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Bimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts. [ABSTRACT FROM AUTHOR]

Abstract Bimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts.

When constructing a mathematical model describing the inelastic non-isothermal deformation of the inner wall of the cylindrical shell of the combustion chamber of a liquid-propellant rocket engine (LRE ЖРД), a simplified design scheme of a one-dimensional stress-strain state (SSS НДС) of a bimetallic shell was used. The analysis of changes in stresses and deformations in the inner and outer walls of the shell during the periods of start-up, operation, shutdown and pause between starts of a multiple-action LRE is carried out. To describe the inelastic deformation of the inner wall, a mechanical analogue is used, which makes it possible to describe the non-isothermal processes of plasticity and creep. An example of calculating the stress-strain state of a shell is given, which makes it possible to estimate the accumulation of the absolute value of inelastic deformation in the material of the inner wall, which affects the damageability of its material. [ABSTRACT FROM AUTHOR]

On the base of the simplified analytical model for the bimetallic shell of the combustion chamber of the reusable liquid-propellant rocket engine, the analysis of the loading of connectors between the shell walls and the accumulation of inelastic deformations in the inner wall material was carried out. The results obtained can be used for evaluation of the maximal number of engine operation cycles. [ABSTRACT FROM AUTHOR]

Conjugating plasmonic metals with catalytically active materials with controlled configurations can harness their light energy harvesting ability in catalysis. Herein, we present a well-defined core-shell nanostructure composed of an octahedral Au nanocrystal core and a PdPt alloy shell as a bifunctional energy conversion platform for plasmon-enhanced electrocatalysis. The prepared Au@PdPt core-shell nanostructures exhibited significant enhancements in electrocatalytic activity for methanol oxidation and oxygen reduction reactions under visible-light irradiation. Our experimental and computational studies revealed that the electronic hybridization of Pd and Pt allows the alloy material to have a large imaginary dielectric function, which can efficiently induce the shell-biased distribution of plasmon energy upon illumination and, hence, its relaxation at the catalytically active region to promote electrocatalysis.

Abstract: In this contribution, we discuss stress, deformation and stability conditions for thin double curved shallow bimetallic translation shells. According to the theory of the third order by the Czech researcher E. Chawalla, which takes into account the equilibrium of forces and moments acting on a deformed body and the supposition of large displacements, we present a system of three differential equations with boundary conditions for the description of displacements on the shell due to the temperature loading of the shell. The equations are based on the Kirchhoff hypothesis, on the supposition of moderate rotations and small strains of the shell element. [Copyright &y& Elsevier]

Abstract: This article considers the thermoelastic stability of bimetallic shallow shells of revolution. Basic equations are derived from Reissner’s non-linear theory of shells by assuming that deformations and rotations are small and that materials are linear elastic. The equations are further specialized for the case of a closed spherical cup. For this case the perturbated initial state is considered and it is shown that only in the cases when the cup edge is free or simply supported buckling under heating is possible. Further the perturbated flat state is considered and the critical temperature for buckling is calculated for the case of free and simply supported edges. The temperature–deflection diagrams are calculated by the use of the collocation method for shallow spherical, conical and cubic shells. [Copyright &y& Elsevier]

Abstract: The paper deals with stresses, strains and buckling conditions in the thin axi-symmetric shallow bimetallic shells with circular opening at the top of the shell. According to the third order theory by the Czech researcher E. Chawalla, which takes into account the equilibrium state of forces and moments acting on the deformed system, the paper presents a model for mathematical description of the system''s geometry, stresses, thermo-elastic strains and displacements. The mathematical formulation is based on the theory of large displacements. As an example, the results for spherical shallow shells are shown, approximated by a parabolic function. The shells are loaded with temperature and/or with load acting at the top of the shell or at the shell''s inner edge. The displacement state and the snap-through temperature are calculated numerically by the Runge Kutta algorithm of the fourth order, by non-linear shooting method. [Copyright &y& Elsevier]

The selective enhancement of catalytic activity is a challenging task, as catalyst modification is generally accompanied by both desirable and undesirable properties. For example, in the case of the direct synthesis of hydrogen peroxide, Pt on Pd improves hydrogen conversion, but lowers hydrogen peroxide selectivity, whereas Au on Pd enhances hydrogen peroxide selectivity but decreases hydrogen conversion. Toward an ideal catalytic property, the development of a catalyst that is capable of improving H-H dissociation for increasing H2 conversion, whilst suppressing O-O dissociation for high H2O2 selectivity would be highly beneficial. Pd-core AuPt-bimetallic shell nanoparticles with a nano-sized bimetallic layer composed of Au-rich or Pt-rich content with Pd cubes were readily prepared via the direct seed-mediated growth method. In the Pd-core AuPt-bimetallic shell nanoparticles, Au was predominantly located on the {100} facets of the Pd nanocubes, whereas Pt was deposited on the corners of the Pd nanocubes. The evaluation of Pd-core AuPt-bimetallic shell nanoparticles with varying Au and Pt contents revealed that Pd-core AuPt-bimetallic shell that was composed of 2.5 mol% Au and 5 mol% Pt, in relation to Pd, exhibited the highest H2O2 production rate (914 mmol H2O2 gmetal−1 h−1), due to the improvement of both H2O2 selectivity and H2 conversion. [ABSTRACT FROM AUTHOR]