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• Cu-MOF is used to recycle Au(S 2 O 3) 2 3− from alkaline leachate for the first time. • The adsorption capacity of 206.19 mg/g is the highest in the adsorption method. • Diphenylamine and copper cluster defects are used as active sites. • Local exotherms of DMF facilitate the recovery of Au(S 2 O 3) 2 3−. • The interaction between Cu-ADA and Au(S 2 O 3) 2 3− was investigated with DFT calculation. Recycling gold from electronic waste is essential for environmental protection and resource sustainability. However, the design of adsorbents for effective recycling of Au(S 2 O 3) 2 3− from alkaline leach solutions is of great challenge and has not been investigated by using MOFs. Herein, we report the design and preparation of a Cu-MOF based on the structural characteristics of Au(S 2 O 3) 2 3−, which is constructed by 4,4′-di carboxy diphenylamine and Cu 2 -paddlewheel. Cu-ADA-53 demonstrates ultra-high adsorption capacity of 206.19 mg g -1, and the gold recovery in actual alkaline leach solutions is more than 99 %. X-ray photoelectron spectroscopy, thermodynamic study, and density functional theory calculations reveal the excellent performance of Cu-ADA-53 for Au(S 2 O 3) 2 3− results from the abundant Lewis base diphenylamine groups and open copper sites. More importantly, different from pore diffusion-promoting adsorption, the axial coordination DMF of Cu 2 -paddlewheel fell off into the water phase and then released heat locally at the adsorption sites. The local exotherms increase the temperature of the adsorption sites, further promoting the adsorption of Au(S 2 O 3) 2 3− by Cu-ADA-53. The local exotherms at adsorption sites provide a novel insight to efficiently recover Au(S 2 O 3) 2 3−. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we studied the geography and electronic structure of CoSi2 and the stability of CoSi2 (110) films with thickness from 1 to 25 monolayers by first- principles calculation under the frame of the density functional theory (DFT). The results represent that the stability of the films oscillate with the thickness with a period of 4 monolayers (MLs), and the amplify decay with the thickness, which present the modulation of quantum size effects (QSEs) on the growth of transition metal silicides (TMSs) films and can be explained well by the consequent electronic structure. This work represents the thickness dependence for the early stage growth of TMSs films; uncover the underlying mechanism of the QSEs, which is meaningful for the growth of stable and union TMSs films to increase the properties of electronic devices. [ABSTRACT FROM AUTHOR]

Density functional theory calculations including dispersion correction (DFT-D2) were used to investigate the relationship between charge distribution and nanofriction characteristics of graphene-based material systems. In our calculations, the single-side-hydrogenated graphene (SSHGraphene) system exhibits lower coefficient of friction, whereas the graphane system exhibits larger one compared with graphene system. These results are attributed to the adjustments of interfacial charge distribution that are induced by different hydrogen passivations. The charge distribution is smooth along the sliding direction for the SSHGraphene sheet, which yields a small potential barrier. Corrugation of the charge distribution in graphane system is much steeper than that in graphene system, which leads to a larger potential barrier. Comparative investigations reveal that the interfacial charge distributions determine the nanofriction performance, which may be helpful for friction modulation and design of new controlling lubricant material. [ABSTRACT FROM AUTHOR]

The interfacial friction performances of graphene covered and hydrogen-terminated diamond surfaces were investigated comparatively by first-principles calculations within density functional theory (DFT). Both systems exhibit similar excellent lubricating effects under small load, but the graphene covered interface presents small friction than that of hydrogenated system for the larger load. The calculated interfacial friction between two sheets of graphene covered diamond surface increases slowly than that of hydrogenated system in a wide range of pressure scale, and the friction difference between the two systems increases with increasing external pressure, indicating that graphene has flexible lubricating properties with high load-carrying capacity. This behavior can be attributed to the large interlayer space and a more uniform interlayer charge distribution of graphene covered diamond interface. Our investigations suggest that graphene is a promising candidate as solid lubricate used in diamond film, and are helpful for the understanding of interfacial friction properties of diamond film. [ABSTRACT FROM AUTHOR]

Dispersion-corrected density functional theory (DFT) calculations reveal that the layered electride of dicalcium nitride (Ca2N) exhibits stronger interlayer binding interactions but lower interlayer friction behavior than that of traditional layered lubricants weakly bonded by van der Waals (vdW) interactions, such as graphite, h-BN, and MoS2. These results are attributed to the two-dimensional (2D) homogeneous conduction electrons distribution in the middle of the interlayer space of Ca2N, which yields a smooth sliding barrier and hence ultralow friction behavior. The interesting results obtained in this study have not only broadened the scope of 2D solid lubricants but also enriched the physical understanding of ultralow friction mechanism for 2D systems. [ABSTRACT FROM AUTHOR]