performance and low price for working in alkaline solution.Ruthenium, as a member of platinumgroup metals with 1/30 price of Pt, [14] has been proved to be a promising catalyst for HER in alkaline solution due to its high efficiency on water dissociation, [15][16][17][18] however, the strong interaction between Ru and H atoms impedes the subsequent hydrogen evolution because of the well-known scaling relationship for heterogeneous catalysts. [17,[19][20][21] Many efforts had been devoted to constructing Rubased heterostructures (e.g., Ru/carbon quantum dots, [22] Ru/C 2 N, [18] RuCo/ nitrogen-doped graphene, [23] fcc-Ru/ C 3 N 4 /C, [17] Ru/nitrogen-doped carbon, [24] Ru/graphene [25] ), which show great advantages on promoting water dissociation by synergistic effect. Nevertheless, less attention was paid on the improvement of hydrogen adsorption. Recently, singleatom alloys (SAAs), which comprise separated solute atoms in metallic matrix, show great potential on circumventing scaling relationships. [23,26,27] meanwhile, the interaction between the solute atoms and matrix can modify their electronic structure, [26,28,29] leading to a suitable adsorption energy for hydrogen. Consequently, constructing Ru-based SAAs opens a new avenue toward high HER performance.Herein, we reported the synthesis of RuAu SAAs through a laser ablation in liquid (LAL) technique, which possesses strong quenching effect so as to fabricate metastable nanostructures with novel properties. [30,31] We choose Au as the alloying element on the basis of the following considerations: First, Au is known as an inert metal with weak hydrogen adsorption thus can counteract the strong hydrogen adsorption of Ru matrix. Second, the immiscibility between Au and Ru may create a unique geometric and electronic structure in RuAu SAAs. [32,33] Finally, chemically inert Au favors long-term durability during the reaction. As such, the as-prepared RuAu catalyst exhibits a low overpotential, 24 mV@10 mA cm −2 , which is much lower than Pt/C (46 mV@10 mA cm −2 ) in alkaline media. Moreover, the turnover frequency (TOF) of RuAu SAAs is three times that of the Pt/C catalyst. Density functional theory (DFT) computation reveals that the high performance originates from the relay catalysis of Ru host (for water dissociation) and Au dopant (for hydrogen evolution). To the best of our knowledge, this is the first report on the synthesis of RuAu SAAs with outstanding HER performance in alkaline media. Furthermore, the idea of the mixing immiscible metallic elements by LAL can be facilely Highly efficient and stable catalysts for the hydrogen evolution reaction, especially in alkaline conditions are crucial for the practical demands of electrochemical water splitting. Here, the synthesis of a novel RuAu single-atom alloy (SAA) by laser ablation in liquid is reported. The SAA exhibits a high stability and a low overpotential, 24 mV@10 mA cm −2 , which is much lower than that of a Pt/C catalyst (46 mV) in alkaline media. Moreover, the turnover frequency of RuAu SAA is th...

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The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1 -x)Ba 0.70 Ca 0.30 TiO 3 -xBiFeO 3 [(1 -x)BCT-xBF, x = 0-0.90] solid solutions have been systematically investigated. The ceramics have coexisted tetragonal (T) and orthorhombic (O) phases when x ≤ 0.06, coexisted pseudocubic (PC) and O phases when x = 0.065, coexisted cubic and O phases when 0.07 ≤ x ≤ 0.12, PC phase when 0.21 ≤ x ≤ 0.42, coexisted T and rhombohedral (R) phases when 0.52 ≤ x ≤ 0.70, and R phase when x ≥ 0.75. Significantly, composition-dependent microstructures and Curie temperature are observed, the average grain size increases from 1.9 lm for x = 0, reaches 12.0 lm for x = 0.67, and then decreases to 1.3 lm for x = 0.90. At room temperature, the ceramics with x = 0.42-0.70 show piezoelectric properties and multiferroic behaviors, characterized by the polarization-electric field, polarization current intensityelectric field, and magnetization-magnetic field curves, the composition with x = 0.67 has maximum polarization, remnant polarization, maximum magnetization, and remnant magnetization of 15.0 lC/cm 2 , 9.1 lC/cm 2 , 0.33 emu/g, and 0.14 emu/ g, respectively. In addition, the magnetocapacitance is evidenced by the increased relative dielectric constant with increasing the applied magnetic field (H). With DH = 8 kOe, the composition with x = 0.67 shows the largest values of (e r (H) -e r (0))/e r (0) = 2.96% at room temperature. The structure-property relationship is discussed intensively.

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Li, Ta modified (K,Na)NbO3 single crystals with the size of 18 mm × 18 mm × 10 mm were successfully grown by top-seeded solution growth method, with orthorhombic–tetragonal phase transition temperature ~79 °C and Curie temperature ~276 °C. The electromechanical coupling factors k33 and kt were found to be ~88% and ~65%, respectively. The piezoelectric coefficient d33 for the [001]c poled crystals reached 255 pC/N. In addition, the electromechanical coupling factor exhibited high stability over the temperature range of −50 °C to 70 °C, making these lead free crystals good candidates for electromechanical applications.

Polymer composite foams are desirable materials for electromagnetic (EM) energy attenuation. However, a number of challenges limit improvement in the EM energy attenuation properties of foams. In this study, a simple microcellular injection molding method was used to fabricate highly compressible thermoplastic urethane (TPU)/carbon nanotube (CNTs) composite foams, which also had increased conductivity with an increase in CNT content. Compared to unfoamed composites, foamed composites exhibited higher conductivity and EM attenuation properties because of the presence of a microcellular structure. Moreover, the TPU/CNT foam with 4 wt % CNTs (F(4)) demonstrated strong EM dissipation and an optimal reflection loss (RL) value of −30.4 dB. Furthermore, stimulated by thermal heating and cyclic compression, EM attenuation was observed to increase because of the higher conductivity. Note that F(4) foam having a small thickness of 1.3 mm when treated at 333 K had the highest EM dissipation and the lowest RL value of −51.8 dB. Enhanced polarization and ohmic losses and multiscattering were responsible for the increased EM absorption. This behavior is attributed to the movement of CNTs within the TPU elastomer walls via thermal or compression stimulation. For designing stimulation-dependent multifunctional materials, composite foams with response to thermal heating were proved to be an alternative approach.