A feasible approach to the synthesis of nickel phosphide for hydrodesulfurization

Applications, performance enhancement strategies and prospects of NixPy in electrocatalysis

Developing low-cost and high-efficiency electrocatalysts is the key to making energy-related electrocatalytic technologies commercially feasible. In recent years, nickel phosphide (NixPy) electrocatalysts have received extensive attention due to their multiple active sites, adjustable structure and composition, and unique physicochemical properties. In this review, the latest progress of NixPy in the field of electrocatalysis is reviewed from the aspects of the properties of NixPy, different synthesis methods, and ingenious modulation strategies. The significant enhancement effects of elemental doping, vacancy defect, interfacial engineering, synergistic effect, and the external magnetic field excitation-enhanced strategy on the electrocatalytic performance of NixPy are emphasized, Moreover, a forward-looking outlook for its future development direction is provided. Finally, some basic problems and research directions of NixPy in high-efficiency energy electrocatalysis are presented.

An adsorbate biased dynamic 3D porous framework for inverse CO2 sieving over C2H2

Separating carbon dioxide (CO2) from acetylene (C2H2) is one of the most critical and complex industrial separations due to similarities in physicochemical properties and molecular dimensions. Herein, we report a novel Ni-based three-dimensional framework {[Ni4(μ3-OH)2(μ2-OH2)2(1,4-ndc)3](3H2O)}n (1,4-ndc = 1,4-naphthalenedicarboxylate) with a one-dimensional pore channel (3.05 × 3.57 Å2), that perfectly matches with the molecular size of CO2 and C2H2. The dehydrated framework shows structural transformation, decorated with an unsaturated Ni(ii) centre and pendant oxygen atoms. The dynamic nature of the framework is evident by displaying a multistep gate opening type CO2 adsorption at 195, 273, and 298 K, but not for C2H2. The real time breakthrough gas separation experiments reveal a rarely attempted inverse CO2 selectivity over C2H2, attributed to open metal sites with a perfect pore aperture. This is supported by crystallographic analysis, in situ spectroscopic inspection, and selectivity approximations. In situ DRIFTS measurements and DFT-based theoretical calculations confirm CO2 binding sites are coordinatively unsaturated Ni(ii) and carboxylate oxygen atoms, and highlight the influence of multiple adsorption sites.

Synthesis and Composition Study of Electrochemically Deposited Ni-P Coating with Increased Surface Area

Nickel phosphides NixPy are a promising family of binary compounds that have shown much promise in various fields of technology, including energy storage, light absorption and heterogeneous catalysis in the reactions of biomass hydrogenation. The performance of NixPy-containing materials depends greatly on their morphology and phase composition and, in turn, on the synthesis technique. In this work, we have employed the electroplating approach to synthesize a Ni-P coating, which was treated with nitric acid in order to develop its surface area and enrich it with phosphorus. We have employed scanning electron microscopy, X-ray diffraction and 31P nuclear magnetic resonance techniques to characterize the particles separated from the coating with ultrasound for the convenience of the study. According to experimental data, the obtained powder contained a mixture of Ni3P and phosphorus oxides, which transformed into nickel phosphide phases richer with phosphorus, such as Ni5P2 and Ni12P5, after treatment at elevated temperatures. Thus, we have demonstrated that electroplating followed by acid treatment is a feasible approach for the synthesis of Ni-P coatings with increased surface area and variable phase composition.

