Miguel Angelo Schettino

• Federal University of Espírito Santo

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production of supercapacitor electrodes. In the present...

Biochar and ashes derived from coffee husk were used as heterogeneous catalysts in the synthesis of biodiesel through a transesterification reaction. The catalysts were obtained from the carbonization, activation, and combustion of raw coffee husks. Their properties were characterized by solid-state 13C and 31P nuclear magnetic resonance (NMR) spec...

Graphene quantum dots (GQDs) are nanosized systems that combine beneficial properties typical of graphenic materials (such as chemical stability, biocompatibility and ease of preparation from low-cost precursors) with remarkable photoluminescent features. GQDs are well-known for their low cytotoxicity and for being promising candidates in applicati...

Using a coprecipitation route in aqueous medium with different precipitating agents (NH4OH and NaOH), iron-oxide nanostructures were prepared with distinct structural and magnetic properties. X-ray diffraction (XRD), ⁵⁷Fe Mossbauer spectroscopy and N2 sorption experiments indicated that the sample synthesized with NaOH had nanocrystalline goethite...

Several groups have announced planning programs for the development of the hydrogen economy. The forecast projections are not yet favorable and seem to run into many limitations related to the real possibility of the distribution of compressed hydrogen (H2) gas in pipelines from centralized H2 production, in addition to other difficulties. One chal...

This work discusses the transition from the use of fossil fuel to the use of a renewable source, supports the production of H2 in a decentralized way from the natural gas of the gas pipeline and biogas, generated locally. The core of the local hydrogen production is the plasma dry reformer developed by PETROBRAS and UFES that allows using both natu...

Ni metal particles, with sizes ranging from 70 to 110 nm, dispersed in activated carbon produced from the babassu coconut endocarp (BAC) were successfully synthesized and evaluated by scanning electron microscopy, dispersive energy X-ray spectroscopy, flame atomic absorption spectroscopy and powder X-ray diffraction. These hybrid BACNi-X materials...

Catalysts containing Na and Ca compounds dispersed in a porous carbon support were prepared by a wet chemical route followed by heat treatments and their catalytic performance in the transesterification reaction of soybean oil with methanol was investigated. The chemical composition and the structural properties of the Na,Ca-based catalysts were mo...

Different catalysts containing CaO particles dispersed in commercial activated carbon were prepared by wet impregnation followed by heat treatments. The catalytic efficiency of the prepared materials was investigated by evaluating their performance in biodiesel production by the transesterification reaction of soybean oil with methanol. The catalys...

Pseudocapacitive materials can enhance the energy storage performance of supercapacitors by making use of surface redox reactions. In recent years, different iron compounds have been investigated as pseudocapacitive materials, showing promising features for supercapacitor electrode applications. Carbon nanocomposites containing iron/phosphorus comp...

Correlations between the photocatalytic activity and the chemical composition of carbon-supported P-Fe-based nanocomposites were found. Nanoporous carbon was prepared by chemical activation with H3PO4 of the endocarp of babassu coconut. The synthesis of the nanocomposites was conducted by aqueous impregnation of the support with Fe(NO3)39H2O and N...

Lignocellulosic biomass has been widely studied as a source of cellulose- and related products, attracting the great interest of researchers dealing with renewable energy sources, vegetable waste recycling and biomaterials. In this work, the babassu coconut shells (epicarp and endocarp) were used for the achievement of products such as cellulose, c...

Tungsten nanowires were deposited by DC magnetron sputtering onto vicinal sapphire substrates with a specific geometry in which the entrance angle (solid angle) of the vapor beam relative to the substrate was modified. Through 2D auto-correlation function analysis, suitable conditions to obtain a nanoscale corrugated surface with a high-order corre...

Activated carbons with well-developed microporosity and containing dispersed nanostructured phosphorus compounds were produced by the chemical activation with H3PO4 of an abundant Brazilian lignocellulosic residue (endocarp of babassu coconut). The chemical nature of the phosphorus-containing species in the produced materials was studied by ¹H, ¹³C...

This work describes the production and characterization of carbon-iron nanocomposites obtained from the decomposition of iron pentacarbonyl (Fe(CO)5) mixed with different carbon materials: a high surface area activated carbon (AC), powdered graphite (G), milled graphite (MG), and carbon black (CB). The nanocomposites were prepared either under argo...

The structural and chemical transformations occurring in alumina-carbon composites upon heat treatment were investigated by using a combination of X-ray diffraction (XRD) and solid-state 27Al nuclear magnetic resonance (NMR) spectroscopy. Two different carbon precursors were employed: a commercial activated carbon and a char obtained by carbonizati...

The pyrolysis of compressed natural gas (CNG) was made by thermal plasma using carbon dioxide(CO2) as working gas. The purpose of this work is the production of H2 from CNG, aiming to use it for the CNGenrichment in order to increase the yield in CNG combustion engines. This technique can also be used to enrichlandfill gas (which contains mainly CH...

The kinetics of formation of NiFe2O4 nanoparticles were investigated where the nanoparticles were produced by the proteic-sol-gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe2O4 nanoparticles i...

Iron-based nanoparticles were prepared by the decomposition of iron pentacarbonyl (Fe(CO)5) inside a porous carbon material. Mössbauer spectroscopy (MS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) revealed that the as-prepared materials were composed of nanometer-sized iron oxide clusters...

Magnetic carbon-based nanomaterials have promising applications in many fields owing to their biocompatibility and thermal/mechanical stability. This study describes a high-temperature X-ray diffraction (XRD) study of the chemical and structural transformations suffered by superparamagnetic iron oxide nanoparticles embedded in porous carbons. The n...

The sodium environments in porous carbon materials prepared from NaOH activation of a char were investigated by means of multiple-field solid-state (23)Na NMR measurements, carried out at magnetic fields of 4.7, 8.45 and 14.1T, with single-pulse excitation and magic angle spinning (MAS). The recorded spectra showed a relatively featureless resonanc...

A detailed investigation was conducted about the process of alkali activation of charred rice hulls using NaOH. A carbon-rich precursor was initially prepared from the pyrolysis of rice hulls under N2 atmosphere, part of it being leached with HF to remove silica. The precursor was then mixed with NaOH, heat-treated at activation temperatures from 6...