The Effect of KOH Treatment on the Chemical Structure and Electrocatalytic Activity of Reduced Graphene Oxide Materials.

Reduced graphene oxide (rG-O)-based materials have great potential as metal-free electrocatalysts for the oxygen reduction reaction (ORR) owing to their electrical and electrochemical properties and large surface area. Long-term durability and chemical stability of the catalysts in the presence of electrolytes such as aqueous KOH solution are important for their use in practical applications. In this study, three types of rG-O and rG-O-K (rG-O after reaction with KOH) materials were synthesized. The chemical structures, surface areas, and catalytic ORR performances of the rG-O materials were compared with those of the corresponding rG-O-K materials. The onset potentials of the rG-O materials for electrocatalytic reduction of oxygen are almost the same as those of the corresponding rG-O-K materials; however, the current density and the number of transferred electrons are significantly reduced. These data show that the catalytic ORR performance of rG-O-based materials can be altered by KOH.

Production of Metal-Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances.

A novel metal-free composite (GN) composed of two types of carbon-based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well-dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light.

Coordination Chemistry of [Co(acac)2 ] with N-Doped Graphene: Implications for Oxygen Reduction Reaction Reactivity of Organometallic Co-O4 -N Species.

Hybridization of organometallic complexes with graphene-based materials can give rise to enhanced catalytic performance. Understanding the chemical structures within hybrid materials is of primary importance. In this work, archetypical hybrid materials are synthesized by the reaction of an organometallic complex, [Co(II) (acac)2 ] (acac=acetylacetonate), with N-doped graphene-based materials at room temperature. Experimental characterization of the hybrid materials and theoretical calculations reveal that the organometallic cobalt-containing species is coordinated to heterocyclic groups in N-doped graphene as well as to its parental acac ligands. The hybrid material shows high electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media, and superior durability and methanol tolerance to a Pt/C catalyst. Based on the chemical structures and ORR experiments, the catalytically active species is identified as a Co-O4 -N structure.