Phosphide Alloys Research Articles

Porous Nickel-Molybdenum Phosphide Alloy Electrodes for Alkaline Hydrogen Evolution Reaction at the High-Current Density

Porous Nickel-Molybdenum Phosphide Alloy Electrodes for Alkaline Hydrogen Evolution Reaction at the High-Current Density

Preparation and performance of Ti/Ti-DLC composite coatings for precision glass molding

Precision glass molding (PGM) is an efficient process used for batch manufacturing of high-precision glass optical elements. In this process, nickel phosphide (Ni–P) alloy is commonly utilized as a mold material due to its superior turning properties. However, the Ni–P mold suffers from issues such as diffusion of phosphorus elements, poor wear resistance, and easy peeling of the DLC coating during molding. To address these problems, the current study proposes enhancing the molding performance of mold by depositing a composite coating layer of Ti/Ti-DLC onto the surface of Ni–P using the filtered cathodic vacuum arc technology (FCVA). The effects of different flow rates of C2H2 on Ti-DLC coatings were analyzed in terms of composition, microstructure, mechanical, tribological, and molding properties. The results revealed that as the C2H2 flow rate increased, the Ti content of coatings decreased from 13.56 to 2.17 at.%. Additionally, the film microstructure transformed from TiC polycrystalline composite films to nanocrystalline amorphous composite films and finally to amorphous films. The Ti-DLC coatings with a nanocrystalline composite structure exhibited excellent overall performance when Ti content is 7.75 at.%. These coatings are suitable as protective coatings for microstructured array mold and demonstrate good stability at a molding temperature of 500 °C.

Ni–Fe–P/Fe–Si electrocatalysts on iron sheets: Regulating surface structure to amorphous heterojunction for excellent oxygen evolution reaction

Nickel iron bimetallic phosphide alloys are a promising electrocatalyst for oxygen evolution reaction (OER). In this work, a highly active Ni–Fe–P/Fe–Si heterojunction electrocatalyst for OER has been synthesized by one-step electrodeposition on iron plate. The synergism effect of Ni–Fe–P alloy and Fe–Si alloy particles after dealloying treatment promotes the construction of nanoflower-like heterogeneous structure with rich lattice defects and exposes a highly open multi-stage nanostructure surface. Furthermore, Si induced the localized electron redistribution optimizes catalytic performance by accelerating electron transfer. The optimal Ni–Fe–P/Fe–Si OER catalyst requires a much low overpotential of 209 mV at a current density of 10 mA cm−2, and 270 mV at a current density of 200 mA cm−2. The prepared Ni–Fe–P/Fe–Si electrode can maintain a current density of 10 mA cm−2 within 24 h, which shows significant electrochemical stability. This study provides a new prospect for the preparation of cost-effective heterogeneous catalysts.

First-Principles Investigation of Concentration Effects on the Electronic and Vibrational Properties of a Boron Aluminum Phosphide Alloy with Wurtzoid Nanostructure

The vibrational and electronic properties of the binary wurtzoids Al7P7 and B7P7 and the ternary one BxAl7-xP7 have been investigated by the use of the approximation of the Density Functional Theory (DFT). By varying the concentration x, we carried out the calculations and various simulations of the bond lengths, energy gap, density of states, force constants, reduced masses, and infrared and Raman spectra. The geometric nanostructure of BxAl7-xP7 wurtzoid has been analyzed using the Gauss view 05 program. As the concentration of B increases, the energy gap widens, indicating that the estimations are consistent with the experimental longitudinal optical measurements. We utilize the theoretical ab initio technique to mimic the properties and nanostructures of BxAl7-xP7 wurtzoid using DFT B3LYP with the 6-311-G** basis sets and the GGA calculations with all electrons.

NiyCo2-yP alloy catalysts with assistance of Y for boosting Low-pressure hydrogenation transformation of Biomass-derived levulinic acid or furfural in water

