01927nas a2200145   4500008004100000022001400041245013900055210006900194260000900263300001400272490000600286520134600292100002401638856011901662       2019                        eng d  a2398-490200aEnhanced light harvesting and charge separation over wormhole mesoporous TiO2-X nanocrystallites towards efficient hydrogen generation0 aEnhanced light harvesting and charge separation over wormhole me  cMAY   a1191-12000 v33 a<p>Here meso-TiO2-X materials with combined visible light absorption, high surface area, an anatase-rutile heterojunction, and electrically interconnected nanocrystallites in a wormhole mesoporous framework are achieved. Meso-TiO2-X materials were prepared by solution combustion synthesis (SCS), followed by hydrogenation at higher temperatures. The materials are thoroughly characterised by various physicochemical techniques. A small band gap (2.8 eV), type IV-H-2 mesoporosity with a biphasic heterojunction, and small pore depths (10 nm) in a wormhole mesoporous framework are observed with 35AP. Photocatalytic water splitting for hydrogen production and photocurrent generation were carried out with meso-TiO2-X materials under simulated sunlight. A six-fold increase in activity under AM 1.5G irradiation was observed, which is attributed to the generated mid-gap states which lead to band gap reduction, improved optical absorption in the visible and infrared light region resulting in higher charge carrier density. The presence of a biphasic heterojunction between the (1 0 1) anatase and (1 1 0) rutile facets assists in effective charge separation. A low charge diffusional constraint associated with wormhole mesoporosity helps in facile charge transport to the surface for improved charge utilisation in redox reactions.</p>
1 aNegi, Sanjay, Singh  uhttps://library.ncl.res.in/content/enhanced-light-harvesting-and-charge-separation-over-wormhole-mesoporous-tio2-x01852nas a2200217   4500008004100000022001400041245013200055210006900187260000800256490000800264520105300272653001601325653002401341653003601365653003001401653001801431100002401449700002001473700002201493856011901515       2023                        eng d  a1387-181100aEfficient olefin epoxidation with high turnover rates over ordered mesoporous silica nanoparticles with uniform manganese sites0 aEfficient olefin epoxidation with high turnover rates over order  cDEC0 v3623 a<p>Olefin epoxidation has been studied over a series of mesoporous manganese silicate nanoparticles and tBuOOH. Partial substitution of Si by Mn in silica framework leads to highly dispersed, distorted Mn(III) sites, confirmed by various physicochemical analyses. High conversion and stable styrene oxide, stilbene oxide and epoxy cyclohexane yield have been achieved with MS75 with 1:1.5 ratio of olefin: oxidant. However, at faster reaction rates lower styrene oxide yield is observed at lower Mn-containing catalyst (MS100). High TON, TOF over manganese sites shows accessible monomeric Mn sites. Attributed to high reactant density at redox-active Mn silicate sites due to facile diffusion across shallow pore depth channels of nanoparticulate om-MSx and surface hydrophobic characteristics. The catalysts were found to be stable under recycling and filtration experiments. The excellent stability against leaching of active manganese species indicates stable sites and good textural properties in om-MSx, essential for extended activity.</p>
10aepoxidation10aManganese silicates10aMesoporous silica nanoparticles10aOrdered mesoporous silica10apH adjustment1 aNegi, Sanjay, Singh1 aKhatri, Prateek1 aSingh, Anand, Pal  uhttps://library.ncl.res.in/content/efficient-olefin-epoxidation-high-turnover-rates-over-ordered-mesoporous-silica