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A pesquisa científica é uma parte importantíssima no desenvolvimento de um aluno. Através dela você pode aprender um contexto mais amplo da área, acrescentar pontos que não conseguem ser explicados numa sala de aula convencional, dá mais riqueza e versatilidades aos temas já conhecidos. Para uma universidade carregar o título de universidade, ela precisa ter incentivo à pesquisa científica. Ou seja, é de interesse da toda e qualquer instituição de ensino superior que esse campo de pesquisa possa ser explorado por seus alunos. Esse é o segredo que este livro mostra para você. Então um lugar que incentive os alunos a ter esse contato extraclasse com assuntos do seu interesse, que tenham laboratórios modernos e bem equipados e que sejam referência nesse assunto podem se mostrar uma excelente maneira de te ajudar numa escolha de faculdade. Enfim, aliar a pesquisa científica com a prática dentro de um ambiente universitário, é excencial.

International audience; Methane valorization is one of the main challenges in the modern chemical industry. However, existing processes require high reaction temperatures. The alternative photocatalytic routes for methane valorization at ambient conditions would be highly attractive. Today, photovoltaic (PV) generation of electricity is one of the main sources of renewable energy. PV absorbers could be excellent candidates for photochemical applications. Herein, we report selective methane photocatalytic oxidation at ambient conditions into CO and H2 by conventional Cu(In,Ga)Se2 (CIGS) absorbers used in solar cells. A thin film of CIGS coated over Mo exhibits exceptional performance in methane partial oxidation to CO and H2 with a stable CO productivity of 2.4 mmol per g of CIGS and a selectivity to CO of over 80 %. The reaction proceeds via the facile dissociation of methane into disordered carbon and hydrogen over CIGS surface with subsequent regeneration of the surface by partial oxidation of carbon into CO.

Future long-term space missions beyond Low Earth Orbit (e.g., to Mars) depend on the development of bioregenerative life support systems able to produce food crops based on in situ resource utilization. Mars regolith potentially contains most of the essential nutrients for plant growth, except for organic matter (OM). Several strategies and treatments can be applied to improve nutrient deficiency of simulants and enhance their performance as plant growth substrates. Although Mars regolith simulants have been characterized by mineralogical, physico-chemical and hydraulic properties, no data are available to date in the scientific literature about the stabilization of exogeneous OM by minerals, including iron (Fe) oxides, over time.This study aims at understanding the mineral transformation and OM turnover in the early stages of terraforming. The Mojave Mars Simulant MMS-1, alone (R100) and with a commercial compost 70:30 v:v (R70C30), was compared to a fluvial sand, alone and with compost (S100 and S70C30). Potato was grown on these substrates for 99 days in greenhouse. Samples were fractionated, obtaining particulate OM (POM) and mineral associated OM (MAOM), andcharacterized for total nitrogen and organic carbon (OC), total element concentration (ICP-OES) and by Fe K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS).In the whole medium, OC increased in S70C30 (10×) and R70C30 (25×). As expected, most of the OC accumulated in the POM fraction of both growing media (10× in S70C30 and 20× in R70C30), while OC in the MAOM was 3-times higher in R70C30 than in S70C30. Chlorite, smectite and goethite were the main Fe species in S100, according to XANES, while Fe(III)-OM was found in both fractions of S70C30. Moreover, according to EXAFS, hematite occurred in POM, whereas goethite in MAOM. XANES revealed the occurrence of smectite, maghemite and ferrihydrite in R100, and of nontronite and hematite in the MAOM and POM, respectively.Revealing Fe species involved in the formation of organo-mineral interactions will help to identify the main critical aspects and future challenges related to sustainable space farming improving the in-situ use of Martian resources.

International audience; SERS evolution recorded over a drop-coated coffee-ring pattern of citrate-capped gold colloids was investigated as a function of time under low-specific laser power. Spectral changes caused by plasmon-induced reaction could not be detected, but a long-term transient original spectral profile showing additional lines was observed. We performed deep qualitative and quantitative SERS intensity variation analysis based on the complementary use of extreme deviation and cross-correlation statistics, which provided further insights on the behavior of citrate-capping layers of gold nanoparticles upon laser illumination. More precisely, the cross-correlation analysis made possible to follow the so-called individual events denoting particular resonance structures, in which groups of modes were assigned to an evolution of citrate coordination on gold surface driven by photo-activation. As a consequence, the detection limit was increased and new lines were related to the presence of a very low amount of dicarboxy-acetone (DCA), which was already present in the system.

