Directed energy deposition (DED) is suitable for fabrication of large Inconel 718 components, however, large columnar dendrites and several laves phase impair the mechanical properties. In this work, the formation mechanism of heterostructure microstructure with coarse grain (CG) and fine grain (FG) alternating distribution was explored, and the evolution process of Laves phase during inter-layer hammering hybrid directed energy deposition (HDED) was revealed. The results show that the heterostructure microstructure composed of CG region and FG region with a ratio of 1:1 was obtained due to the work hardening and recrystallization mechanisms, and the average grain size of CG region and FG region are 68.9 μm and 12.0 μm, respectively. The Laves phase was first fractured into small pieces by hammering and then resolved into the matrix during the subsequent heat input process, which promotes the precipitation of γ″ phase from the matrix. The strength and plasticity of the specimens f
Anion exchange membrane water electrolyzers (AEMWEs) feature compelling advantages over the current benchmarking proton exchange membrane water electrolyzers (PEMWEs). However, the sluggish hydrogen evolution kinetics in alkaline media and its elusive mechanism, greatly impede the practical deployment of AEMWEs. A clear understanding of alkaline hydrogen evolution reaction (HER) mechanism is a prerequisite to design advanced electrocatalysts for AEMWEs. High-performance alkaline HER electrocatalysts have been extensively reported, but most of these development practices are at the trial-and-error stage. Herein, we contribute an in-depth review of alkaline HER by integrating mechanistic and theoretical understanding of alkaline hydrogen evolution into a series of classical catalyst design cases, with special focus on the critical role of interface chemistry in tailoring the intrinsic activity of platinum group metal-based heterostructured electrocatalysts, aiming to provide a solid guid
Room-temperature sodium-sulfur (RT Na-S) batteries are considered to be a competitive electrochemical energy storage system, due to their advantages in abundant natural reserves, inexpensive materials, and superb theoretical energy density. Nevertheless, RT Na-S batteries suffer from a series of critical challenges, especially on the S cathode side, including the insulating nature of S and its discharge products, volumetric fluctuation of S species during the (de)sodiation process, shuttle effect of soluble sodium polysulfides, and sluggish conversion kinetics. Recent studies have shown that nanostructural designs of S-based materials can greatly contribute to alleviating the aforementioned issues via their unique physicochemical properties and architectural features. In this review, we review frontier advancements in nanostructure engineering strategies of S-based cathode materials for RT Na-S batteries in the past decade. Our emphasis is focused on delicate and highly efficient desig
The design of two-dimensional (2D) heterostructures (HSs) is an effective method to tune the physical and chemical properties of 2D materials. Using first-principles calculations, we explore the photocatalytic activity of CdS/PtSSe HSs (CPHSs) including CdS/SPtSe HSs (CPHS(S)s) and CdS/SePtS HSs (CPHS(Se)s). The small lattice mismatches and the negative interface formation energies suggest that the CPHSs are feasible, and the small bandgaps guarantee the CPHSs to absorb sufficient visible light. The stacking configurations can hardly affect the electronic structures of CPHS(S)s and CPHS(Se)s, but the contact sides can switch CPHSs between type-I and type-II. The type-I CPHS(Se)s are potential candidates as light-emitting diodes. For the CPHS(S)s, the type-II band alignments promote the spatial separation of photogenerated carriers, and the induced built-in electric fields around the interface region also promote the separation of photoinduced carriers. In addition, the band edges of CP
In this study, BiNbO4 nanoplates were successfully synthesized by the molten salt's method. The morphology, crystalline structure, optical and photocatalysis properties were investigated in detail. The crystal structure and micrographs results confirm the existence of polymorph heterostructure and nanoplates like morphology of materials. The photocatalysis results show that the samples exhibit high performance toward decolorating two dyes and also phenol. The methylene orange and Rhodamine B were completely decolored within 80 min under-stimulated light. After 120 min, 20% of the phenol was photodegraded. The results indicated that BiNbO4 nanoplates have superior photocatalytic performance and appropriate conduction and valence band position. The design strategy that can control the morphology of BINbO4 has led to another route of synthesis; the method of synthesis has resulted in environmentally friendly materials that are suitable for photodegradation of pollutants and water spl