Nanocrystalline CoSn2-carbon composite electrode prepared by using sonochemistry

Influence of M/A substitution on material properties of intermetallic compounds MSn2 (M = Fe, and Co; A = Li, and Na): a first-principles study

Structural, elastic, and electronic properties, phonons, and defects of MASn₂ (M = Fe, and Co; A = Li, and Na) were studied with DFT calculations.

Structurally Ordered Intermetallic Cobalt Stannide Nanocrystals for High-Performance Electrocatalytic Overall Water-Splitting

The synthesis of structurally ordered non-noble intermetallic cobalt stannide (CoSn₂ ) nanocrystals and their utilization for high-performance electrocatalytic overall water-splitting is presented. The structurally and electronically beneficial properties of the tetragonal CoSn₂ exhibit a considerably low overpotential for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) on fluorine-doped tin oxide (FTO) and Ni foam (NF). Loss of Sn from the crystal lattices and oxidation of Co under strongly alkaline conditions furnishes highly disordered amorphous active CoO_x (H), the catalytically active structure for OER. The Co⁰ atoms in the CoSn₂ act as active sites for HER and the presence of Sn provides efficient electrical conductivity. This intermetallic phase is a novel type of cost-effective and competitive bifunctional electrocatalysts and predestinated for overall water-splitting devices: A two-electrode electrolyzer with CoSn₂ on NF delivers a cell voltage of merely 1.55 V at 10 mA cm^-2 maintaining long-term stability.

High-intensity ultrasonication as a way to prepare graphene/amorphous iron oxyhydroxide hybrid electrode with high capacity in lithium battery

The preparation of graphene/iron oxyhydroxide hybrid electrode material with very homogeneous distribution and close contact of graphene and amorphous iron oxyhydroxide nanoparticles has been achieved by using high-intensity ultrasonication. Due to the negative charge of the graphene surface, iron ions are attracted toward the surface of dispersed graphene, according to the zeta potential measurements. The anchoring of the FeO(OH) particles to the graphene layers has been revealed by using mainly TEM, XPS and EPR. TEM observations show that the size of the iron oxide particles is about 4 nm. The ultrasonication treatment is the key parameter to achieve small particle size in these graphene/iron oxyhydroxide hybrid materials. The electrochemical behavior of composite graphene/amorphous iron oxyhydroxide prepared by using high-intensity ultrasonication is outstanding in terms of gravimetric capacity and cycling stability, particularly when metallic foam is used as both the substrate and current collector. The XRD-amorphous character of iron oxyhydroxide in the hybrid electrode material and the small particle size contribute to achieve the improved electrochemical performance.