Negative thermal expansion (NTE) is an abnormal thermophysical phenomenon. Although NTE has been discovered in a growing number of materials, it is difficult to achieve both strong NTE and a wide o...

High-entropy oxides based on transition metals, such as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation into TM-HEO-based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed a high specific capacity exceeding 600 mAh g-1 at 0.1 C and Coulombic efficiency very close to unity. The combination of functional and advanced spectroscopic studies revealed complex charging mechanisms, developing through the reduction of transition-metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and incomplete, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account for the observed cycling behavior of the TM-HEO-based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ∼60% of lithiation capacity, so proving the beneficial role of the configuration entropy in enhancing the stability of the HEO rock-salt structure during the redox phenomena.

Photoelectrochemical (PEC) water splitting devices using semiconductors and electrocatalysts rely on heterogeneous interfaces that drive charge separation, thus determining potential gradients that...

A 3-m thick sediment was found in a limestone mine located in the Apulia region (south of Italy), at a depth of 25-30 m from the current ground level. Samples from 5 layers were investigated by X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) at the iron (Fe) K-edge, paired with Raman spectroscopy (RS) and thermal analysis.The pedosediment record under investigation represents a peculiar stratigraphic series showing complex features related to the Fe dynamic.From a technical point of view, the challenges of phase identification in Fe oxides are many, but the application of multiple techniques provides sufficient evidence for the identification and discrimination of Fe phases. The combination of Fe XANES and EXAFS allowed to get information on the Fe speciation and its local structure. In detail, ferrihydrite is the most abundant Fe species, followed by goethite and minor amounts of hematite. Ferrihydrite content decreases with depth, where goethite and hematite occur. The presence of ferrihydrite, only detected by Linear Combination Fitting (LCF) on the first-derivative XANES spectra and on the EXAFS spectra, suggests that redox cycling of Fe occurred in these sediments. In addition, higher contents in Fe(III) complexed by organic matter is found in the top and deepest layer.Generally speaking, RS and thermal analysis might present a promising tool to unravel some mineralogical components such as calcite, goethite and some Mn-oxides. Unlike for the identification of some Fe-bearing minerals like ferrihydrite, RS seems to be not well suited and this aspect require further investigations.Definitely, this study confirms that each layer has preserved the distinct features that relate to its time of deposition. We underline how a multidisciplinary approach is strongly required to obtain reliable records when peculiar environments like karst pedosequences are investigated.

O presente trabalho tem como objetivo analisar o processo de significação do conceito de energia, a partir da aplicação de uma sequência didática pautada na perspectiva Ciência, Tecnologia e Sociedade (CTS) e na Teoria dos Perfis Conceituais. Tal sequência foi planejada com base nas ideias de Mehéut, assumindo como princípio os quatro componentes básicos, a saber: professor, aluno, conhecimento científico e mundo real (ou material), e as duas dimensões, pedagógica e epistemológica. A pesquisa, recorte da dissertação de mestrado, é de natureza qualitativa e foi desenvolvida em uma escola integral da rede pública de ensino do estado de Pernambuco, localizada em Maranguape I, Paulista, com a participação dos estudantes do 2° ano do Ensino Médio. A partir dos dados coletados em uma das etapas, debate sobre a Questão sociocientífica (QSC) apresentada, analisamos as relações CTS e emergências das zonas do perfil conceitual de energia. Os resultados revelam a emergência de várias zonas do perfil conceitual, que guardam fortes relações com o contexto das atividades e convergem com as discussões propostas pela perspectiva CTS. Ainda, concluímos que a proposta possibilita a ampliação das discussões sobre o conceito de energia, considerando diversos contextos e os modos de pensar de maior valor pragmático.

A systematic structural study of Ni in the Ni/ZSM-5 materials is presented, which is beneficial for any further investigation of the catalytic activities of Ni/ZSM-5 and other metal-modified bifunctional catalysts.