Bifunctional and Self-Supported NiFeP-Layer-Coated NiP Rods for Electrochemical Water Splitting in Alkaline Solution

Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electrolysis, which is mainly limited by the oxygen evolution reaction (OER), for hydrogen production remains a major challenge for the hydrogen economy. In this work, a bimetallic NiFeP catalyst is coated on nickel phosphide rods grown on nickel foam (NiFeP@NiP@NF). This self-supported and interfacially connected electrode structure is favorable for mass transfer and reducing electrical resistance during electrocatalysis. The preparation of NiFeP@NiP@NF is optimized in terms of (i) the coprecipitation time of the NiFe Prussian blue analogue layer that serves as phosphides precursor and (ii) the phosphidation temperature. The optimized sample exhibits excellent OER performance delivering current densities of 10 and 100 mA cm^-2 at low overpotentials of 227 and 252 mV in 1.0 M KOH, respectively, and maintaining 10 mA cm^-2 for more than 120 h without obvious degradation. Moreover, it can also be operated as a hydrogen evolution electrocatalyst, requiring an overpotential of 105 mV at 10 mA cm^-2 in the same medium. Thus, the as-prepared material was tentatively utilized as a bifunctional electrocatalyst in a symmetric electrolyzer, requiring a voltage bias of 1.57 V to afford 10 mA cm^-2 in 1.0 M KOH, while exhibiting outstanding stability.

Citric acid modified Ni3P as a catalyst for aqueous phase reforming and hydrogenolysis of glycerol to 1,2-PDO

The addition of citric acid reduced the Ni3P particle size, leading to high performance in glycerol hydrogenolysis without external H2.

Novel synthesis of a NiMoP phosphide catalyst via carbothermal reduction for dry reforming of methane

NiMoP-Glu with small particle size and an appropriate carbon content showed higher catalytic activity and stability than NiMoP-H2.

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.

A Facile Method to Synthesize Ni2P Catalysts and their Catalytic Performances in Hydrotreating Reactions

The bulk and supported Ni2P catalysts (Ni2P/γ-Al2O3 and Ni2P/MCM-41) were facile prepared by using nickel metal as nickel source via thermal treatment of hypophosphite in a separated reactor. The thermal decomposition behaviors of sodium hypophosphite were studied by online mass spectra. The effects of atmosphere, temperature, reaction time, and P/Ni atomic ratio on the as-prepared Ni2P catalysts were investigated. The Ni2P catalysts can also be obtained by using NiCl2 as nickel source but not for NiO. Since the nickel source is nickel metal and Ni2P catalysts were prepared in a separated reactor, the as-prepared Ni2P catalysts from Ni0 can be directly used without further purification, but the as-synthesized Ni2P catalyst from NiCl2 source should be further treated to remove the residues (such as Cl–) before use. As the active species for hydrodenitrogenation (HDN), Ni2P shows much higher activity than Ni0. For hydrodearomatization (HDA), Ni2P/MCM-41 shows much lower activity than Ni/MCM-41 but much better resistance to S-containing compounds in hydrogenation of naphthalene. The mechanism for synthesizing Ni2P catalysts with this facile method is proposed by online mass spectra.

Novel synthesis of a NiMoP phosphide catalyst in a CH4-CO2 gas mixture

NiMo bimetallic phosphide was synthesized from its corresponding oxidic precursor in a 1 : 1 CH₄ : CO₂ gas mixture for the first time. The in situ synthesized NiMoP phase in the feed for CH₄-CO₂ reforming can exhibit a higher activity compared to the one prepared in H₂.

Electronic Modulation of Palladium in Metal Phosphide Nanoparticles for Chemoselective Reduction of Halogenated Nitrobenzenes

Tuning the electronic property of a transition metal plays an important role in the selective catalysis. Herein, the control synthesis of (Pd_x Ni_y )-P nanoparticles is reported. The binding energy of Pd3d_5/2 as a function of x/y ratio is well tunable from 335.3 to 335.9 eV. The composition-induced electronic modulation was correlated with the selective catalysis of (Pd_x Ni_y )-P in the reduction of halogenated nitrobenzenes. The electro-deficiency of Pd helped to improve the selectivity. The amorphous (Pd₃₈ Ni₂₆ )P₃₆ /C performed an exceptional selectivity in comparison with other related (Pd-Ni)-P/C, Pd₃₈ Ni₂₆ /C, and Pd/C. Various halogenated nitrobenzenes (chlorides, bromides, and iodide) were tolerant and the corresponding halogenated anilines were obtained in high yields. This work provides some clues for the rational design of bimetallic phosphides with covalent interactions to boost the catalysis.

