No abstract

In this work, MoS 2 /TiO 2 nanoparticles were investigated as a bifunctional catalyst for the conversion of oleic acid to diesel-range hydrocarbons and the removal of carbonaceous deposits on the catalyst surface. The entire series of catalysts with different mass loadings of MoS 2 (5−20 wt %) was synthesized via a solvothermal method. MoS 2 /TiO 2 nanoparticles had a high degree of MoS 2 dispersion on anatase TiO 2 support. The Brunauer− Emmett−Teller analysis reveals a marked increase in the specific surface area of 20 wt % MoS 2 /TiO 2 (171 m 2 g −1 ) compared to bare TiO 2 (121 m 2 g −1 ). For the catalytic conversion of oleic acid, it was found that the fraction of diesel-range hydrocarbons (C17−C18) in liquid products enhanced with increasing MoS 2 mass loading. Moreover, the MoS 2 /TiO 2 catalyst also presented high selectivity toward C18 hydrocarbons. This suggests that hydrodeoxygenation (HDO) was a dominant pathway for the catalytic conversion of oleic acid over MoS 2 /TiO 2 nanoparticles. For the photocatalytic degradation, to clean up the MoS 2 /TiO 2 catalyst after being used for the oleic acid conversion, hence, the photocatalytic removal of carbonaceous deposits on the surface was studied. The results demonstrate that carbonaceous deposits on spent MoS 2 /TiO 2 were removed under UV-light irradiation due to the photodegradation property of the TiO 2 support. Therefore, the active surface of the MoS 2 /TiO 2 catalyst was simply recovered by a facile approach at room temperature.

Here, silver indium sulfide (AgInS2/gallium selenide core/shell quantum dots (QDs) were developed to exhibit red band-edge emission. Previously, we developed AgInS2/gallium sulfide core/shell QDs, which exhibited yellow band-edge photoluminescence (PL). Upon the gallium selenide shell growth, the PL spectra redshifted by more than 100 nm owing to an indirect transition between the core and shell (called the type-II characteristic). After the posttreatment with HCl, the PL wavelength was further redshifted by the formation of Ag–In–S–Se alloyed cores with a narrow bandgap, and the PL intensity increased because of the formation of a quasi-type-II band alignment. In addition, the PL wavelength could be tuned between deep-red and yellow by varying the S/(S+Se) ratio in the Ga–S–Se ternary shells. Based on the long lifetime of the QDs with the alloyed shells, it was suggested that the electronic structure of these alloyed shell QDs is the full type II.