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Anatase TiO 2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO 2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption analysis, UV–vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO 2 NSs possess high surface area up to 378 m 2 g − 1 . The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO 2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO 2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment. [ABSTRACT FROM AUTHOR]

A brand-new Co catalyst with precisely tailored Co nanoparticle/single atom (NP/SA) ratio was encapsulated into a hollow carbon sphere for aqueous levulinic acid hydrogenation to γ-valerolactone. Synergism between carbonyl activation and hydrogen dissociation was realized over the Co catalyst with an isoatomic ratio of NPs and SAs, and superior stability was achieved due to the unique yolk-structure. [Display omitted] • Yolk-shell Co catalysts with a raspberry core and a hollow N -doped carbon shell. • Co nanoparticle/single atom ratio was controlled precisely. • Superior activity and stability of the Co catalyst for LA hydrogenation. • The synergism between Co nanoparticles and single atoms. • Co single atoms and nanoparticles facilitate C O and H 2 activation, respectively. Precise and facile tailoring of metal nanoparticle/single-atom ratio to optimize the catalytic hydrogenation activity and durability is important yet challenging, owing to the lack of efficient synthetic methodology. Herein, we report a brand-new Co catalyst with precisely tailored Co NP/Co SA ratio encapsulated into a hollow carbon sphere, skillfully fabricated by stepwise coating of bimetallic Zn/Co zeolitic imidazole frameworks with silica and 8-quinolinol modified chitosan before pyrolysis and acid washing. The transformation of the target catalyst and the tailoring of Co NP/Co SA ratio are well investigated by various characterization techniques including TEM, aberration-corrected scanning TEM (AC-STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), etc. It is found that the yolk-shell structured Co catalyst integrated with nearly equivalent nanoparticles and sing-atoms are highly active and stable towards aqueous levulinic acid (LA) hydrogenation to γ-valerolactone (GVL). Combined with H 2 -TPD and LA adsorbed FT-IR investigations, it is revealed that the superior activity originates from the synergism of Co nanoparticles and single-atoms, since H 2 dissociation and C O adsorption are facilitated by Co nanoparticles and single-atoms, respectively, leading to a lowered energy barrier during the hydrogenation reaction. This study will shed light on the precise tailoring of metal nanoparticle/single-atom ratio and also provides a new insight into the development of highly efficient non-noble metal catalysts for sustainable biomass conversion. [ABSTRACT FROM AUTHOR]