Reactivity of shape-controlled crystals and metadynamics simulations locate the weak spots of alumina in water

International audienceThe kinetic stability of any material in water relies on the presence of surface weak spots responsible for chemical weathering by hydrolysis. Being able to identify the atomistic nature of these sites and the first steps of transformation is therefore critical to master the decomposition processes. This is the challenge that we tackle here: combining experimental and modeling studies we investigate the stability of alumina in water. Exploring the reactivity of shape-controlled crystals, we identify experimentally a specific facet as the location of the weak spots. Using biased ab initio molecular dynamics, we recognize this weak spot as a surface exposed tetra-coordinated Al atom and further provide a detailed mechanism of the first steps of hydrolysis. This understanding is of great importance to heterogeneous catalysis where alumina is a major support. Furthermore, it paves the way to atomistic understanding of interfacial reactions, at the crossroad of a variety of fields of research

the influence of edge state of mos2 o the photo(electro)catalytic performance

SSCI-VIDE+ECI2D+EPU:CGE:PAFInternational audienceThis study aimed to define key preparation and treatment parameters determining the hydrogen evolution reaction (HER) performance of molybdenum sulfide-based photocatalysts. Amorphous and nanocrystalline molybdenum sulfide catalysts supported on titania have been studied in photocatalytic and electrochemical hydrogen production. Titania polymorph plays a crusial role: high-surface area anatase PC500 and anatase-rutile Degussa P25 show high HER performance, whereas rutile nanorods demonstrate poor activity. Impregnation and solution deposition techniques have been compared. Solution deposition gives superior activity, with a maximum for 0.5 % Mo weight loading, even if the dispersion of MoS2 phase is better for impregnated systems. Therefore, the abundance of MoS2 edge sites is of secondary importance, whereas the electron hopping from the semiconductor to the co-catalyst seems to be the limiting step. In order to study the influence of treatment conditions, the solids were reduced under H2 of treated in pure H2S. The role of edge S22- groups, slabs length and stacking has been discussed. There is no tangible correlation of the photocatalytic HER activity and thiophene HDS activity. In contrast, electrocatalytic HER correlates with thiophene HDS as both are privileged by the presence of highly dispersed and short MoS2 slabs

On the photocatalytic and electrocatalytic hydrogen evolution performance of molybdenum sulfide supported on TiO2

SSCI-VIDE+ECI2D+EPU:CGE:PAFInternational audienceHydrogen evolution reactio

the influence of edge state of mos2 o the photo(electro)catalytic performance

SSCI-VIDE+ECI2D+EPU:CGE:PAFInternational audienceThis study aimed to define key preparation and treatment parameters determining the hydrogen evolution reaction (HER) performance of molybdenum sulfide-based photocatalysts. Amorphous and nanocrystalline molybdenum sulfide catalysts supported on titania have been studied in photocatalytic and electrochemical hydrogen production. Titania polymorph plays a crusial role: high-surface area anatase PC500 and anatase-rutile Degussa P25 show high HER performance, whereas rutile nanorods demonstrate poor activity. Impregnation and solution deposition techniques have been compared. Solution deposition gives superior activity, with a maximum for 0.5 % Mo weight loading, even if the dispersion of MoS2 phase is better for impregnated systems. Therefore, the abundance of MoS2 edge sites is of secondary importance, whereas the electron hopping from the semiconductor to the co-catalyst seems to be the limiting step. In order to study the influence of treatment conditions, the solids were reduced under H2 of treated in pure H2S. The role of edge S22- groups, slabs length and stacking has been discussed. There is no tangible correlation of the photocatalytic HER activity and thiophene HDS activity. In contrast, electrocatalytic HER correlates with thiophene HDS as both are privileged by the presence of highly dispersed and short MoS2 slabs

Innovative way to stabilize catalysts for biomass transformation methods

SSCI-VIDE+CDFA:ING+EGR:ATU:MBEInternational audienceNon

Innovative way to stabilize catalysts for biomass transformation methods

SSCI-VIDE+CDFA:ING+EGR:ATU:MBEInternational audienceNon

Innovative way to stabilize alumina for biomass transformation reactions

SSCI-VIDE+CDFA:ING+EGR:ATU:MBENational audienceNon

30 ans de suivi de la qualité physico-chimique et microbiologique de l’eau du Rhône en Savoie GRUTTEE

International audienc

La contamination historique aux PCB et aux HAP du bassin versant du lac du Bourget : quel impact sur la ressource en eau ?

International audienc

Comprehensive plasma steroidomics reveals subtle alterations of systemic steroid profile in patients at different stages of prostate cancer disease

The steroid submetabolome, or steroidome, is of particular interest in prostate cancer (PCa) as the dependence of PCa growth on androgens is well known and has been routinely exploited in treatment for decades. Nevertheless, the community is still far from a comprehensive understanding of steroid involvement in PCa both at the tissue and at systemic level. In this study we used liquid chromatography/high resolution mass spectrometry (LC/HRMS) backed by a dynamic retention time database DynaSTI to obtain a readout on circulating steroids in a cohort reflecting a progression of the PCa. Hence, 60 relevant compounds were annotated in the resulting LC/HRMS data, including 22 unknown steroid isomers therein. Principal component analysis revealed only subtle alterations of the systemic steroidome in the study groups. Next, a supervised approach allowed for a differentiation between the healthy state and any of the stages of the disease. Subsequent clustering of steroid metabolites revealed two groups responsible for this outcome: one consisted primarily of the androgens, whereas another contained corticosterone and its metabolites. The androgen data supported the currently established involvement of a hypothalamic-pituitary–gonadal axis in the development of PCa, whereas biological role of corticosterone remained elusive. On top of that, current results suggested a need for improvement in the dynamic range of the analytical methods to better understand the role of low abundant steroids, as the analysis revealed an involvement of estrogen metabolites. In particular, 2-hydroxyestradiol-3-methylether, one of the compounds present in the disease phenotype, was annotated and reported for the first time in men