Proactive Effect of Algae-Based Graphene Support on the Oxygen Evolution Reaction Electrocatalytic Activity of NiFe.

The preparation of graphene materials from biomass resources is still a challenge, even more so if they are going to be employed as supports for electrocatalysts for water splitting. Herein, we describe the preparation and characterization of graphene oxides (GOs) from solid macroalgae waste obtained after processing an agar-agar residue. The structural and morphological characterization of the obtained GO confirm the presence of a lamellar material that is composed of few layers with an increased number of heteroatoms (including nitrogen) if compared with those observed in a GO obtained from graphite (reference).

An approach to classification and capacitance expressions in electrochemical capacitors technology.

The proliferation of novel types and designs of electrochemical capacitors makes it necessary to obtain a better understanding of the behavior of these systems together with a more systematic classification of them. In this study a rational classification of supercapacitors based on the charge storage mechanism and the active material of each electrode is proposed. The internationally accepted terminology - the terms symmetric, asymmetric and hybrid - is also clarified in an attempt to standardize the current definitions and facilitate the systematic classification of each device.

Tailoring micro-mesoporosity in activated carbon fibers to enhance SO₂ catalytic oxidation.

Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers.

Graphite felt modified with bismuth nanoparticles as negative electrode in a vanadium redox flow battery.

A graphite felt decorated with bismuth nanoparticles was studied as negative electrode in a vanadium redox flow battery (VRFB). The results confirm the excellent electrochemical performance of the bismuth modified electrode in terms of the reversibility of the V(3+) /V(2+) redox reactions and its long-term cycling performance. Moreover a mechanism that explains the role that Bi nanoparticles play in the redox reactions in this negative half-cell is proposed.

High performance activated carbon for benzene/toluene adsorption from industrial wastewater.

A coal-tar-derived mesophase was chemically activated to produce a high surface area (~3200 m(2)/g) carbon with a porosity made up of both micropores and mesopores. Its adsorption capacities were found to be among the highest ever reported in literature, reaching values of 860 mg/g and 1200 mg/g for the adsorption of benzene and toluene, respectively, and 1200 mg/g for the combined adsorption of benzene and toluene from an industrial wastewater. Such high values imply that the entire pore system, including the mesopore fraction, is involved in the adsorption process.

Preparation of low toxicity pitches by thermal oxidative condensation of anthracene oil.

This article describes a novel industrial procedure for producing new pitches of low toxicity from anthracene oil, a byproduct of coal tar distillation. The procedure involves oxidative treatment in order to polymerize and condense the anthracene oil components followed by thermal treatment and distillation in order to obtain a pitch with the desired parameters. This sequence (oxidative treatment/thermal treatment/distillation) was repeated four times under reaction conditions of increasing severity in four cycles of anthracene oil processing to obtain the four pitches.

Matrix-iron interactions in carbon-embedded iron oxide nanoparticles.

This study deals with the interaction between iron oxide nanoparticles and a carbon-rich source (pitch) during the carbonization process, resulting in a carbon material of high added value. The iron oxide nanoparticles were prepared by different procedures in order to obtain Fe2O3 and Fe3O4 with different particle sizes. The results show that the presence of iron oxide modifies the thermal behaviour of the pitch, especially in the temperature range of 400-500 degrees C when the pre-graphitic order in the carbon matrix is formed.

The adsorption of chromium (VI) from industrial wastewater by acid and base-activated lignocellulosic residues.

This study deals with the adsorption of Cr(VI) from synthetic and industrial wastewater, produced by a sewage plant. The activated carbons were prepared from a lignocellulosic raw material by thermal treatment at 450 and 650 degrees C in the presence of acid (AlCl(3), HCl, H(3)PO(4) and H(2)SO(4)) and base (NaOH) agents. To optimize the adsorption of Cr(VI), the chemical modifications caused by each activating agent (related to the capability of Cr(VI) removal), and the optimal experimental conditions of the pH, Cr(VI) concentration, adsorbent dose and residence time, were studied.