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This study is the first report on the preparation of mesoporous carbon/silica (MCS) nanocomposites with tunable mesoporosity and hydrophobicity using natural rubber (NR) as a renewable and cheap carbon source. A series of mesoporous nanocomposites based on NR and hexagonal mesoporous silica (HMS) were prepared via an in situ sol-gel process and used as precursors; then, they were converted into MCS materials by controlled carbonization. The NR/HMS precursors exhibited a high dispersion of rubber phase incorporated into the mesostructured silica framework as confirmed by small-angle X-ray scattering and high-resolution transmission electron microscopy. An increase in the carbonization temperature up to 700 °C resulted in MCS nanocomposites with a well-ordered mesostructure and uniform framework-confined wormhole-like channels. The NR/HMS nanocomposites possessed high specific surface area (500-675 m 2 g −1) and large pore volume (1.14-1.44 cm 3 g −1). The carbon content of MCS (3.0-16.1 wt%) was increased with an increase in the H 2 So 4 concentration. Raman spectroscopy and X-ray photoelectron spectroscopy revealed the high dispersion of graphene oxidelike carbonaceous moieties in MCS materials; the type and amount of oxygen-containing groups in obtained MCS materials were determined by H 2 So 4 concentration. The enhanced hydrophobicity of MCS nanocomposites was related to the carbon content and the depletion of surface silanol groups, as confirmed by the water sorption measurement. The study on the controlled release of diclofenac in simulated gastrointestinal environment suggests a potential application of MCS materials as drug carriers. Mesoporous carbon/silica nanocomposites (MCS) have received considerable attention in catalysis 1 , adsorption 2 , energy storage 3,4 , and drug delivery 5 owing to the combined advantages of inorganic silica and organic carbon in their mesostructure. Silica framework provides high mesoporosity, specific surface area, and thermal/mechanical stability. Due to the high density of silanol groups, the silica surface can be simply modified by either direct co-condensation or postsynthesis grafting to acquire various chemically active functionalities to serve a wide range of applications 6,7. However, amorphous carbon is characterized by its tunable physicochemical properties by controlling the ratio of sp 2 /sp 3 bonds and quantity of heteroatoms (i.e., oxygen) 8,9. The oxygen-containing functional groups on the carbon surface provide acidic (i.e., carboxyl, lactone, and phenol) and basic (i.e., pyrone, chromene, ether, and carbonyl) properties 10. An increase in the amount of sp 2-hybridized carbon transforms amorphous carbon into graphite-like carbon with enhanced textural properties and chemical reactivity 11,12. Typically, the preparation of MCS materials consists of two steps. The first step is to introduce an organic substance (e.g., glucose, furfuryl alcohol, phenol, and formaldehyde) as a carbon source into mesostructured silica. Then, the organic substance is converted to ...

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5-Hydroxymethylfurfural (HMF) is one of the most important lignocellulosic biomass-derived platform molecules for production of renewable fuel additives, liquid hydrocarbon fuels, and value-added chemicals. The present work developed niobium oxides (Nb2O5) supported on mesoporous carbon/silica nanocomposite (MCS), as novel solid base catalyst for synthesis of HMF via one-pot glucose conversion in a biphasic solvent. The MCS material was prepared via carbonization using natural rubber dispersed in hexagonal mesoporous silica (HMS) as a precursor. The Nb2O5 supported on MCS (Nb/MCS) catalyst with an niobium (Nb) loading amount of 10 wt.% (10-Nb/MCS) was characterized by high dispersion, and so tiny crystallites of Nb2O5, on the MCS surface, good textural properties, and the presence of Bronsted and Lewis acid sites with weak-to-medium strength. By varying the Nb loading amount, the crystallite size of Nb2O5 and molar ratio of Bronsted/Lewis acidity could be tuned. When compared to the pure silica HMS-supported Nb catalyst, the Nb/MCS material showed a superior glucose conversion and HMF yield. The highest HMF yield of 57.5% was achieved at 93.2% glucose conversion when using 10-Nb/MCS as catalyst (5 wt.% loading with respect to the mass of glucose) at 190 °C for 1 h. Furthermore, 10-Nb/MCS had excellent catalytic stability, being reused in the reaction for five consecutive cycles during which both the glucose conversion and HMF yield were insignificantly changed. Its superior performance was ascribed to the suitable ratio of Brønsted/Lewis acid sites, and the hydrophobic properties generated from the carbon moieties dispersed in the MCS nanocomposite.