A direct and effective approach is proposed to fabricate bimetallic phosphide Ni 2 P−Cu 3 P with controllable phase composition and distribution for catalytic hydrogen evolution reaction (HER). Unlike previously reported precursors, a porous Ni−Cu alloy incorporated with graphitic carbon (NiCuC) prepared via powder metallurgy is employed herein, and the generated Ni 2 P−Cu 3 P@NiCuC possesses a hierarchical porous structure and controllable phase composition due to the high porosity and tunable Ni/Cu ratio of the precursor. With an optimal Cu content of 30.0 wt %, the catalyst demonstrates the highest catalytic activity due to a synergistic interaction between different metallic phosphide sites and the facilitated mass transport. Meanwhile, density functional theory (DFT) calculation reveals that the atomic interaction of Ni 2 P− Cu 3 P substantially lower the activation barrier for enhanced HER catalytic activity. The powder metallurgy provides an approach for the design of bimetallic phosphide electrocatalysts for HER and other catalytic applications.

Porous metals are of great interest as a potential engineering material in various industrial fields because of their unique properties such as their impact energy absorption capacity, their gas and liquid permeability, thermal conductivity, and electrical insulating properties.[1] However, their poor oxidation resistivity, poor corrosion resistance, and intolerance at elevated temperatures restrict their potential applications in much wider fields, such as high-temperature gas separation and as catalysis in rugged environments. It is well known that Ti-Al alloys are notable examples of intermetallic compounds containing a mixture of metallic and covalent bonds [2] that provide sound mechanical properties with outstanding corrosion resistance [3] and excellent oxidation resistance at elevated temperatures-particularly over 600°C. [4] In this Communication, we introduce a novel technique, based on the Kirkendall effect, to fabricate Ti-Al micrometer/nanometersized porous alloys with adjustable pore sizes ranging from several tens of micrometer to several tens of nanometers. In the late 1930s, Kirkendall et al. [5] discovered that the interface between copper and zinc in brass moved at an elevated temperature due to their different diffusion rates. This phenomenon was later referred to as the Kirkendall effect. It has been well documented that the Kirkendall effect leads to pore formation in materials. [6][7][8] In general, these pores impact negatively on the mechanical properties, so that significant efforts have been devoted to remove these pores for engineering applications. [9] However, in recent years, the Kirkendall effect has been used to fabricate special structures, such as hollow nanocrystals [7] and hierarchical porous iron oxide films. [8] In this regard, the Kirkendall effect can be used to produce porous alloys if there exists great diffusion-rate discrepancies between components in the alloy system. Two procedures for fabricating porous Ti-Al alloys via the Kirkendall effect are illustrated in Figure 1a. In the first procedure, commercial Ti and Al elemental powders were mixed and cold pressed into both disc and tubular compacts, followed by the solid sintering process (in which the Kirkendall effect occurs). Considerable expansion of these compacts has been observed and their examples are shown in Figure 1b and c. The final shape of a compact with the porous structure is important for practical applications. Through the precise control of the sintering process and the avoidance of the formation of the liquid phase, we have managed to preserve the sintered compacts in their original shapes (as shown in Fig. 1b and c) even though a great volume expansion occurred. Under an identical sintering condition (initially sintered at 600°C for 60 min and then sintered at 1300°C for 30 min), the porous materials of three structures of Ti-Al alloys (i.e., a 2 -Ti 3 Al, c-TiAl, and TiAl 3 ) could be fabricated when different ratios of Al and Ti powders were mixed. A typical example of the alloy with the nominal...

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Here, we report a form of nanostructures bicrystal nanoribbons. Zinc sulfide (ZnS) bicrystal nanoribbons were prepared via simple thermal evaporation of a powder mixture of ZnS and SiO. The product was characterized with transmission electron microscopy (TEM), high-resolution TEM, and electron energy loss spectroscopy. The ZnS bicrystal nanoribbons have widths of 50–500 nm and lengths of several tens of micrometers. Two kinds of growth direction, i.e. [−1−21] and [−1−31], have been found. The growth of the ZnS bicrystal nanoribbons was considered to involve a combination of oxide-assisted and vapor-liquid-solid processes.

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