Palladium diselenide (PdSe 2 ), a thus far scarcely studied group-10 transition metal dichalcogenide has exhibited promising potential in future optoelectronic and electronic devices due to unique structures and electrical properties. Here, the controllable synthesis of wafer-scale and homogeneous 2D PdSe 2 film is reported by a simple selenization approach. By choosing different thickness of precursor Pd layer, 2D PdSe 2 with thickness of 1.2-20 nm can be readily synthesized. Interestingly, with the increase in thickness, obvious redshift in wavenumber is revealed by Raman spectroscopy. Moreover, in accordance with density functional theory (DFT) calculation, optical absorption and ultraviolet photoemission spectroscopy (UPS) analyses confirm that the PdSe 2 exhibits an evolution from a semiconductor (monolayer) to semimetal (bulk). Further combination of the PdSe 2 layer with Si leads to a highly sensitive, fast, and broadband photodetector with a high responsivity (300.2 mA W −1 ) and specific detectivity (≈10 13 Jones). By decorating the device with black phosphorus quantum dots, the device performance can be further optimized. These results suggest the asselenized PdSe 2 is a promising material for optoelectronic application.

A detailed study aimed at understanding and confirming the reported highly promising performance of a La 0.3 Sr 0.7 Fe 0.7 Cr 0.3 O 3−δ (LSFCr) perovskite catalyst in CO 2 /CO mixtures, for use in reversible solid oxide fuel cells (RSOFCs), is reported in this work, with an emphasis on chemical and performance stability. This work includes an X-ray diffraction (XRD), thermogravimetric analysis (TGA), and electrochemical study in a range of pO 2 atmospheres (pure CO 2 , CO alone (balance N 2 ), and a 90−70% CO 2 /10−30% CO containing mixture), related to the different conditions that could be encountered during CO 2 reduction at the cathode. Powdered LSFCr remains structurally stable in 20−100% CO 2 (balance N 2 , pO 2 = 10 −11 −10 −12 atm) without any decomposition. However, in 30% CO (balance N 2 , pO 2 ∼ 10 −26 atm), a Ruddlesden−Popper phase, Fe nanoparticles, and potentially some coke are observed to form at 800 °C. However, this can be reversed and the original perovskite can be recovered by heat treatment in air at 800 °C. While no evidence for coke formation is obtained in 90−70% CO 2 /10−30% CO (pO 2 = 10 −17 −10 −18 atm) mixtures at 800 °C, in 70 CO 2 /30 CO, minor impurities of SrCO 3 and Fe nanoparticles were observed, with the latter potentially beneficial to the electrochemical activity of the perovskite. Consistent with prior work, symmetrical two-electrode full cells (LSFCr used at both electrodes), fed with the various CO 2 /CO gas mixtures at one electrode and air at the other, showed excellent electrochemical performance at 800 °C, both in the SOFC and in SOEC modes. Also, LSFCr exhibits excellent stability during CO 2 electrolysis in medium-term potentiostatic tests in all gas mixtures, indicative of its excellent promise as an electrode material for use in symmetrical solid oxide cells.

Due to the increasing desire for nanoscale optoelectronic devices with green light emission capability and high efficiency, ternary III‐N‐based nanorods are extensively studied. Many efforts have been taken on the planar device configuration, which lead to unavoided defects and strains. With selective‐area molecular‐beam epitaxy, new “Russian Doll”‐type InGaN/AlGaN quantum wells (QWs) have been developed, which could largely alleviate this issue. This work combines multiple nanoscale characterization methods and k∙p theory calculations so that the crystalline structure, chemical compositions, strain effects, and light emission properties can be quantitatively correlated and understood. The 3D structure and atomic composition of these QWs are retrieved with transmission electron microscopy and atom probe tomography while their green light emission has been demonstrated with room‐temperature cathodoluminescence experiments. k∙p theory calculations, with the consideration of strain effects, are used to derive the light emission characteristics that are compared with the local measurements. Thus, the structural properties of the newly designed nanorods are quantitatively characterized and the relationship with their outstanding optical properties is described. This combined approach provides an innovative way for analyzing nano‐optical‐devices and new strategies for the structure design of light‐emitting diodes.

After preparing samples (3mm long×4mm wide×36mm high) of Al2O3-MgAlON composites and sintered at 1500°C for 2 h in N2 atmosphere, samples’ cracks were carved by a Vickers hardometer’s pressing head on the center of the sample surface (4 mm×36 mm). Subsequently, the cracks were healed at 1000°C-1550°C for 6 h respectively. Effects of healing temperature on sample’s strength, crack healing dynamics and its molecular dynamics simulation were investigated. The results suggested that: the optimum range of cracks healing temperature was 1300°C-1550°C, and the healing process accelerated at 1300°C, meanwhile, the strength of samples increased significantly. Cracks completely healing finished at 1550°C. The dynamics equation of crack healing was lnν = -Q/kT+lnC. Through characterizing the crack healing rate with the recovering rate of sample’s strength, the diffusion activation energy Q = 4.264 × 10-30 J•K-1 and diffusion constant C=7.359 were claimed. The result of the molecular dynamics simulation suggested that cracks healing process was caused by diffusion could be divided into five stages: passivation of crack tips, formation of salient island, crack shrinkage, generation of secondary crack, and complete healing.

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