Single-atom functionalization of transition-metal dichalcogenide (TMD) nanosheets is a powerful strategy to tune the optical, magnetic, and catalytic properties of twodimensional materials. In this work, we demonstrate a simple solution-phase method to generate nucleophilic sulfide sites on colloidal WS 2 nanosheets that subsequently serve as ligands for Ni single atoms. These materials can be controllably functionalized with varying amounts of Ni on the surface ranging from 9% to 47% coverage with respect to W. High-resolution scanning transmission electron microscopy coupled to electron energy loss spectroscopy and X-ray absorption spectroscopy indicate that adsorbed Ni species bind as single atoms at low coverage and a mixture of single atoms and multimetallic clusters at high coverage. The Ni single atoms adsorbed on WS 2 show altered electronic properties, and both the electronic perturbation and isolated atom geometry play a role in enhancing the intrinsic catalytic activity of Ni-WS 2 samples for the electrochemical oxygen evolution reaction.

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Lithium cobaltite, LiCo 2 O 4 , prepared by thermal decomposition of nitrates salts was synthesized at 400 ºC. X-ray Rietveld refinement showed the presence of two phases: a cubic spinel (Co 3 O 4) and other corresponding to spinel-like, which could not be classified as LiCo 2 O 4 or LiCoO 2 since both crystallized in Fd3m S.G. Electrochemical determinations (charge-discharge curves and impedance spectroscopy measurements) showed that Li + ion is inserted into the spinel lattice, with D = 8 10-16 cm s-1 at 2.00-2.25 V potential range whereas lithium extraction occurred at 3.2-3.8 V potential range.

Cobalt sulfide nanomaterials are among the most active and stable catalysts for the electrocatalytic oxygen reduction reaction in pH 7 electrolyte. However, due to the complexity and dynamism of the...

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