Acquiring practical catalysts was crucial for promoting the application of advanced chemical transformations. Here, a series of Co-Ni-P catalysts with addition of Y were designed for hydrogenation transformation of biomass-derived levulinic acid (LA) or furfural (FAL) in water. The molar-composition-manipulated catalysts were characterized in Co-Ni phosphide alloy nanostructure with YPO4 enriched on surface and denoted as (YPO4)x/CoyNi2-yP. By comprehensive catalytic measurements, both Co:Ni ratio in phosphide alloy and amount of YPO4 were testified to be key factors to modulate intrinsic catalytic properties (hydrogen activation and acid catalysis) along Y-Co-Ni-P interface, the attractive and reproducible yield for desired product γ-valerolactone (up to 98 %) or cyclopentanone (up to 93%) could achieve under low H2 pressure of 0.1–0.5 MPa over the well modulated catalyst (YPO4)0.2/Co1.0Ni1.0P in comparison with high H2 pressure (beyond 1.0 MPa) required in most of literature systems, indicating that the efficiency and feasibility of these important biomass transformations could be greatly enhanced on the low-cost and robust (YPO4)x/CoyNi2-yP catalysts. These findings suggested that the phosphide-alloy engineering technique provided in this work could serve as a novel and practical method for innovating competitive catalysts to boost advanced heterogeneous catalysis applications as well as current aqueous hydrogenation transformations of biomass derivatives.

Ruthenium-manganese phosphide nanohybrid supported on graphene for efficient hydrogen evolution reaction in acid and alkaline conditions

Transition metal phosphides (TMPs) have been proved to be promising, economical and effective catalysts for hydrogen evolution reaction (HER). Precious metals with transition metals alloying can appropriately adjust the adsorption energy, which is an effective solution for greatly reducing the cost of noble metal catalysts and improving their inherent performance. Herein, a simple method was employed to synthesize MnRuPOGO-500 nano-catalysts with a particle size of about 5 nm, which showed excellent HER performance under both acid and basic media. In acidic solution, the optimal catalyst displayed the overpotential of HER to reach 10 mA cm−2 with 109 mV, a small Tafel slope of 38.55 mV dec−1 and long-time durability of 60 h. Especially in alkaline medium, the low overvoltage of 27 mV, a small Tafel slope of 57.35 mV dec−1 and continuing stability of 48 h were further achieved. Meanwhile, we can find that manganese has negligible HER activity, but the doping of manganese generates a synergistic modulation effect in the MnP–Ru2P alloy, thereby improving the HER performance of the catalyst. This paper brings a simple scheme and unique insights to the design of transition metals and platinum group metals (PGMs) phosphide alloy electrocatalysts.

Exploring the stable structures and photovoltaic properties of an ideal pseudo-binary alloy: Indium gallium phosphide

Pseudo-binary III-V semiconductor alloys are promising for applications in optical, photovoltaic and photoelectrochemical fields, for their tunable band gaps and band alignments. In this work, we carefully investigate structural and photovoltaic properties of indium gallium phosphide (InxGa1-xP; 0 < x < 1) alloys. Using evolutionary algorithm crystal structure prediction, we perform structure searches for indentifying potential crystal structures of InxGa1-xP alloys in nine chemical compositions at zero temperature and ambient pressure. We find that InxGa1-xP alloys can adopt zinc blende (ZB) and wurtzite (WT) structures and the former generally have lower energy than the latter at all compositions. Based on these predicted InxGa1-xP structures, we evaluated their spectroscopic limited maximum efficiencies (SLMEs) and find that InxGa1-xP alloys with high In concentrations (x ≥ 0.5) have higher SLME values than those of InxGa1-xP alloys with low In concentrations (x < 0.5). We also find that SLMEs of disordered InxGa1-xP alloys are larger than those of ordered alloys due to the enhanced oscillator strengths.

Effect of evaporation behavior of zinc tin phosphide alloys on the composition, structure, and photoconductive properties of their thin films

The evaporation behavior of zinc tin phosphide (ZTP) alloys and its effect on the composition, structure, and photoconductive properties of the deposited films were investigated. ZTP alloys were prepared, and they were found to be of ZnSn-phosphide composition and chalcopyrite structure as obtained by thermogravimetric and x-ray diffraction analysis. The evaporation of the alloys produced random and inhomogeneous deposition with unevaporated residues due to the large difference in vapor pressure, particularly, between Zn and Sn. A closed spaced vapor deposition type setup favored uniform deposition of the films, however, with a dramatic deviation of composition and structure from that of the alloys. Rutherford backscattering, x-ray photoelectron, and energy dispersive spectroscopic studies revealed that the composition of the films is close to ZnP2 stoichiometry with less than 2% of Sn content. Raman spectroscopy and transmission electron microscopy studies showed that the films are of polycrystalline tetragonal ZnP2 structure and evolve to monocrystalline on electron irradiation. The films exhibited a broad band photoresponse in the visible wavelength region with high responsivity to the red light. The study establishes the effect of evaporation behavior of materials with large difference in vapor pressure on the properties and activity of the deposited films thereof.

