An overview of studies on the highly dispersed uranium oxide species occluded within mesoporous MCM-41 and MCM-48 host materials

Structure Sensitivity of Nano-structured CdS/SBA-15 Containing Au and Pt Co-catalysts for the Photocatalytic Splitting of Water

“…With a view to overcome these constraints, concerted efforts have been devoted during last few years to prepare various nano-structured semiconducting materials, so as to improve their surface-to-volume ratio and hence the reaction efficiency, as is reviewed in several articles [2,3]. Another approach has been to confine these nano-particles in certain porous silicate matrices in order to ensure easier catalyst recovery after completion of the reaction and at the same time to provide a hydrophobic environment to catalyst particles [4][5][6][7][8][9][10][11][12]. We have reported recently that the CdS nanocrystallites anchored over certain water-repellent polymeric surface not only exhibit a high catalytic activity for visible light-driven hydrogen production from water splitting, they also maintain a significantly long active life because of the hydrophobic nature of the support [13].…”

Chemical State of Complex Uranium Oxides

“…Uranium oxides are not only used in power plants but also, e.g., catalysis applications. The use of U 3 O 8 was encouraged in U 3 O 8 /SiO 2 catalysts which can efficiently destroy a range of hydrocarbons and chlorine-containing pollutants [12], because of the believed availability of two distinct oxidation states U(VI) and U(IV) and easy conversion between them [13]. In all applications a direct observation of the U chemical state is of paramount importance.The existence of a variety of stochiometric and non-stochiometric U oxides with their complex physical and chemical properties makes them demanding systems to characterize.…”

“…One heavily debated topic was the observation of small U-O distances in the U 4 O 9 compound, which are characteristic for U(VI) compounds [20]. This was questioned by other theoretical and experimental works [18,21] that assumed that U 4 O 9 is a mixture of U(IV) and U(V).A number of studies to determine the U oxidation state for these systems have been reported using non-destructive spectroscopic methods: X-ray photoelectron spectroscopy (XPS) [13,22], electron energy-loss spectroscopy (EELS) [23], X-ray absorption near edge structure (XANES) [20,23,24] resonant inelastic soft X-ray scattering (RIXS) [25] and laserinduced fluorescence (LIF) spectroscopy [26]. Spectroscopic techniques often use the shifts in energy position of the main absorption/emission transitions in order to determine the U valence state.…”

“…A number of studies to determine the U oxidation state for these systems have been reported using non-destructive spectroscopic methods: X-ray photoelectron spectroscopy (XPS) [13,22], electron energy-loss spectroscopy (EELS) [23], X-ray absorption near edge structure (XANES) [20,23,24] resonant inelastic soft X-ray scattering (RIXS) [25] and laserinduced fluorescence (LIF) spectroscopy [26]. Spectroscopic techniques often use the shifts in energy position of the main absorption/emission transitions in order to determine the U valence state.…”

Preparation of nickel-mesoporous materials and their application to the hydrodechlorination of chlorinated organic compounds

“…Ordered mesoporous materials have been widely employed in many fields of science and engineering, including separation [18] and catalysis [19][20][21]. The mesoporosity that can be easily controlled by adjusting the preparation conditions of mesoporous materials has many advantages in catalysis.…”