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The structural, electronic, optical, mechanical, lattice dynamics, and electronic transport properties of SrCu2O2 crystals were studied using first-principles calculations. The calculated band gap of SrCu2O2 using the HSE hybrid functional is about 3.33 eV, which is well consistent with the experimental value. The calculated optical parameters show a relatively strong response to the visible light region for SrCu2O2. The calculated elastic constants and phonon dispersion indicate that SrCu2O2 has strong stability in mechanical and lattice dynamics. The deep analysis of calculated mobilities of electrons and holes with their effective masses proves the high separation and low recombination efficiency of photoinduced carriers in SrCu2O2. [ABSTRACT FROM AUTHOR]

Selective recovery of indium has been widely studied to improve the resource efficiency of critical metals. However, the interaction and selective adsorption mechanism of indium/iron ions with tannin-based adsorbents is still unclear and hinders further optimization of their selective adsorption performance. In this study, the epigallocatechin gallate (EGCG) monomer, which is the key functional unit of persimmon tannin, was chosen to explore the ability and mechanism of selective separation/extraction of indium from indium–iron mixture solutions. The density functional theory calculation results indicated that the deprotonated EGCG was easier to combine with indium/iron cations than those of un-deprotonated EGCG. Moreover, the interaction of the EGCG–Fe(III) complex was dominated by chelation and electrostatic interaction, while that of the EGCG–In(III) complex was controlled by electrostatic interactions and aromatic ring stacking effects. Furthermore, the calculation of binding energy verified that EGCG exhibited a stronger affinity for Fe(III) than that for In(III) and preferentially adsorbed iron ions in acidic or neutral solutions. Further experimental results were consistent with the theoretical study, which showed that the Freundlich equilibrium isotherm fit the In(III) and Fe(III) adsorption behavior very well, and the Fe(III) adsorption processes followed a pseudo-second-order model. Thermodynamics data revealed that the adsorption of In(III) and Fe(III) onto EGCG was feasible, spontaneous, and endothermic. The adsorption rate of the EGCG monomer for Fe(III) in neutral solution (1:1 mixed solution, pH = 3.0) was 45.7%, 4.3 times that of In(III) (10.7%). This study provides an in-depth understanding of the relationship between the structure of EGCG and the selective adsorption capacity at the molecular level and provides theoretical guidance for further optimization of the selective adsorption performance of structurally similar tannin-based adsorbents. [ABSTRACT FROM AUTHOR]

Electronic structure, optical, mechanical, and lattice dynamical properties of the tetragonal MgBi2O6 are studied using a first-principles method. The band gap of MgBi2O6 calculated from the PBE0 hybrid functional method is about 1.62 eV and agrees well with the experimental value. The calculations on elastic constants show that MgBi2O6 exhibits mechanical stability and strong elastic anisotropy. The detailed analysis of calculated optical parameters and effective masses clearly indicate that MgBi2O6 has strong optical response in the visible light region and high separation efficiency of photoinduced electrons and holes. [ABSTRACT FROM AUTHOR]

Electronic structure, thermodynamics, and thermoelectric properties of β -BaCu 2 S 2 with naturally layered structure have been systematically investigated by using first-principles calculations and the Boltzmann transport theory. Our calculated results show that the Ba–S bonding interactions play an important role in determining the structural stability of β -BaCu 2 S 2 considering the Cu–S and Cu–Cu antibonding states at the top of valence band. Thermoelectric transport properties of β -BaCu 2 S 2 are significantly anisotropic depending on the crystallographic orientation. The slow carrier mobility, especially that along the c axis, would be responsible for its relatively low thermoelectric figure of merit. Metal doping is expected to be an effective route to improve the thermoelectric properties of β -BaCu 2 S 2 significantly through enhancing its electrical conductivity. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement causes deterioration of materials used in metal–hydrogen systems. Alloying is a good option for overcoming this issue. In the present work, first-principles calculations were performed to systematically study the effects of adding Ni on the stability, dissolution, trapping, and diffusion behaviour of interstitial/vacancy H atoms of pure V. The results of lattice dynamics and solution energy analyses showed that the V–Ni solid solutions are dynamically and thermodynamically stable, and adding Ni to pure V can reduce the structural stability of various VHx phases and enhance their resistance to H embrittlement. H atoms preferentially occupy the characteristic tetrahedral interstitial site (TIS) and the octahedral interstitial site (OIS), which are composed by different metal atoms, and rapidly diffuse along both the energetically favourable TIS → TIS and OIS → OIS paths. The trapping energy of monovacancy H atoms revealed that Ni addition could help minimise the H trapping ability of the vacancies and suppress the retention of H in V. Monovacancy defects block the diffusion of H atoms more than the interstitials, as determined from the calculated H-diffusion barrier energy data, whereas Ni doping contributes negligibly toward improving the H-diffusion coefficient. [ABSTRACT FROM AUTHOR]

Heterostructured AgBr/Bi 2 Sn 2 O 7 photocatalysts were synthesized successfully via the ultrasonic-assisted chemical precipitation method. XRD, FT-IR, FE-SEM, TEM, XPS, UV–vis-DRS and PL spectroscopy were used to characterize the phase structure, morphology, chemical composition, oxidation state, and optical properties of AgBr/Bi 2 Sn 2 O 7 heterojunction. The photocatalytic activity of as-prepared catalysts was evaluated by the degradation of RhB under visible light irradiation. The obtained AgBr/Bi 2 Sn 2 O 7 composite with the 1:1 molar ratio exhibited significantly enhanced photocatalytic performance. Further first-principles calculations indicated that the hybridization interaction between Ag and O atoms at AgBr/Bi 2 Sn 2 O 7 interface is expected to be beneficial for enhancing the charge transfer and improving the photocatalytic activity of heterostructured composites. [ABSTRACT FROM AUTHOR]