Cobalt chalcogenides

A nonactive electrode may include noble metals such as gold, silver, and platinum, the so-called sp-metals such as In, Ga, Cd, Bi, as well as transition (or d) metals such as nickel or cobalt. Carbon electrodes and semiconductors such as indium tin oxide [1], diamond [2], and conducting polymers may fall into the category of nonactive electrodes in appropriate solutions, as do composite materials that contain metal oxides or chalcogenides. The behavior of active electrodes in nonaqueous solution is discussed separately in the next chapter. 

Other non-precious metal chalcogenides centers containing cobalt have been also synthesized following the template depicted in Fig. 9. In this woik, the in sitn free-surfactant method for carbon supported COxXy (X = S, Se) based on the decomposition of cobalt carbonyls was obtained. To control the growth of the metal nanoparticles and to prevent agglomeration, the use of stabilizers, e.g., donor hgands, polymers and surfactants, i.e., oleic acid (OA), trioctylphosphine oxide (TOPO), trioctyl-phosphine (TOP) and triphenylphosphine (TPP) are necessary. ... 

Chalcogenides are commonly synthesized by this method. The metal sulphide syntheses have been carried out in ethanol, water, " and ethylenediamine, " whereas the sources of metal ions have been acetates or the chlorides. The precursor for sulfur is usually thioacetamide or thiourea. Nanoparticle synthesis of d-block elements have also been carried out, for example, platinum, gold, cobalt, iron, palladium, gold, nickel, and bimetallic alloys such as Co/Cu, 52i Pt/Ru, i Au/Pd, i Fe/Co. ... 

Among the available precursors, NNM macrocycles such as iron(lll) 5,10,15,20-tetrakis(4-methoxyphenyl)-21 H,23H-porphine (C44H36ClFeN404, Fe-TMPP), cobalt(n) 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine (C44H36C0N4O4, Co-TMPP), ironfll) phthalocyanine (C32Hi6FeNg, Fe-PC), cobaltfll) phthalocyanine (C32Hi6CoNg, Co-PC), and chalcogenides have been considered so far to replace PGM-based catalysts for ORR (Fig. 3) [34-39]. 

Electrocatalytic ORR carries out in three pathways the 1-electron transfer pathway, producing superoxide ion the 2-electron transfer pathway, producing hydrogen peroxide and the 4-electron transfer pathway, producing water. In a non-aqueous aprotic solvent system, a room-temperature ionic liquid system, and on specific transition-metal, macrocyclic-compounds-coated graphite electrodes in alkaline solutions, 1-electron reduction can be observed. Carbon materials, quinone and derivatives, mono-nuclear cobalt macrocyclic compounds, and some chalcogenides can only catalyze 2-electron ORR. Noble metal, noble metal alloy materials, iron-macrocyclic complexes, di-nuclear cobalt macrocyclic complexes, some chalcogenides, and transition-metal carbide-promoted Pt catalysts can catalyze 4-electron reduction. 

This section deals with the ternary compounds formed by rare earth elements and chalcogenides with the elements of groups VI through VIII chromium, manganese, iron, cobalt, nickel and molybdenum. 

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