Physical and chemical properties of Cu(I) compounds with O and/or H

The electronic structure and chemical bonding of Cu(I) compounds with O and/or H are investigated using ab initio calculations based on density functional theory. A hybrid functional PBE0 is employed, which accurately reproduces an experimental band gap of cuprite Cu2O. Cuprous hydroxide CuOH (cuprice) is found to be an indirect band gap semiconductor. Depending on the bond network configuration of CuOH, its band gap is found to vary between 2.73 eV and 3.03 eV. The presence of hydrogen in CuOH has little effect on the character of Cu–O bonds, as compared to Cu2O, but lowers the energy levels of the occupied states upon O–H bond formation. The bonding charge density and electron localization function calculations reveal that a closed-shell Cu–Cu interaction takes place in Cu2O and CuOH between the neighbouring Cu cations belonging to different bond networks. Besides, three structures of cuprous hydride CuH are investigated. We find that the halite structure of CuH can be stabilized at high pressure (above 32 GPa) while wurtzite is the most stable structure of CuH at ambient pressure. The H–H interaction contributes to the dynamical stabilization of the halite structure. The wurtzite and sphalerite structures of CuH are predicted to be semiconducting with small band gaps, while the halite structure is calculated to be metallic

Gamma radiation induces hydrogen absorption by copper in water

One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.Peer reviewe

Exploring configurational degrees of freedom in disordered solids

Recent computational modeling studies of configurational degrees of freedom in oxide-hydroxides of aluminum and copper are reviewed. Density functional theory calculations are employed to investigate the effect of hydrogen on the structural stability of gamma-alumina and to explore the configurational space of cuprous hydroxide CuOH. Free energy modeling, taking into account configurational and vibrational degrees of freedom, shows that the studied hydrogenated oxides of aluminum and copper are metastable compounds, whereas the respective oxides are thermodynamically stable phases. Selected structural and optical properties of the studied compounds, evaluated using a hybrid functional approach, are reported and compared with available experimental data