Electrodeposition of Cobalt from LiCl-Based Highly Concentrated Aqueous Solution: Crystal Phase and Hydrogen Content

The relationship between the crystal phase and absorbed hydrogen in cobalt electrodeposited from a LiCl-based highly concentrated (HC) aqueous solution was investigated using X-ray diffraction and thermal desorption spectroscopy. We expected that the use of an HC solution would enable the electrodeposition of cobalt without hydrogen evolution and the concomitant hydrogen absorption. The current efficiency of cobalt deposition was more than 99% at potentials above −0.8 V vs. Ag/AgCl, indicating that hydrogen evolution is really suppressed, but the electrodeposited cobalt accompanied the fcc phase irrespective of the deposition temperature. Moreover, electrodeposited cobalt contained a large amount of hydrogen despite the high current efficiency. The hydrogen content of cobalt obtained at 100°C was approximately 10% of that obtained at room temperature; however, the fcc phase was still co-deposited, suggesting that factors other than hydrogen could be responsible for fcc-Co formation. The reason for hydrogen inclusion from the HC solution is discussed in terms of the hydrogen reduction mechanism

Designed Mesoporous Architecture by 10–100 nm TiO₂ as Electron Transport Materials in Carbon-Based Multiporous-Layered-Electrode Perovskite Solar Cells

Fully printable carbon-based multiporous-layered-electrode perovskite solar cells (MPLE-PSCs) are easy to fabricate and have excellent durability. In this study, the porosity of the mesoporous TiO2 layer as the electron transport layer in MPLE-PSCs was controlled by varying the particle diameter of TiO2 nanoparticles from 14 nm to 98 nm. Furthermore, the results of absorbed photon-to-current conversion efficiency, visible light reflectance spectroscopy, pore-size distribution, X-ray diffraction, field emission scanning electron microscopy, and photovoltaic parameters of MPLE-PSCs are discussed. Although the porous TiO2 layer with smaller nanoparticles showed higher photoabsorption, it was found that the more voids of perovskite crystals created in the TiO2 porous layer, the smaller the particle size (2 layers with particles over 26 nm are well filled with perovskite crystals, resulting in a higher photovoltaic capacity with TiO2 particles over 26 nm. As a result, the short-circuit current density (JSC) showed a maximum value using 43 nm TiO2 particles, with an average power conversion efficiency (PCE) of 10.56 ± 1.42%. Moreover, the PCE showed a maximum value of 12.20% by using 26 nm TiO2 nanoparticles

Superstoichiometric hydride PdHx ≤ 2 formed by electrochemical synthesis: Dissolution as molecular H2 proposed

H/Pd比が1を超えるPdの水素化物を電気化学法により合成した。X線回折測定の結果、金属格子はfccを保っていることが明らかとなった。格子定数はx>1で水素組成の増加に対して減少することが分かった。Pd原子がH2で部分的に置換され、H2で専有された超多量空孔が生成していることが示唆された