Deposition and characterization of IrOx nanofoils on carbon nanotube templates by reactive magnetron sputtering

Highly Efficient Electrocatalysis and Mechanistic Investigation of Intermediate IrOx(OH)y Nanoparticle Films for Water Oxidation

“…The Raman signals for the as-prepared film are observed at 168, 290, 315, and 335 cm –1 (assigned to Ir–OH moieties of the [Ir­(OH) x (OH 2 ) y Cl z ] n − complex species in its compact layer), which is identical with the Raman spectra of a control sample of monomeric hydroxyiridate complex produced by complete alkaline hydrolysis of K 2 IrCl 6 at pH 13. , The peak at 315 cm –1 shifted to 320 cm –1 at 200 °C of the annealing temperature, corresponding to condensation of the complexes in the compact layer during heat treatments at 200 °C. As the annealing temperature increased to 300 and 350 °C, the peaks further shifted to 325 cm –1 with a broad intense band appearing in the vicinity of 516 cm –1 , which agrees with the bridging oxo binding modes of amorphous IrO x . , These two different oxygen binding motifs (hydroxo and bridging oxo) in the films annealed at 300 and 350 °C were also supported by XPS measurements (Figure S4 in the Supporting Information). Raman spectra of the films annealed at 300 and 350 °C did not change when they were immersed in water over 1 day due to insolubility of the deposited film in water, in contrast with the high water solubility of either the as-made film or the film annealed at 200 °C.…”

“…As the annealing temperature increased to 300 and 350 °C, the peaks further shifted to 325 cm −1 with a broad intense band appearing in the vicinity of 516 cm −1 , which agrees with the bridging oxo binding modes of amorphous IrO x . 55,56 These two different oxygen binding motifs (hydroxo and bridging oxo) in the films annealed at 300 and 350 °C were also supported by XPS measurements (Figure S4 in the Supporting Information). Raman spectra of the films annealed at 300 and 350 °C did not change when they were immersed in water over 1 day due to insolubility of the deposited film in water, in contrast with the high water solubility of either the as-made film or the film annealed at 200 °C.…”

“…The ratio of the peak area for Ir–OH signals (300 and 325 cm –1 ) versus bridging oxo (∼516 cm –1 ) for amorphous IrO x decreased from 0.53 to 0.22 with an annealing temperature increase from 300 to 350 °C, showing that the content fraction of the Ir–OH signals decreases at 350 °C. The Ir–OH signals completely disappeared at 400 °C, and the broad intense band at 516 cm –1 and weak bands at 302 and 713 cm –1 appeared, which are a sign of formation of amorphous IrO x on the basis of the literature. , The characteristic bands of crystalline IrO 2 at 559, 729, and 746 cm –1 which are assigned as E g , B 2g ,and A 1g phonon bands, respectively, started to appear at 450 °C, being prominent at 500 °C. − The sequential formation mechanism of the IrO x film is illustrated in Scheme b. The precursor complex undergoes gradual condensation during annealing and nanoparticle formation is initiated through shrinkage of the compact complex layer.…”

“…55,56 The characteristic bands of crystalline IrO 2 at 559, 729, and 746 cm −1 which are assigned as E g , B 2g ,and A 1g phonon bands, respectively, started to appear at 450 °C, being prominent at 500 °C.57−59 The sequential formation mechanism of the IrO x film is illustrated in Scheme 1b.…”

Conformal Fe3O4 Sheath on Aligned Carbon Nanotube Scaffolds as High-Performance Anodes for Lithium Ion Batteries

“…With this method, uniform deposition of nanosized carbides, nitrides, and oxides with low dimensionality on a variety of substrates was reported. , However, attempts of conformal coating on CNTs were always prohibited by the small pore sizes of the CNT matrix. Instead, nanoflakes were formed on the top of the CNT array substrate . To tackle this issue, Au nanoparticles could be initially sputtered into a room temperature ionic liquid and then self-assembled onto already dispersed CNTs .…”