High-Performance Transition Metal Phosphide Alloy Catalyst for Oxygen Evolution Reaction.

Oxygen evolution reaction (OER) is a pivotal process in many energy conversion and storage techniques, such as water splitting, regenerative fuel cells, and rechargeable metal-air batteries. The synthesis of stable, efficient, non-noble metal-based electrocatalysts for OER has been a long-standing challenge. In this work, a facile and scalable method to synthesize hollow and conductive iron-cobalt phosphide (Fe-Co-P) alloy nanostructures using an Fe-Co metal organic complex as a precursor is described. The Fe-Co-P alloy exhibits excellent OER activity with a specific current density of 10 mA/cm2 being achieved at an overpotential as low as 252 mV. The current density at 1.5 V (vs reversible hydrogen electrode) of the Fe-Co-P catalyst is 30.7 mA/cm2, which is more than 3 orders of magnitude greater than that obtained with state-of-the-art Fe-Co oxide catalysts. Our mechanistic experiments and theoretical analysis suggest that the electrochemical-induced high-valent iron stabilizes the cobalt in a low-valent state, leading to the simultaneous enhancement of activity and stability of the OER catalyst.

Few-Layer Black Phosphorus Carbide Field-Effect Transistor via Carbon Doping.

Black phosphorus carbide (b-PC) is a new family of layered semiconducting material that has recently been predicted to have the lightest electrons and holes among all known 2D semiconductors, yielding a p-type mobility (≈105 cm2 V-1 s-1 ) at room temperature that is approximately five times larger than the maximum value in black phosphorus. Here, a high-performance composite few-layer b-PC field-effect transistor fabricated via a novel carbon doping technique which achieved a high hole mobility of 1995 cm2 V-1 s-1 at room temperature is reported. The absorption spectrum of this material covers an electromagnetic spectrum in the infrared regime not served by black phosphorus and is useful for range finding applications as the earth atmosphere has good transparency in this spectral range. Additionally, a low contact resistance of 289 Ω µm is achieved using a nickel phosphide alloy contact with an edge contacted interface via sputtering and thermal treatment.

Construction of high electrical conductive nickel phosphide alloys with controllable crystalline phase for advanced energy storage

Nickel–based compounds are promising energy storage materials due to their high specific capacitance and energy density, but their practical applications are severely prevented by the poor rate capability which ascribed to the low conductivity. Herein controllable synthesis of high electrical conductive nickel phosphide alloys is achieved by conversion of Ni3C into Ni2P, Ni7P3 and Ni12P5 using trioctylphosphine as phosphorus source. The current-voltage curves indicating that the conductivity of these nickel phosphide alloys is higher than commercial graphite. They deliver excellent electrochemical characteristics including high specific capacitance and excellent rate capability. Simultaneously, the asymmetric supercapacitors with high energy density and long cycle life are also assembled based on nickel phosphide alloys as positive electrode and activated carbon as negative electrode. The AC//Ni2P asymmetric supercapacitor delivers the highest specific capacity of 239.5Cg−1 at a current density of 0.5Ag−1 and a maximum energy density of 53.2Whkg−1 (at a power density of 0.3998kWkg−1). The study will provide a new strategy for the construction of high performance energy storage materials by enhancing their intrinsic electrical conductivity and controlling their microstructure.

Liquid Phase Synthesis of CoP Nanoparticles with High Electrical Conductivity for Advanced Energy Storage

Transition metal phosphide alloys possess the metalloid characteristics and superior electrical conductivity and are a kind of high electrical conductive pseudocapacitive materials. Herein, high electrical conductive cobalt phosphide alloys are fabricated through a liquid phase process and a nanoparticles structure with high surface area is obtained. The highest specific capacitance of 286 F g−1 is reached at a current density of 0.5 A g−1. 63.4% of the specific capacitance is retained when the current density increased 16 times and 98.5% of the specific capacitance is maintained after 5000 cycles. The AC//CoP asymmetric supercapacitor also shows a high energy density (21.3 Wh kg−1) and excellent stability (97.8% of the specific capacitance is retained after 5000 cycles). The study provides a new strategy for the construction of high-performance energy storage materials by enhancing their intrinsic electrical conductivity.