Aim: The aim of this study was to evaluate the feasibility of adequacy, accuracy, and safety of ultrasound-guided tru-cut biopsy in managing malignant and benign abdominopelvic masses in a selected population and critically discuss some issues in different situations, which deserve some reflections on those practices. Materials and Methods: This is a retrospective study involving 42 patients who underwent transvaginal or transabdominal tru-cut biopsy between August 2017 and November 2021. The inclusion criteria were poor health status or primary inoperable advanced tumor, suspicion of recurrence or metastasis to the ovaries or peritoneum in gynecological and non-gynecological pelvic malignancies. Tissue samples were considered adequate if it was possible to determine the origin of the tumor, and immunohistochemistry could be performed. Diagnostic accuracy was assessed considering the agreement between tru-cut biopsy histology and final postoperative histology. Results: It total, 44 biopsies were obtained from 42 patients (2 patients had repeat biopsies). The pathologist considered all pathological samples adequate (adequacy 100%). The final histology was consistent with tru-cut biopsy diagnosis in all but 2 cases (diagnostic accuracy 88.2%). If we consider only the cases that have carried out at least two diagnostic samples, accuracy rose to 94.1%. Pathological examinations from tru-cut samples showed 2 benign lesions (4.8%) and 40 malignant tumors (95.2%), divided into 19 advanced primary inoperable ovarian cancers, 7 primary advanced cervical cancers, 4 recurrent endometrial cancers, 3 recurrent cervical cancers, 3 recurrent ovarian cancers, 1 case of primitive peritoneal malignancy (leiomyosarcoma), and 3 non-gynecological cancers with a strong suspicion of metastases at ultrasound (2 cases of ovarian, colorectal cancer metastasis, and 1 case of pelvic site type B lymphoma metastasis). However, one case of minor complication related to the procedure was reported but not significant. Conclusions: The diagnostic adequacy, accuracy of the tru-cut biopsy, and safety were high. Pathological samples are representative of the disease and suitable for histological and immunohistochemical analysis.

The satisfactory rationalization of complex reactive pathways in solution chemistry may greatly benefit from the combined use of advanced experimental and theoretical complementary methods of analysis. In this work, we combine X-Ray Absorption and 1 H-NMR spectroscopies with state-of-the-art Multivariate Curve Resolution and theoretical analyses to gain a comprehensive view on a prototypical reaction involving the variation of the oxidation state and local structure environment of a selected metal ion coordinated by organic ligands. Specifically, we investigate the 2-cyano-2-phenylpropanoic acid reduction of the octahedral complex established by the Cu 2+ ion with terpyridine to the tetrahedral complex formed by Cu + and neocuproine. Through our interdisciplinary approach we gain insights into the nature, concentration time evolution and structures of the key metal (XAS measurements) and organic ( 1 H NMR measurements) species under reaction. We believe our method may prove to be useful in the toolbox necessary to understand the mechanisms of reactive processes of interest in solution.

Negative thermal expansion (NTE) behaviors have been observed in various types of compounds. The achievement in the merits of promising low-cost and facile NTE oxides remains challenging. In the pr...

We have investigated the molecular and electronic structure of a TiO2-supported oxomolybdate phase upon reduction under methanol or dihydrogen atmosphere. In situ Mo K-edge X-ray absorption spectro...

