Achieving high photocatalytic activity with the lowest possible platinum (Pt) consumption is crucial for reducing the cost of Pt-based cocatalysts and enabling large-scale applications. Bimetallic Ni-Pt cocatalysts exhibit excellent photocatalytic performance and are considered one of the most promising photocatalysts capable of replacing pure Pt for hydrogen evolution reaction (HER). However, the synergistic photocatalytic mechanism between bimetallic Ni-Pt cocatalysts needs to be further investigated. Herein, we deposit highly dispersed Ni-Pt bimetallic cocatalysts on the surface of TiO2 by radiolytic reduction. We study the dynamics of photogenerated charge carriers of the Ni-Pt-comodified TiO2 and propose their underlying electron transfer mechanisms, in which Pt acts as an electron trap, whereas Ni serves as an electron supplier. The synergistic effect is Ni/Pt ratio-dependent and can confer bimetallic Ni-Pt to pure Pt-like photocatalytic activity in HER. The Ni2-Pt1-comodified TiO2 is optimized to be the most cost-effective photocatalyst with robust stability, which exhibits about 40-fold higher performance than bare TiO2.

Versatility of powder metallurgy was used to design new duplex and compositionally graded steels. Rapid consolidation by Spark Plasma Sintering (SPS) and longer consolidation by Hot Isostatic Pressing (HIP) were applied on two austenitic 316L and martensitic Fe-9Cr powders, either homogeneously blended or uniaxially graded before sintering.The microstructural investigations by micro-hardness, SEM, EDX and EBSD showed a continuous crystallographic structure at the austenite–martensite interface and a similar grain size in SPS and HIP samples, whereas a larger interdiffusion length of Cr and Ni was observed in the HIP sample, as confirmed by diffusion calculations. The tensile behaviour of materials could not be described by a simple law of mixtures. To better understand this phenomenon, the obtained materials were described as a composite and iso-strain and iso-stress models were used and discussed. The microstructural characterizations show that during the consolidation, diffusion of the chemical species modifies the nature and the respective fractions of phases, which explains the discrepancy between the models and the experimental mechanical behaviour of the duplex alloys.

The effects of deformation and stress on the surface and grain boundary oxidation of Alloy 600, exposed to primary water of Pressurized Water Reactors (PWRs), were investigated by Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Scanning Electron Microscopy (SEM). It was found that tensile straining prior to oxidation does not modify the surface oxide thickness while the intergranular oxide depth increases when the strain reaches a critical value of 15%. The oxide growth rates at surface and grain boundaries are enhanced under stress. The effect of stress is more significant when the specimen is under elastic strain than plastically deformed.

The impact toughness and fracture toughness properties at room temperature of 316L austenitic stainless steel manufactured by laser powder bed fusion were determined and compared. The effect of the grain size and morphology, of the dislocation structures and of the oxide nanoparticles on the toughness behavior was systematically investigated. In all cases, ductile fracture resulted from decohesion at the matrix/oxide interfaces. After a stress-relief heat treatment, Charpy absorbed energy and fracture toughness at crack initiation were 170–250 J/cm2 and 350–550 kJ/m2, respectively. Dislocation recovery has no significant influence on the toughness properties. Recrystallization decreased the impact toughness and fracture toughness by up to 25% and 50% respectively, due to synergistic effects between recrystallization and oxide particle coarsening, resulting in coarse oxides located along recrystallized grain boundaries that facilitated ductile cracking. Whatever the as-built microstructure and the heat treatment, fracture and impact toughness obeyed a linear correlation with an accuracy of ±20%. They were also linearly correlated for each of the crack initiation and crack propagation stages.

Dielectric capacitors with an ultrahigh power density have received extensive attention due to their potential applications in advanced electronic devices. However, their inherent low energy density restricts their application for miniaturization and integration of advanced dielectric capacitors. Herein, a novel composite entirely incorporated with two-dimensional (2D) nanosheets with a topological trilayered construction is prepared by a solution casting and hot-pressing method. The 2D boron nitride nanosheets (BNNS) with a wide band gap that are oriented in a poly(vinylidene fluoride) (PVDF) matrix to form the upper and bottom outer layers would efficiently suppress the leakage current in composites, thus significantly improving the overall breakdown strength. Meanwhile, the 2D anatase-type TiO2 nanosheets (TONS) uniformly distributed in the middle layer can enhance their interfacial compatibility and polarization with the PVDF matrix, leading to a synergistic improvement in both the breakdown strength and dielectric constant of the composite. In particular, a significantly improved dielectric constant of ∼11.42, a reduced dielectric loss of 0.03 at 100 Hz, and a maximum discharge energy density (Udis) of 10.17 J cm-3 at an electric field of 370.1 MV m-1 can be obtained from the trilayered composite containing 3 wt % 2D TONS in the middle layer and 2 wt % 2D BNNS on the outer layer. The finding of this research offers an effective strategy for the preparation of advanced polymer-based composites with an outstanding discharge energy density performance.

• Comparison and dynamically fractured samples in 1 or 2 impacts. • Double impact reduces scatter with statistical significance. • Double impact may lead to higher fracture stress. The effects of dynamic predeformation on the dynamic behaviour of metallic glasses (MG) are investigated through split Hopkinson pressure bar (SHPB) tests. The results obtained on samples fractured in a single test are compared with those on samples fractured in two successive SHPB tests. They show a reduction in data scatter and an increase in maximum stress for predeformed samples.

In this study, the recrystallization kinetics of two 316 L stainless steels produced by Laser Powder-Bed Fusion (LPBF) were compared. The as-built microstructures of the studied materials differed by their grain size, their grain boundary character distributions, and their populations of nanoprecipitates. Strong differences in their recrystallization kinetics were observed; they were attributed to a delayed nucleation in the steel exhibiting the finer grains, the lower density of low-angle boundaries (LAB), and the higher volume fraction of precipitates. This work shows that a high density of LABs stemming from the solidification stage in the LPBF process promotes recrystallization by locally increasing the stored energy close to grain boundaries, and hence the formation of recrystallization nuclei. The design of low-LAB microstructures could thus lead to higher stability at high temperatures. • Recrystallization kinetics are heavily influenced by the as-built microstructure. • Kinetics are not affected by a second-phase particles volume fraction increase. • Low angle boundaries promotes the formation of recrystallization nuclei.

Due to their feature of the conversion from electrical to mechanical energy under an applied electric field, dielectric elastomers (DEs) have been widely adopted in smart devices. However, the significant electro-actuated property of DEs is always obtained under a giant driving electric field, which raises a potential safety hazard and limits their practical application range. Moreover, the traditional strategy of regulating the flexibility of DEs via physical swelling effect would result in an undesired plasticizer leakage and an irreversible reduction in both electromechanical stability and lifetime. Herein, a typical heterogeneous multi-layered polydimethylsiloxane (PDMS)-based DE composite was prepared by solution blending and the layer-by-layer casting method. Through synchronously introducing the high-permittivity BaTiO3 and the plasticizer dimethyl silicone oil in the middle layer, both the dielectric and mechanical property of the composite are effectively regulated. Not only the interlayered mechanical mismatch is eliminated but also the problem of plasticizer leakage is optimized through this reasonable structural design. The maximum electro-actuated strain obtained in the sandwiched DE composite was as large as 24.25% under 60 V/μm, which is 338.52% higher than that of pristine PDMS. Furthermore, the composite exhibits the largest driving strain (58.31%) near its breakdown electric field of 77.82 V/μm. Therefore, this study provides a promising route for the preparation of advanced DE composite with an improved low-field electro-actuated property.