New III-V Semiconductor Alloys for Solar Hydrogen Production

Dilute III-V alloys have garnered immense interest as suitable materials for solar hydrogen generation due to their compositional tunable band gaps, high carrier mobilities and high absorption coefficients. Till date there are no III-V materials that can satisfy all the stringent criteria for photoelectrochemical water splitting. In this presentation, we report two new III-V materials GaSbN and GaSbP that addresses current materials bottleneck for photoelectrochemical water splitting is developed for photoelectrochemical water splitting. Applicability of the Ga(Sb x )N1−x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory and experiments. Theoretical results predict that Ga(Sb x )N1−x , GaSbP alloys with 2 eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sb x )N1−x alloys could be potential candidates for splitting water under visible light irradiation.1,2 Theoretical computations with Sb composition beyond 7% change the electronic band gap from direct to indirect. In the case of GaSbP a small amount of Sb incorporation will change the indirect GaP band gap to direct band gap.3 Experimental synthesis is carried out using metal organic chemical vapor deposition using trimethyl gallium (TMGa) and Trimethyl Antimony (TMSb) and ammonia. Crystalline GaSbxN1-x films were obtained at x values ranging from 0-5%. The synthesis was carried out on different planar substrates and GaN nanowires. Optical measurements confirm that severe band gap reduction occurs with incorporation of antimony in to GaN as predicted by the theoretical calculations. X-Ray Diffraction (XRD) results confirm the lattice expansion at small concentrations of antimony. This work is the first successful attempt on the experimental synthesis of crystalline GaN and GaP based alloy in the low antimonide regime and photoelectrochemical data on activity, band edge energetics and stability show high suitability for direct solar water splitting. The fundamental insights gained from this work on the growth mechanisms and formation of stacking faults can be extended to other ternary alloy nanowires of interest. From a scientific point of view, the large band gap bowing and corresponding optical properties with very small alloying compositions is interesting and can be exploited for band gap engineering. This presentation will highlight our results with both synthesis and photoelectrochemical characterization of GaSbN and GaSbP alloys. Acknowledgements: Financial support from US Department of Energy (DE-FG02-07ER46375) and NSF (DMS1125909). R.M. Sheetz, E. Richter, A.N. Andriotis, C. Pendyala, M.K. Sunkara and M. Menon, “Visible light absorption and large band gap bowing in dilute alloys of gallium nitride with antimony”, Phys. Rev. B, 84, 075304 (2011)S. Sunkara, V.K. Vendra, J.B. Jasinski, T. Deutsch, A.N. Andriotis, K. Rajan and M.K. Sunkara, “New Visible Light Absorbing Materials for Solar Fuels, Ga(Sbx)N1-x”, Adv. Mater., 26 (18), 2878-2882 (2014). H.B. Russell, A.N. Andriotis, M.Menon, J. Jasinski and M.K. Sunkara, “Direct Band Gap Gallium Antimony Phosphide (GaSbxP1-x) Alloys”, Submitted (2015).

A theoretical investigation of the band alignment of type-I direct band gap dilute nitride phosphide alloy of GaNxAsyP1–x–y/GaP quantum wells on GaP substrates

The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integration of laser diodes on Si microprocessors. The major advantage of this newly proposed laser material system is the small lattice mismatch between GaP and Si. However, the large threshold current density of these promising laser diodes on Si substrates shows that the carrier leakage plays an important role in Ga(NAsP)/GaP QW lasers. Therefore, it is necessary to investigate the band alignment in this laser material system. In this paper, we present a theoretical investigation to optimize the band alignment of type-I direct band gap GaNxAsyP1–x–y/GaP QWs on GaP substrates. We examine the effect of nitrogen (N) concentration on the band offset ratios and band offset energies. We also provide a comparison of the band alignment of type-I direct band gap GaNxAsyP1–x–y/GaP QWs with that of the GaNxAsyP1–x–y/AlzGa1–zP QWs on GaP substrates. Our theoretical calculations indicate that the incorporations of N into the well and Al into the barrier improve the band alignment compared to that of the GaAsP/GaP QW laser heterostructures.

Band structure parameters of quaternary phosphide semiconductoralloys investigated by magneto-optical spectroscopy

The spin-flip Raman scattering by the epitaxial layers ofquaternary aluminium gallium indium phosphide alloys lattice matched togallium arsenide has been investigated in order to gain insight into theband structure parameters of this material system. Both electron and holespin-flip Raman signals were observed and were identified by theirbehaviour on the application of a biaxial strain to the epilayer. Thegyromagnetic ratios of the electron and hole were determined and it wasfound that a three-band k·p model gives a gooddescription of the experimental values of the conduction band gyromagneticratio as a function of composition; these data provide a new insight intothe dependence of the spin-orbit splitting on composition.

