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Pt 2 Ga and Pd 2 Ga monolayers are high-efficiency multifunctional electrocatalytic materials. [Display omitted] • We theoretically report two novel 2D electrocatalysts with low Pt loading. • The HER activity of Pd 2 Ga monolayer is higher than that of currently commercialized Pt. • Pt 2 Ga monolayer possesses extremely lower overpotentials for OER and ORR, which can act as high-performance multifunctional electrocatalysts. • We provide an effective guidance for the rational design of multifunctional electrocatalysts. Developing multifunctional electrocatalysts with high performance for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is still a challenging task. In this work, the electrocatalytic activities of Pt 2 Ga and Pd 2 Ga monolayers are systematically investigated based on first-principles calculations. The high dynamic and thermal stabilities of Pt 2 Ga and Pd 2 Ga monolayers are confirmed by phonon dispersion calculations and ab initio molecular dynamics (AIMD) simulations, respectively. In addition, the Pd 2 Ga free energy for H adsorption is predicted to be −0.03 eV, implying its extremely high activity for HER. Furthermore, the Pt 2 Ga overpotential for OER and ORR are estimated to be 0.48 and 0.42 V, correspondingly, indicating its high catalytic performance. This work provides adequate guidance for designing multifunctional electrocatalysts with high performance for OER, ORR and HER. [ABSTRACT FROM AUTHOR]

[Display omitted] The reactions of the γ-U (0 0 1) and (1 1 0) surfaces in contact with O 2 were investigated by density functional theory (DFT), ab initio thermodynamic methods and ab initio molecular dynamics simulations (AIMD). The adsorption of the O atom and O 2 molecule on the (0 0 1) and (1 1 0) surfaces and subsurface are first studied, which provides insights into the adsorption, dissociation, and diffusion of O 2 on the surfaces. Furthermore, the effects of coverages on surface adsorption are considered to help us further understand surface oxidation corrosion. Based on the above research, we can speculate on the initial process of surface corrosion: 1. O 2 molecules in the atmosphere first approach the U surface in the form of physical adsorption; 2. O 2 molecules dissociate into O atoms on the surface; 3. O atoms diffuse on the surface after overcoming a small energy barrier and eventually occupy hollow (H) sites; 4. O atoms penetrate from the H sites to the subsurface; 5. The diffusion of O atoms inside the metal is more likely to be carried out by octahedral interstitial sites. Moreover, the adsorption phase diagrams indicate that O 2 will readily react with U even under ultra-high vacuum conditions, which is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] Mayenite (12CaO · 7Al 2 O 3 or generally named C12A7) and its electride form (C12A7 : 4 e −) have drawn intensive attention because of a variety of promising applications including display devices, catalysis, and transistors. C12A7 is a transparent insulator and it can be controllably engineered to a conductor or superconductor upon introducing oxygen vacancies and substitutional anionic impurities. However, the influence of external pressure on electronic and optical properties of C12A7 remains intriguingly less explored. On the basis of the density functional theory (DFT) and ab initio molecular dynamics, this work presents the variations of electronic and optical properties of C12A7 via the immense external pressure. The findings reveal that the applied pressure induces the structural deformation until it is energetically amorphised at pressure greater than 17.94 GPa. Such deformation consequently creates the gradual reduction in the electronic band gap because of the intensified overlap of electronic bands among the framework Ca-3 d , O-2 p , and the in-cage extra-framework O-2 p states. Furthermore, the drop in the band gap yields the remarkable enhancement in the optical absorbance in the visible and UV regions. Our findings unveil the underlying influences of the external pressure on the C12A7 properties which are of fundamental interests and functional design for applications. [ABSTRACT FROM AUTHOR]