Over the last few decades, MOSFET architectures have evolved from planar to 3D structures (FinFET and, more recently, gate-all-around and Forksheet devices) to improve the channel control at very scaled dimensions. In this framework, highly doped conformal Si1-xGex epitaxial films are used for source/drain (S/D) regions in pMOS devices to form ohmic metal-semiconductor contacts with low specific contact resistivities (ρc). Boron is the main p-type dopant in Si1-xGex thanks to its high active concentration (~ 1×1021 at./cm3) for Ge concentrations of ~ 50 at.% [1]. For higher Ge/Si ratios, gallium is considered a promising doping element due to its higher solid solubility in Ge compared with boron. However, a strong Ga surface segregation is reported to occur during the epitaxy of in situ doped Si1-xGex, leading to a Ga-rich second phase at the epilayer surface [2]. In films grown at temperatures ≥ 450°C, the Ga surface segregation limits the bulk Ga concentration ([Ga]chem) to 1×1018 at./cm3 [3]. This low doping level results in inferior electrical properties for current MOSFET applications. Models in the literature [4] indicate that, at sufficiently low temperature, dopant segregation is limited by surface kinetic mechanisms. Thus, the segregation ratio could be controlled by changing the process temperature. Based on this approach, low temperature, Si2H6 + Ge2H6 based processes with improved Ga incorporation were developed [5]. In this contribution, we report on novel in situ Ga doped Si1-xGex epitaxial layers grown at temperatures ≤ 400°C. Using a HCl surface clean, necessary to avoid the SIMS Ga decay from the surface which can mask the real concentration profile [3], Ga box-shaped profiles with concentrations above 1×1020 at./cm3 are found (Fig. 1). Two growth temperatures are compared: 400°C and 350°C. For each temperature, variable Ga precursor (tri-tert-butyl gallium) flows (fTTBGa) were used. A reduction in the growth temperature enhances the Ga incorporation, as evidenced from the two SEM morphology inspections displayed in Fig. 1. Here, two samples with a similar bulk [Ga]chem of ~ 6 ×1019 at./cm3, as measured by SIMS, exhibit either a clustered or smooth surface depending on the deposition temperature applied. This improved Ga incorporation allows for systematic studies of in situ Ga doping on the structural and electrical properties of Si1-xGex. In both series of samples, the layer resistivities (ρ) follow a similar trend, characterized by a steep decrease at smaller fTTBGa and a plateau for higher flows (Fig. 2). The lowest ρ values are found for the layers grown at 350°C. This denotes that different saturation levels in the active Ga concentration ([Ga]act) exist for the process conditions used here. In a similar way to what is typically observed for B doping, an increase in the Ga doping level causes a boost in epilayer growth rate. This growth rate trend saturates simultaneously with ρ, suggesting that the phenomenon is linked to the level of incorporated substitutional Ga atoms. In addition, the resulting Ge concentrations of the Si1-xGex layers are found to increase with Ga concentration. From HR-XRD analysis, strain-relaxation is also found to progressively increase with the TTBGa flow and so the incorporated Ga may not be fully active. For this reason, X-ray absorption fine structure spectra (XAFS) were acquired at the Ga K-edge on Si0.4Ge0.6:Ga and Ge:Ga epilayers with the results obtained reported in Fig.3. Based on comparative analysis of the first coordination Ga shell with DFT simulation results, Ga dopants appear to be placed in substitutional positions for both materials. Furthermore, a shorter nearest-neighbors distance is measured for Ga in Si0.4Ge0.6 compared to Ge, indicating a difference in the local strain associated to the dopant for the two considered matrixes. [1] R. Loo et al., “Processing Technologies for Advanced Ge Devices,” ECS J. Solid State Sci. Technol., vol. 6, no. 1, pp. P14–P20, 2017. [2] J. Margetis et al., “Epitaxial Growth of Ga-doped SiGe for Reduction of Contact Resistance in finFET Source/Drain Materials,” ECS Trans., vol. 93, no. 1, pp. 7–10, 2019. [3] G. Rengo et al., “B and Ga Co-Doped Si1−xGex for p-Type Source/Drain Contacts,” ECS J. Solid State Sci. Technol., vol. 11, no. 2, 024008, 2022. [4] C. B. Arnold and M. J. Aziz, “Unified kinetic model of dopant segregation during vapor-phase growth,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 72, no. 19, 195419, 2005. [5] A. Y. Hikavyy et al., “Cutting-Edge Epitaxial Processes for Sub 3 Nm Technology Nodes: Application to Nanosheet Stacks and Epitaxial Wrap-Around Contacts,” ECS Trans., vol. 104, no. 4, pp. 139–146, Oct. 2021. Figure 1

Chemical substitution is an effective method to control the thermal expansion properties in solid solutions. In this work, a series of solid solutions Cu2-xZnxP2O7(0 ≤ x ≤ 2) were synthesized by solid state methods. The thermal expansion in Cu2-xZnxP2O7 is tuned from strong negative thermal expansion (αv ~ -33.5×10-6 K-1, 100 - 375K) to near zero thermal expansion (αv ~ -2.78×10-6 K-1, 100 - 225K), and then to positive thermal expansion gradually with increasing content of Zn2+ substitution. The direct experiment results reveal that the Zn2+ substitution diminishes the rigidity of Cu/Zn-O and P-O bonds and the transverse vibrations of O atoms arousing negative thermal expansion. The present work realizes the control of thermal expansion from negative to near zero, and then to positive in the Cu2P2O7 system.

