and in solution, evaluating the OH• radical formation using the DMPO (5,5-Dimethyl-1-Pyrroline-N-Oxide) spin trapping technique. The results suggest that the synthesized materials could be interesting systems for the photocatalytic abatement of emerging organic persistent pollutants in wastewater treatment plants.

Palladium is an active catalyst for the decomposition of methanol to syngas, and its chemical activity is largely affected by the interaction with the supporting substrate. Nanostructured cerium oxide can establish strong electronic interactions with finely dispersed palladium nanoparticles (NPs) leading to a substantial enhancement of their catalytic performance. To study this synergistic effect and connect it to structural parameters, we deposited Pd NPs on nanostructured cerium oxide particles exposing mainly the same (100) surface, but with different nanoshape and average dimension, and we have investigated their activity toward the methanol decomposition reaction. A systematic comparison of photoemission measurements taken at every step of the catalytic cycle allowed us to identify the most important factors that control the redox properties of the Pd/CeO2 systems and therefore the overall catalytic activity. Capitalizing on this knowledge it was possible to synthesize synergistic nanocatalysts with ...

The synthesis of a mixed CeO2–ZnO oxide results in a photocatalyst active under visible light. The characterization of the new material shows that Ce does not enter as a dopant in ZnO but rather forms isolated CeO2 nanoparticles supported on the surface of larger particles of the more abundant zinc oxide phase. The as obtained material exhibits a band gap corresponding to UV light (∼3.3 eV), but nevertheless. it shows a relevant photoactivity under irradiation with photons with λ > 420 nm (visible light). The working hypothesis is that visible light irradiation leads to a charge separation and stabilization of a fraction of the carriers connected with the formation of the CeO2/ZnO interface. This phenomenon has been investigated by means of several methods. A specific EPR-based approach allowed to monitor and quantify the charge separation following the formation of holes in the valence band (VB) of the two materials. More complex is detecting the nature of the excited electrons, as this involves the formation of EPR invisible Ce3+ ions by trapping the electrons into localized 4f states of Ce ions at the interface between the two oxides. DFT calculations provide a rational for some of the observed phenomena and a basis for the discussion of the band alignment of the two systems as a consequence of the formation of a heterojunction. The theoretical results show that indeed electrons can be excited at the interface from the VB of the two oxides into the Ce 4f states with photons of 2.3 eV, thus justifying the occurrence of a visible-light activity despite the higher band gap of the two materials.