Ternary Transition Metal Phosphides Research Articles

Hierarchical Design of Homologous NiCoP/NF from Layered Double Hydroxides as a Long-Term Stable Electrocatalyst for Hydrogen Evolution

Ternary transition metal phosphides (TTMPs) with two-dimensional heterointerface and adjustable electronic structures have been widely studied in hydrogen evolution reactions (HER). However, single-phase TMPs often have inappropriate H* adsorption energy and electronic transfer efficiency in HER. Herein, we utilized the heterogeneity in the crystal structure to design an efficient and stable catalyst from the NiCoP nanowire@NiCoP nanosheet on nickel foam (NW-NiCoP@NS-NiCoP/NF) for HER. Layered double hydroxides (LDHs) with a heterogeneous matrix on crystal surfaces were grown under different reaction conditions, and non-metallic P was introduced by anion exchange to adjust the electronic structure of the transition metals. The hierarchical structure of homologous NiCoP/NF from the LDH allows for a larger surface area, which results in more active sites and improved gas diffusion. The optimized NW-NiCoP@NS-NiCoP/NF electrode exhibits excellent HER activity, with an overpotential of 144 mV, a Tafel slope of 84.2 mV dec−1 at a current density of 100 mA cm−2 and remarkable stability for more than 500 h in 1.0 M KOH electrolyte. This work provides ideas for elucidating the rational design of structural heterogeneity as an efficient electrocatalyst and the in situ construction of hierarchical structures.

Morphology and Composition Regulation of FeCoNi Prussian Blue Analogues to Advance in the Catalytic Performances of the Derivative Ternary Transition‐Metal Phosphides for OER

AbstractPrussian blue analogues (PBAs) are mostly binary metallic compounds with a cubic structure, which greatly limits the structure and component of derived transition‐metal phosphides (TMPs) and affects their catalytic activities. This work focuses on regulating the morphology and composition of the PBA at the front‐end to optimize the OER performance of the derived TMP. By temperature control surfactant desorption ability, we obtain a series of ternary FeCoNi (FCN‐PBAs). With the increase of temperature, their morphologies change from truncated octahedrons to cubic octahedrons and truncated cubes, in which the Fe content basically remains unchanged and the Co/Ni ratio gradually decreased. Due to the synergistic effect among ternary TMPs, all phosphidation products (FCN‐P) exhibit better OER activities than RuO2, among which FCN‐40‐P shows the best performance. As confirmed by XPS analyses, the appropriate chemical composition enhances the oxidizabilityof TM species, promotes the chemical adsorption of OH−, and accelerates OER kinetics.

Binary and ternary transition metal phosphides for dry reforming of methane

Mo-based phosphides showed higher activity for CH4–CO2 reforming than Fe2P, WP, CoP and Ni2P.

Core–Shell FeCo Prussian Blue Analogue/Ni(OH)2 Derived Porous Ternary Transition Metal Phosphides Connected by Graphene for Effectively Electrocatalytic Water Splitting

As a promising new-star electrocatalyst, transition metal phosphide (TMP) has been widely applied in electrocatalytic hydrogen and oxygen evolution reactions (HER and OER). However, the current cat...

Binary and Ternary Earth-Abundant Transition Metal Phosphides As Electrocatalysts and Photocatalysts for Water Splitting

To provide a sustainable carbon free energy system while moving away from fossil fuels and greenhouse gas (CO2) generating energy sources, an inexpensive and reliable process to produce hydrogen has to be implemented. Water splitting by electrolysis has been thought of as the ideal way to produce hydrogen but the current electrolysis of water requires energy or rare materials that make the process neither carbon independent or feasible due to the amount energy gained vs energy input. In this talk there are two methods to perform the electrolysis of water: a) electrocatalytic water-splitting and b) solar photo-electrochemical water-splitting. Recently, transition metal phosphides (TMP) have shown promising catalytic properties for the water splitting half reactions. Two key aspects to studying TMPs for the electrolysis of water are 1) to generate hydrogen with as little energy input as possible; meaning using materials that can harness solar energy or that have significantly low overpotentials for each water splitting half reactions and 2) to find competitive materials to rival the performance and stability of platinum and other noble metals so that industrial production and manufacturing may be achieved. This talk will focus on binary and ternary transition metal phosphides as electocatalysts and photocatalysts for the hydrogen and oxygen evolution reactions; transition metals of focus primarily include Nickel, Molybdenum, and Cobalt with Platinum and Titanium as reference metals. Phosphorus (P) atoms have been determined to stabilize the TMP surface structure and thus the concentration of surface P is a key factor in controlling the surface activity. To control size, shape and crystallinity, a colloidal synthesis method was used to synthesize the nano particles. MoxCo2-xP and Ni2-xMoxP ternary TMPs were synthesized owing to their synergistic effects towards electrocatalysis. These two specific ternary phosphides are being considered for the proposed work influenced by commercial hydrotreating ternary catalyst system (sulfided Co-Mo and Ni-Mo). Nickel phosphide is of primary interest resulting from its consistent performance over other TMPs as an electrocatalyst for water splitting. As electrocatalysts, TMPs show low overpotentials and good stability for the hydrogen-evolution reaction (HER) and oxygen-evolution reaction (OER) under relevant current densities (10 mA/cm2) without any sacrificial agent present. The particles show high stability under most conditions, specifically in acidic electrolytes. In our group, work has been done to synthesize, characterize and test TMP nanoparticles as electrocatalysts and photocatalysts using PEC methods for the HER and OER to understand the material’s electrochemical behavior. Electrode preparation methods may influence the behavior, stability and reproducibility of the electrode. Therefore, multiple preparation methods were conducted to determine the true performance of the material. FTO on glass and Titanium foil were used as substrates/current collectors for the catalytic nano-particles. The electrocatalytic performance of the binary and ternary TMPs have been evaluated as well as the photocatalytic performance. The photocatalytic testing was evaluated under 1 SUN (100mW/cm2) illumination from a 150 W Xe Lamp with and without an AM1.5 filter. The photocatalytic performance was evaluated for the materials tuned to have more semiconductor characteristics and that show signs of photovoltage. Various ratios of metal to phosphide and metal to metal alloys were examined to study the effect of the electrocatalytic and photocatalytic performance and the material’s stability.