Paddy soils experience long-term redox alternations affecting the interactions between the biogeochemical cycling of iron (Fe) and carbon (C). Although the higher soil organic matter (SOM) accumulation rates in paddy topsoils with respect to non-paddy soils is generally assumed to be due to limited mineralization under anoxic soil conditions resulting from frequent field flooding, there is growing evidence questioning this assumption. Moreover, differences in particle aggregation and SOM turnover are likely to both affect and be affected by the trajectory of Fe mineral evolution/crystallinity with redox fluctuations. We hypothesized that redox cycling in paddy soils will affect the particle aggregation, the distribution and mineralogy Fe (hydr)oxides between aggregate size fractions, and consequently the mechanisms of SOM stabilization. In particular, we expect finer aggregate and particle size classes to have a higher proportion of short-range ordered (SRO) Fe oxides with respect to larger aggregates under paddy management, compared to non-paddy management, and that paddy management can result in lower amounts of Fe(hydr)oxides in the topsoil with respect to non-paddy soils. We tested these hypotheses by evaluating mineralogical changes, and the distribution of Fe species and organic C between different aggregate and particle-size fractions in topsoil (eluvial) and subsoil (illuvial) horizons of soils under long-term paddy (P) horizons (Arp1, Arp2, Arpd, Brd1, Brd2) and non-paddy (NP) horizons (Ap1, Ap2, Bgw) in NW Italy. Soil aggregates (microaggregates: μm, free silt: (53-2 μm), free clay: μm, and, after sonication, fine sand, silt and clay within microaggregates) have been obtained frombulk soils using an aggregate and particle size physical fractionation method. After fractionation, Fe phases were evaluated by selective extraction procedures, X-ray diffraction (XRD) and Fe K-edge extended X-ray fine structure (Fe EXAFS) spectroscopy (Elettra XAFS beamline). Our results indicate: (1) a depletion in the contents of ferrihydrite in the P topsoil horizons with respect to NP, though redox cycling favoured an increase in ferrihydrite in the P subsoil, possibly due to Fe(II) translocation from topsoil to subsoil, with consequent ferrihydrite precipitation and aggregates formation; (2) more crystalline Fe mineral phases were associated with intra-aggregate clay fraction in the P topsoil. In the clay fraction in the Brd2 subsoil horizon magnetite was observed. In the NP soil the illuvial horizons were not characterized by a significant increase in ferrihydrite. Our hypothesis that finer aggregate and particle size classes have a higher proportion of SRO Fe oxides with respect to larger aggregates under P management, with respect to NP management, was confirmed; (3) more organic C was associated with the fine fraction in P with respect to NP suggesting that redox cycling enhances the chemical stabilization of mineral-associated SOM. These findings focused on localized Fe dynamics and biogeochemical coupling with SOM, suggesting that redox-driven changes in aggregate-size classes distribution were also linked to the differences in organic C and Fe stocks in these two agro-ecosystems.

Paddy soils experience long-term redox alternations affecting the interactions between the biogeochemical cycling of iron (Fe) and carbon (C). Differences in particle aggregation and soil organic matter (SOM) turnover are likely to both affect and be affected by the trajectory of Fe mineral evolution/crystallinity with redox fluctuations. We hypothesized that the legacy effects of redox cycling under paddy management affects particle aggregation, the distribution and mineralogy of Fe (hydr)oxides between particle-size fractions, and the interaction with SOM stabilization. Moreover, we expected underlying processes to be different in paddy eluvial and illuvial horizons, particularly due to the different inputs and redox conditions these horizons experience. To test these hypotheses, we evaluated the distribution of Fe species and organic C between different aggregate and particle-size fractions in topsoil (eluvial) and subsoil (illuvial) horizons of soils under long-term paddy and non-paddy management in NW Italy, as well as mineralogical changes in Fe phases by Fe K-edge Extended X-ray Adsorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) spectroscopy. Our findings indicate that although paddy topsoils are depleted in hydrous Fe oxides with respect to non-paddy soils, they can stabilize important amounts of C through mineral associations, particularly with finer particle-size fractions rich in less crystalline Fe phases. We also show that redox cycling can influence microaggregate stability and consequently the distribution of Fe phases and OC between intra and inter-microaggregate fractions. On the other hand, illuvial horizons under paddy management were enriched in short-range ordered hydrous Fe oxides and this contributed to enhanced microaggregate formation and C stabilization with respect to non-paddy subsoils.