Microcalorimetric Studies of CO and H2 Adsorption on Nickel, Nickel−Boride, and Nickel−Phosphide Catalysts

Nickel powder, and nickel boride (Ni-B) and nickel phosphide (Ni-P) alloy particles prepared by aqueous chemical reduction, were studied by microcalorimetry. Treatment of Ni powder, Ni-B, and Ni-P in H2 at 623 K was sufficient to produce reduced nickel surfaces for chemisorption. After treatment, these samples were shown by X-ray diffraction to be crystalline. The presence of B and P increased the BET surface areas to values of 8.4 and 19.7 m2/g, respectively, compared to the value of 1.7 m2/g for Ni powder. Microcalorimetric measurements of CO and H2 adsorption performed at 308 K on reduced Ni powder exhibited initial heats of 120 and 85 kJ/mol, respectively. The presence of B decreased the initial heats of CO and H2 adsorption by 20 and 10 kJ/mol, respectively and decreased the saturation uptakes of these molecules per unit surface area. The presence of P decreased the initial heats of CO and H2 adsorption by 30 and 20 kJ/mol, respectively, and also decreased the saturation uptakes of these molecules per unit surface area.

Siamese cell for group V flux measurements, uniform arsenide phosphide alloys, and quaternary lasers

We have used an effusion cell with independently valved solid arsenic and red phosphorus sources and a common cracking zone to prepare extremely uniform composition GaAs(1−x)Px epitaxial films on 3 in. diam substrates. Mass spectrometry and ion gauge measurements of dimer species allowed determination of ionization sensitivities for phosphorus and arsenic species in good agreement with the relationship of Flaim and Ownby [J. Vac. Sci. Technol. 8, 661 (1971)]. From the mass spectrometer data, it was possible to determine the thermodynamic equilibrium constant 1.9+/−0.4, and hence free energy −0.55 eV molecule−1 for the process As2+P2■2 AsP. Finally double heterojunction GaInAsP/InP lasers grown with this cell and operating at room temperature have transparency threshold currents below 800 A cm−2.

The role of oxygen in increasing the carrier concentration of n-type silicon germanium-gallium phosphide alloys

The role of oxygen in increasing the carrier concentration of n-type silicon germanium-gallium phosphide alloys was investigated. It was found that silicon germanium-gallium phosphide alloy without additional dopant prepared by mechanical alloying and cold pressing is p-type if heat treated in argon or hydrogen, but is n-type if heat treated in air. The results indicate that carrier enhancement probably relates to the dissociation of gallium phosphide followed by oxidation of the dissociated gallium and phosphorus. A possible mechanism for carrier enhancement in n-type silicon germanium-gallium phosphide alloys is proposed.

The effect of high-temperature heat treatment on the electrical power factor and morphology of silicon germanium-gallium phosphide alloys

The results of an experimental investigation into the effect of high-temperature heat treatment on the electrical resistivity and Seebeck coefficient of silicon germanium-gallium phosphide alloys and the accompanying changes in morphology are reported. The specimens were heat treated for different periods of time and quenched or allowed to cool slowly in air. Their morphology was investigated using scanning electron microscopy and electron spectroscopy for chemical analysis. The electrical resistivity and Seebeck coefficient were measured as a function of temperature from room temperature to about 800 K. Substantial changes in the electrical properties and in morphology were observed after 15 min and 4-h periods of heat treatment, respectively. A less significant decrease in electrical resistivity accompanied further heat treatment. However, the Seebeck coefficient remained almost constant which resulted in an increase in the electrical power factor. Prior to heat treatment, the alloy consisted of host matrix and a silicon-rich black phase. Heat treatment was accompanied by the appearance of a white phase which was rich in germanium and gallium phosphide. Although in general it was not possible to correlate the changes in electrical properties with the morphology. The highest power factor obtained in this investigation corresponded to a morphology which consisted of the host matrix and a significant proportion of white phase.

Amorphous Nickel Phosphide Alloy Coatings Obtained by Magnetron Sputtering Methods for Magnetic Recording Disk

Ni‐P thin films were deposited from a target under various deposition conditions using the magnetron sputtering technique. The effects of deposition parameters on crystallization behavior and physical properties of the films were investigated. It has been observed that the first crystallization temperature increases as the pressure and deposition rate decrease. The electrical resistivity of the films also shows a marked dependence on deposition conditions. The resistivity of the films varies with deposition rate and exhibits a minimum at a rate of about 5 Å/s.