Herein we report the synthesis of gold nanoclusters upon the surface of Indonesia natural zeolite, denoted as Au/INZ. The as-prepared material has been characterized using X-ray diffraction, atomic absorption spectroscopy, UV-Vis diffuse reflectance spectroscopy, transmission electron microscopy, selected area electron diffraction and N 2 physisorption. These characterizations confirm the welldefined gold nanoclusters formed on the surface of Au/INZ. Our catalyst has been applied for the reduction of p-nitrophenol to p-aminophenol. The reduction conversion of ca. 95 % was achieved by the use of 50 mg Au/INZ for 10 min with the observed rate constant (k obs ) was of 0.818 min -1 . The E a of the reaction was 16.9 kJ/mol, indicating the diffusion-controlled mechanism. In addition, the reusability test confirmed that our catalyst can be exploited for several times without the significant loss of its high activity.Electronic supplementary material The online version of this article (
Biochar (BCR) was obtained from the pyrolysis of a palm-oil-empty fruit bunch at 773 K for 2 h and used as a catalyst for the hydrodeoxygenation (HDO) of guaiacol (GUA) as a bio-oil model compound. Brunauer–Emmet–Teller surface area analysis, NH3 and CO2-temperature-programmed desorption, scanning electron microscope–dispersive X-ray spectroscopy, CHN analysis and X-ray fluorescence spectroscopy suggested that macroporous and mesoporous structures were formed in BCR with a co-presence of hydrophilic and hydrophobic sites and acid–base behavior. A combination of infrared, Raman and inelastic neutron scattering (INS) was carried out to achieve a complete vibrational assignment of BCR. The CH–OH ratio in BCR is ~5, showing that the hydroxyl functional groups are a minority species. There was no evidence for any aromatic C–H stretch modes in the infrared, but they are clearly seen in the INS and are the majority species, with a ratio of sp3–CH:sp2–CH of 1:1.3. The hydrogen bound to sp2–C is largely present as isolated C–H bonds, rather than adjacent C–H bonds. The Raman spectrum shows the characteristic G band (ideal graphitic lattice) and three D bands (disordered graphitic lattice, amorphous carbon, and defective graphitic lattice) of sp2 carbons. Adsorbed water in BCR is present as disordered layers on the surface rather than trapped in voids in the material and could be removed easily by drying prior to catalysis. Catalytic testing demonstrated that BCR was able to catalyze the HDO of GUA, yielding phenol and cresols as the major products. Phenol was produced both from the direct demethoxylation of GUA, as well as through the demethylation pathway via the formation of catechol as the intermediate followed by deoxygenation.
Nanoparticles have received much recent attention in areas such as chemistry, physics, materials science, life sciences and engineering. Many physical and chemical methods have disadvantages such as high costs, the use of chemicals that are harmful to the environment and health. The green nanoparticle synthesis approach, using plant extracts as a capping agent of nanoparticles, is the right solution to produce nanoparticles that are effective and environmentally friendly. Micro and macroalgae in the use of nanoparticle synthesis are increasingly being developed. However, the use of Sargassum in chemical applications has not been fully explained, and there are still some drawbacks that must be overcome. Sargassum spp. biomass has been recognized as a natural, renewable, and cost-effective material to become a capping agent for nanoparticles. This review is a summary highlighting the potential of metal-Sargassum composite based materials as an alternative to biological protective activities, such as antibacterials. Synthesis and characterization of materials, key factors influencing material performance, and distribution of Sargassum in Indonesia are considered by the Government of Indonesia and investors in seeing opportunities to use Sargassum as an advanced material.
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