Thin Films of (Fe1–xCox)3P and Fe3(P1–xTex) from the Co-Decomposition of Organometallic Precursors by MOCVD

A new method for preparing thin films of ternary transition metal phosphides has been developed. The ferromagnetic compound Fe3P has been doped with cobalt and tellurium by decomposing H2Fe3(CO)9PtBu with either Co3(CO)9PtBu or H2Fe3(CO)9Te via metal–organic chemical vapor deposition (MOCVD) onto a quartz substrate. Solid mixtures of the organometallic clusters were vaporized and decomposed at 400 °C to produce films that were subsequently annealed under vacuum at 650 °C for 24 h to afford crystalline films of (Fe1–xCox)3P (0.09 < x < 0.22) and Fe3(P1–xTex) (0.04 < x < 0.42). The films exhibit phase purity as confirmed by powder X-ray diffraction and X-ray photoelectron spectroscopy, which also confirmed the homogeneity of the films. Changes in elemental ratios were tracked by unit cell constants and ICP-OES analysis. Field-dependent magnetization measurements showed magnetic hysteresis with similar magnetic saturation values for each doped material. Thermogravimetric analysis was used to compare the Curi...

Electrochemical Behaviors of Binary and Ternary Manganese Phosphides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Electrochemical Behaviors of Binary and Ternary Manganese Phosphides

The present work provides a comparative study of the electrochemical behaviors of binary and ternary manganese phosphides toward lithium. The redox mechanism involved in these two electrodes is elucidated by means of galvanostatic and in situ X-ray diffraction measurements and first-principles calculations. Compared to the previous study reported on MnP4, two additional processes are here clearly identified: after a first conversion process that transforms the binary MnP4 electrode into Li7MnP4, a partial and irreversible decomposition of Li7MnP4 into Li3P + Mn0 is achieved, responsible for the poor electrodes capacity retention. In charge, the formation of an amorphous low-lithiated Li∼1 MnP4 phase, very similar to the charged LixVP4 and LixTiP4 electrodes ever reported, is shown to compete with the kinetically limited MnP4 reconstruction. This suggests that the high performances of ternary transition metal phosphides could be combined with the technological advantage of using more suitable nonlithiated ...

Binary and Ternary Transition-Metal Phosphides as HDN Catalysts

Transition-metal phosphides (Co2P, Ni2P, MoP, WP, CoMoP, NiMoP) were prepared by reducing metal oxide/phosphate precursors in a flow of H2. The solids obtained were tested in the hydrodenitrogenation of o-propylaniline at 643 K and 3 MPa. All the catalysts were active, with product selectivities resembling those of sulfidic catalysts. The influence of H2S on the activity and selectivities was tested and is discussed with regard to a possible surface modification. Based on the surface area of each catalyst, we estimated the relative intrinsic activities of the different phosphides. According to this estimation, MoP was intrinsically the most active catalyst.

Structural chemistry of a new ternary zirconium cobalt phosphide, Zr 5Co 19P 12

Zr 5Co 19P 12 has a new structural type closely related to Hf 2Co 4P 3. It has hexagonal symmetry with the space group P 62m ( D 3 h 3) and the lattice constants a = 11.885(6) A ̊ , c = 3.596(3) A ̊ , c a = 3.304(9) , v = 439.32 A ̊ , with one formula unit per cell. This structure is connected to those of binary and ternary transition metal phosphides and can usefully be described in the same way on the basis of the phosphorus lattice.

Superconductivity and crystal structure of a new class of ternary transition metal phosphides TT/t'P (TZr, Nb, Ta and T/t'Ru, Rh)

A new series of superconducting ternary transition metal phosphides TT/t'P (TZr, Nb, Ta and T/t'Ru, Rh) was synthesized. A single-crystal structural determination for ZrRuP yielded an orthorhombic structure (space group, Pnam) with a final R value of 0.036. The superconducting transition temperature is strongly dependent on the electronic structure with TaRhP possessing the highest T c of 4.7 K. The compound ZrRuP crystallizes in two modifications: the hexagonal phase has a T c of 13.0 K and the orthorhombic structure has a T c of 3.5 K. The relationship between the crystal chemistry and superconducting properties for these two modifications is discussed.

Ternary transition metal phosphides: High-temperature superconductors

Two systems of ternary transition metal phosphides with the ordered Fe(2)P-type hexagonal structure are reported. They have the general formula MRuP and MOsP, in which M can be Ti, Zr, or Hf. An onset of the superconducting transition temperature as high as 13.0 K is reported for the ZrRuP compound.

Mössbauer study of phosphides containing iron

A series of binary and ternary transition metal phosphides containing iron has been investigated by Mössbauer spectroscopy. Most of the compounds studied show complex magnetic behaviour, and interpretations are proposed for some cases. The crystallographic ordering mechanism in Me 2P-type phosphides is discussed, and it is shown that great care must be taken in assigning the observed components of the Mössbauer spectra to the various crystallographic positions of the iron atoms.