Synthesis and Properties of Cobalt Sulfide Phases: CoS₂ and Co₉S₈

Abstract

Single phase cobalt disulfide (CoS2) nanoparticles were prepared by thermal decomposition of cobalt‐thiourea complex at a low temperature (400 °C). CoS2 nanoparticles exhibit ferromagnetic ordering at 122 K below which the temperature dependent resistivity of cold pressed nanoparticles deviates from metallic behavior and shows a broad maximum. Just below TC, it also exhibits a large magnetoresistance effect (6.5 %). A mixture of CoS and Co9S8 phases were obtained between the temperature interval 400 °C < T < 1000 °C. At 1000 °C, a pure bulk Co9S8 phase was obtained. It exhibits magnetic hysteresis typical of a ferromagnet at room temperature and a peak in magnetization at low temperature with a strong relaxation indicating possible spin glass state.

Synthesis of nickel and cobalt sulfide nanoparticles using a low cost sonochemical method

“…More recently, Hoodles et al [35] prepared Co 9 S 8 by heating Co 3 O 4 in a stream of 9.8% H 2 S in H 2 . Milder routes for the synthesis of nanosized cobalt sulfides have been developed during the last decade, like decomposition of cobalt−thiourea complexes [33, 50], wet chemical methods [36, 41, 42], microwave assisted methods [32, 48], and in the first place the hydrothermal/solvothermal method [34, 39, 43, 46, 47, 49, 50, 51, 52]. It should be mentioned that You et al report significant advantages of CoS prepared by a microwave synthesis when compared to counterparts prepared by the solvothermal method [48].…”

A highly active hydrogen evolution electrocatalyst based on a cobalt–nickel sulfide composite electrode

“…Our synthetic strategy was inspired by earlier works reporting the formation of pure cobalt sulfide nanoparticles through the thermal annealing under inert atmosphere of a preformed Cothiourea molecular complex in methanol. 37,38 In our method the Cothiourea complex was first adsorbed onto a pre-cleaned Ni foam (Nif) through dip coating, and subsequently annealed under N 2 . The metal loading in the electrode can be controlled simply by repeating the two steps of dip coating-annealing (see Experimental details †).…”

Novel Non‐Carbon Sulfur Hosts Based on Strong Chemisorption for Lithium–Sulfur Batteries

“…Co 9 S 8 , which is a member of the pentlandite family, with good thermal stability and relatively high room‐temperature conductivity of 290 S cm −1 , has great potential to serve as a sulfur host for Li–S batteries . Nazar and co‐workers prepared graphene‐like Co 9 S 8 with high surface area and hierarchical porosity .…”