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Highlights• TiO2-RGO nanocomposites presented, in all the cases studied, improved photocatalytic properties compared to bare TiO2.• An optimal composition, in terms of TiO2/RGO ratio was found in both series of nanocomposites; however, superior activity was found for those prepared by direct sol-gel route.• Nanocomposites prepared by sol-gel method presented improved textural properties than those prepared following a hydrothermal route.• Optimization in the preparation of hybrid photocatalystsis needed to obtain materials with finer properties for effective application in environmental AbstractIn this study, two different preparation methods of titanium dioxide nanoparticles/reduced graphene oxide nanocomposites were investigated using direct sol-gel method followed by 3 hydrothermal treatment or simple hydrothermal route. A different amount of graphene (1-20%) was mixed with TiO2 for both series of samples in order to improve the photocatalytic activity. The influence of the preparation method on the physico-chemical properties was established by different characterization methods and the photocatalytic degradation of methylene blue (MB) under UV light irradiation was used as test reaction. The highest photocatalytic activity was observed for the nanocomposites containing 10 wt% of graphene.The elimination of MB can reach 93% and 82% for the nanocomposites with 10 wt% graphene prepared by the sol-gel and hydrothermal methods, respectively. These photocatalysts are promising for practical application in nanotechnology.

CoAl-spinel nanoparticles prepared by liquid-feed flame spray pyrolysis (LÀ F FSP) and activated by reduction at different temperatures were used to investigate the hydrogenation process of furfural (FA) under mild conditions. Reduction of the spinel at 500°C resulted in high FA conversion and selectivity to furfuryl alcohol (FFA, 81 % yield, in 1 hour). Reduction at higher temperatures (i. e., 700 and 850°C) led to the direct formation of diols (i. e., 1,5-PeD and 1,2-PeD) from FA. The differences in activity are attributed to the formation of surface metallic cobalt nanoparticles upon reduction at high temperature. A maximum of 30 % 1,5-PeD was yielded after 8 hours of reaction under the optimized conditions of150°C, 30 bar of H 2 and with 40 mg of catalyst reduced at 700°C. This is the first report on the direct catalytic conversion of furfural to1,5-pentanediol with a nonnoble metal solid catalyst. either form 1,2-PeD or 1,5-PeD or both. The second one combines hydrogenation of FFA to tetrahydrofurfuryl alcohol (THFA) followed by hydrogenolysis of THFA (Scheme 1, route II). Independently of which one is employed, FFA or THFA are usually chosen as starting reactant to obtain the diols.Due to the high amount of competitive reactions that FA can undergo (Scheme 1), the direct use of FA as starting material remains a challenge. Xu et al. reported 1,5-PeD production from FA over platinum supported inverse Co-spinel,

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