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In this study, we assessed the effect of the incorporation of multi-walled carbon nanotubes (MWCNT) on a TiO2 support containing different active metals to obtain Metal/TiO2-MWCNT photocatalytic systems. The materials prepared in this work were characterized by ICP-OES, TEM, EDX, XRD, PL, UV–vis, and nitrogen physisorption techniques. Among those investigated metals, Cu was shown to be the most promising for the present application. The assessment of the photocatalytic performance of Cu/TiO2-MWCNT with various Cu contents revealed that the catalytic activity depends on the Cu loading and the photocatalyst with 1 wt.% of Cu displayed the best performance among investigated. The incorporation of MWCNT in the support enhanced the photocatalytic activity towards the production of H2 under visible and UV–vis light irradiation at room temperature. The authors thank Ministerio de Ciencia Innovación y Universidades and FEDER (Project RTI2018-095291-B-I00) and the Generalitat Valenciana (PROMETEOII/2018/076) for financial support. JFC thanks MINECO for a researcher formation grant (BES-2016-078079). MNG gratefully acknowledges Generalitat Valenciana and Plan GenT (CDEIGENT/2018/027) for the postdoctoral grant. The present work was partially supported by Grants-in-Aid for Scientific Research (Nos. 26220911, 19H00838) from the Japan Society for the Promotion of Science (JSPS) and MEXT. KM, YK, and HY thank MEXT program “Elements Strategy Initiative to Form Core Research Center.

This work constitutes a guide towards the preparation of metal-organic framework materials (MOF) supported and/or confined in activated carbon monoliths (ACM). The resulting hybrid porous materials exhibit improved physico-chemical properties as compared with their parent constituents. The different hybrids were obtained exploring several experimental approaches, which were thoroughly discussed. All hybrids were characterized by N2 adsorption isotherms, SEM, TGA and XRD techniques. The characterization studies pointed out that the preparation conditions are of paramount importance in defining the nucleation and growth of HKUST-1, either outside of the carbon grains (surface coating), and/or in the internal pores (bulk confinement). While the surface coating was achieved by directly synthesizing the MOF in presence of the ACM (i.e. in-situ synthesis), bulk confinement is favored after applying an additional step that involves a pre-nucleation at low temperatures (5 °C). The hybrid material with the best performance, sample A5(1), shows enhanced mechanical properties compared to its parent counterparts, combined with high apparent surface area (up to 1300 m2/g), an improved crushing strength (about 8 times superior to ACM) and a geometrical density of around 0.45 cm3/g, which almost duplicates that of ACM. Last but not least, the adsorption behavior of the hybrid was tested for CO2 and CH4 adsorption. Application of IAST equation to the single component adsorption isotherms at room temperature gives rise to a CO2/CH4 selectivity factor of 5.5 in the hybrid material, larger than that on ACM (S = 3.5). This work was supported by MINECO projects: MAT2013-45008-p. MEC wants to thank the Spanish Government for the fellowship FPU AP2010-4920.

We have performed the synthesis of TiO2-MWCNT composites focusing on the distribution of the photoactive phase on the carbon active sites existing in the MWCNTs, and its effect on the properties of the composites for the abatement of propene. We have used different approaches for the dispersion of MWCNTs during the synthesis; 1) an ultrasound bath for 5 minutes, 2) an ultrasound bath for 60 minutes, and 3) an ultrasound probe for 5 min. We observed that the incorporation of MWCNTs in the TiO2 synthesis improves the catalytic activity in the photooxidation of propene, but the best results are obtained for ultrasound probe treatment. A good dispersion of the MWCNT and an increase in the active surface area or surface oxygen functionalities of the MWCNTs are key factors to achieve improved photocatalytic activity for total propene oxidation, thus benefitting from the synergy between TiO2 and MWCNT. The authors thank Ministerio de Ciencia Innovación y Universidades and FEDER (Project RTI2018-095291-B-I00) and the Generalitat Valenciana (PROMETEOII/2018/076) for financial support. JFC thanks MINECO for a researcher formation grant (BES-2016-078079).