A (Bi₂O₂)²⁺ layer as a significant carrier generator and transmission channel in CaBi₂Nb₂O₉ platelets for enhanced piezo-photo-catalytic performance

The low photocatalytic conversion efficiency, poor light absorption and high charge recombination rate of traditional semiconductor photocatalysts continues to be a significant research challenge. In this paper, by combining detailed experimental and modeling techniques, we report on the unique potential of CaBi2Nb2O9 (CBN) platelets that can couple both piezo- and photo- multi-field effects to overcome these issues and realize high-efficiency hydrogen production and dye degradation. The surface adsorption of OH− and dye molecules is improved as a result of the built-in electric field, thereby demonstrating an enhanced piezo- and photo-catalytic H2 production activity, with a high rate of 96.83 μmol g−1 h−1. The piezo-photocatalytic decomposition ratio for 100 mL RhB dye of 10 mg/L can reach up to 98.7 % in 32 min using only 0.05 mg of CBN platelets (k = 0.131 min−1). It is shown that the careful introduction of regularly arranged layers of (Bi2O2)2+ into the CBN platelet structure provides a high transport of photoelectrons via a pathway of (Bi2O2)2+ → (CaNb2O7)2− → CBN surface. The electron density distribution of Bi atoms is also found to be enriched on the facets of (020) and (200) crystal planes in the CBN platelets, which is beneficial to the oxidation reduction reaction. Furthermore, the large deformation of CBN platelet during the application of ultrasound leads to an increase of the piezo-induced built-in electric field to improve charge separation and migration. This work therefore provides a new perspective in the design and manufacture of advanced materials with enhanced piezo- and photo-catalytic performance by exploiting multi-field coupling effects.</p

Study of Microstructure Regulation and In Situ Tensile Performance of Ni-Al Films

In this paper, Ni-Al films were prepared using magnetron sputtering technology. The microstructure of the films and the relationship between the residual stress and the adhesion strength were studied. More importantly, the mechanical strength–ductility properties of Ni-Al films were evaluated by in situ tensile testing. The results showed that the film mainly consisted of Ni3Al phase and Ni-based solid solution at the low power of Al target. The phase transition occurred, and the NiAl phase appeared when the Al sputtering power was increased. The complex structure, with the coexistence of Ni-based solid solution, Ni3Al, and NiAl phases, possessed increased residual stress and reduced adhesion strength. Meanwhile, the crack was easily penetrated through the inside and outside of the film, falling off during in situ tensile testing. While the small residual stress and large adhesion strength were obtained, only Ni3Al and NiAl coexisted, and the film fell off with difficulty. When the Al sputtering power was 400 W, the film showed the largest adhesion strength and the smallest residual stress. The best comprehensive performance was achieved with a tensile strength of 854 MPa and a yield strength of 90 MPa. The Al content of the film was up to 23.03 at.%, which was beneficial to the application and performance improvement of the film in molten salt corrosion resistance

Evolution of Structure and Properties of Micro-Nano Structure 2507 Duplex Stainless Steel Prepared by Aluminothermic Reduction

In this work, a large ingot of micro-nano structure 2507 duplex stainless steel was prepared in a single step using the aluminothermic reaction method. Chromium having different excess fractions were added to reaction powders to make up for evaporation loss, and the results show that the composition and structure of 2507 duplex stainless steel with a chromium excess ratio of 70% are satisfactory. The volume fraction of nanocrystalline in as-cast alloy was 41% and the average grain size was 34 nm. Additionally, the anticipated steels were rolled roughly with deformation of 40% at 1000 °C and followed by fine rolling with deformation of 30, 50 and 70%, separately, at 800 °C. Then, the effects of rolling deformation and precipitation on mechanical properties were studied in detail. Compared with the as-cast alloy, there was no phase transformation in the alloys with deformation of 30 and 50%, and they were still composed of γ and α phases, whereas the σ phase appeared in the alloy with deformation of 70%. When the deformation was 50%, the rolled alloy achieved the best performance, and the tensile strength, yield strength, and elongation were 912 MPa, 523 MPa, and 24.3%, respectively

Evolution of Structure and Properties of Micro-Nano Structure 2507 Duplex Stainless Steel Prepared by Aluminothermic Reduction

In this work, a large ingot of micro-nano structure 2507 duplex stainless steel was prepared in a single step using the aluminothermic reaction method. Chromium having different excess fractions were added to reaction powders to make up for evaporation loss, and the results show that the composition and structure of 2507 duplex stainless steel with a chromium excess ratio of 70% are satisfactory. The volume fraction of nanocrystalline in as-cast alloy was 41% and the average grain size was 34 nm. Additionally, the anticipated steels were rolled roughly with deformation of 40% at 1000 &deg;C and followed by fine rolling with deformation of 30, 50 and 70%, separately, at 800 &deg;C. Then, the effects of rolling deformation and precipitation on mechanical properties were studied in detail. Compared with the as-cast alloy, there was no phase transformation in the alloys with deformation of 30 and 50%, and they were still composed of &gamma; and &alpha; phases, whereas the &sigma; phase appeared in the alloy with deformation of 70%. When the deformation was 50%, the rolled alloy achieved the best performance, and the tensile strength, yield strength, and elongation were 912 MPa, 523 MPa, and 24.3%, respectively

Facile Synthesis of FeOOH Quantum Dots Modified ZnO Nanorods Films via a Metal-Solating Process

In this study, we referenced the formation principle of rust in nature and the FeOOH quantum dots (QDs) were prepared using a metal-solating process. The FeOOH QDs exhibited an average diameter of 3.5 nm with well crystallinity. Furthermore, the as-prepared FeOOH QDs were deposited on ZnO nanorods film as a co-catalyst for water oxidation. The crystal phase, microstructures, and optical properties of the synthesized films were established through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and ultraviolet–visible absorption spectroscopy (UV-vis). Applied as a photoanode for solar water splitting, the FeOOH QDs/ZnO nanorods film exhibited a photocurrent density of 0.44 mA/cm² at 1.23 V vs RHE, which is 2.1 times higher than that of pure ZnO film. After the loading of FeOOH QDs, the ZnO photoanode showed higher surface charge injection efficiency (by a factor of ∼2) and better long-term stability. The analysis of electrochemical measurements displayed that, as a co-catalyst of the oxygen evolution reaction, FeOOH QDs resulted in a noticeable cathodic shift of photocurrent onset potential for water oxidation and a remarkable improvement of surface charge injection efficiency. In addition, the metal-solating method can be applied to preparing the other metal oxides QDs, such as WO₃ and ZnO QDs