Chemical substitution is an effective strategy to control the thermal expansion properties in solid solutions. In this work, a series of solid solutions Cu2-xZnxP2O7 (0 ≤ x ≤ 2) were synthesized by solid state reaction methods. The thermal expansion in Cu2-xZnxP2O7 is tuned from strong negative thermal expansion (αv ∼ -33.5×10−6 K−1, 100 - 375K) to near zero thermal expansion (αv ∼ -2.78×10−6 K−1, 100 - 225K), and then to positive thermal expansion gradually with increasing content of Zn2+ substitution. The direct experiment results reveal that the Zn2+ substitution diminishes the rigidity of Cu/Zn-O and P-O bonds and the transverse vibrations of O atoms arousing negative thermal expansion. The present work achieves the regulation of thermal expansion from negative to near zero and finally to positive in the Cu2P2O7 system.

International audience; The electronic and local structural properties of single crystals in the ground state (GS) of the photo-switchable compound Na2[Fe(CN)5NO]•2H2O (sodium nitroprussiate, SNP) have been investigated by X-ray Absorption Fine Structure Spectroscopy (XAFS) and FEFF simulations. In SNP, the XANES (X-ray Absorption Near Edge Structure) pre-edge region presents three distinct peaks with different intensities depending on the crystal axis orientation with respect to the polarization direction of the X-ray beam. The peaks correspond to a combination of 1s to 4p and 1s to 3d transitions with possibly mixed dipole and quadrupole character. The EXAFS fitting reveals, as expected, a biased structure according to the relative position of the crystal with respect to the beam polarization and the fittings are in accordance to theoretical values. The best fitted model has a large contribution from multi-scattering paths, which clarifies the interpretation of the actual peak contributions on the Fourier Transformed signal.

Gold nanoparticles (AuNP) exhibit particular plasmonic properties when stimulated by visible light, which makes them a promising tool to many applications in sensor technology and biomedical applications, especially when associated to sulfur-based compounds. Sulfur species form a great variety of self-assembled structures that cap AuNP and this interaction rules the optical and plasmonic properties of the system. Here, we report the behavior of citrate-stabilized gold nanospheres in two distinct sulfur colloidal solutions, namely, thiocyanate and sulfide ionic solutions. Citrate-capped gold nanospheres were characterized using ultraviolet–visible (UV-Vis) absorption, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). In the presence of sulfur species, we have observed the formation of NP clusters and chain-like structures, giving rise to surface-enhanced effects. Surface-enhanced Raman spectroscopy (SERS) pointed to a modification in citrate vibrational modes, which suggests substitution of citrate by either thiocyanate or sulfide ions with distinct dynamics, as showed by in situ fluorescence. Moreover, we report the emergence of surface-enhanced infrared absorption (SEIRA) effect, which corroborates SERS conclusions. Further, SEIRA shows a great potential as a tool for specification of sulfur compounds in colloidal solutions, which is particularly useful when dealing with sensor technology.

Negative thermal expansion (NTE) behaviors have been observed in various types of compounds. The achievement in the merits of promising low-cost and facile NTE oxides remains challenging. In the present work, a simple and low-cost Cu

High entropy oxides based on transition metals, as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries, due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation on TM-HEO based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed high specific capacity exceeding 600 mAh g-1 at C/10 and Coulombic efficiency very close to unit. The combination of functional and advanced spectroscopic study revealed complex charging mechanisms, developing through an initial Li intercalation reaction during the first charging cycle, followed by the reduction of transition metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and not completed, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account the observed cycling behavior of the TM-HEO based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ~ 60% of lithiation delivered capacity, so proving the beneficial role of the configuration entropy to enhance the stability of the HEO rock-salt structure during the redox phenomena.

Titania-based hydrodesulfurization catalysts were prepared by using a one-pot sol–gel method with the titanium peroxo complex as titanium precursor and molybdenum and cobalt precursors dissolved in the aqueous hydrogen peroxide solution used during synthesis. Catalysts with MoO3 loadings varying from 5 to 40 wt % and a Co/Mo atomic ratio of 0.5 were prepared. Solids with molybdenum loadings below 20 wt % MoO3 demonstrated poor hydrodesulfurization activity for the model compound thiophene. This was attributed to the presence of a large amount of embedded cobalt and molybdenum species in the titania matrix. A significant increase in the catalytic activity was observed for solids containing 20 and 25 wt % of MoO3 on which active species appeared to be accessible on the titania surface. Furthermore, the highest conversion obtained on these sol–gel solids was superior to the highest conversion obtained on reference catalysts prepared through the impregnation of ammonium heptamolybdate and cobalt nitrate on commercial titania.