Intense Femtosecond Laser-Mediated Electrical Discharge Enables Preparation of Amorphous Nickel Phosphide Nanoparticles

Reported here is a high-efficiency preparation method of amorphous nickel phosphide (Ni-P) nanoparticles by intense femtosecond laser irradiation of nickel sulfate and sodium hypophosphite aqueous solution. The underlying mechanism of the laser-assisted preparation was discussed in terms of the breaking of chemical bond in reactants via highly intense electric field discharge generated by the intense femtosecond laser. The morphology and size of the nanoparticles can be tuned by varying the reaction parameters such as ion concentration, ion molar ratio, laser power, and irradiation time. X-ray diffraction and transmission electron microscopy results demonstrated that the nanoparticles were amorphous. Finally, the thermogravimetric-differential thermal analysis experiment verified that the as-synthesized noncrystalline Ni-P nanoparticles had an excellent catalytic capability toward thermal decomposition of ammonium perchlorate. This strategy of laser-mediated electrical discharge under such an extremely intense field may create new opportunities for the decomposition of molecules or chemical bonds that could further facilitate the recombination of new atoms or chemical groups, thus bringing about new possibilities for chemical reaction initiation and nanomaterial synthesis that may not be realized under normal conditions.

Electrochemical Na-Insertion/Extraction Property of Ni-Coated Black Phosphorus Prepared by an Electroless Deposition Method

Electrical conductivity is one of the properties required for an active material, and it is extremely essential to exert its potential. In the present study, the strategy of coating a metal at a single particle level by an electroless deposition method was applied to enhance the cycling performance of phosphorus-based negative electrodes for Na-ion batteries. The deposition morphology and composition of the Ni coating layer were characterized by field-emission scanning electron microscopy, scanning transmission electron microscopy, and X-ray diffraction. In the 5 wt % Ni coating, an amorphous Ni layer of several nanometers thickness was homogeneously formed on the phosphorus surface, whereas a shell layer having a 200 nm thickness was formed in the order of Ni₁₂P₅, NiP₂, NiP₃, and metallic Ni from the surface toward the center in the 30 wt % Ni coating. Electrochemical impedance spectroscopic measurements clarified that the good electron transport proceeded throughout the developed conduction pathway to promote the phase transition to trisodium phosphide (Na₃P), leading to a high reversible capacity for phosphorus; the as-prepared black phosphorus showed only a reversible capacity of 140 mA h g^-1 at the 60th cycle, whereas the 30 wt % Ni-coated composite delivered a relatively high capacity of 780 mA h g^(P)-1. In addition, the expansion ratio of the electrode after the 30th desodiation was the lowest among the three kinds of electrodes. By contrast, cracks and exfoliation of the active material layer from the current collector were confirmed in the as-prepared black phosphorus. These results demonstrate that the upgraded performance accomplished using the 30 wt % Ni-coated composite with the Ni/Ni-P layer is due to the synergetic effects of the electron conduction channel and a buffer matrix against a large volumetric change (∼400%) in phosphorus during the charge-discharge reactions.

Metal–organic framework derived carbon-confined Ni2P nanocrystals supported on graphene for an efficient oxygen evolution reaction

Metal–organic framework derived carbon-confined Ni₂P nanocrystals supported on graphene with high effective surface area, more exposed active sites, and enhanced charge transport were successfully designed.

Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides

This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.

Catalytic performance and deoxygenation path of methyl palmitate on Ni2P/SiO2 synthesized using the thermal decomposition of nickel hypophosphite

Catalytic performance and deoxygenation path of methyl palmitate on Ni₂P/SiO₂ catalysts were systematically studied in a continuous flow fixed-bed reactor.

Metal–organic framework-derived nickel phosphides as efficient electrocatalysts toward sustainable hydrogen generation from water splitting

Ni-based metal–organic framework (MOF)-derived Ni₂P nanoparticles exhibited high-performance for electrochemical HER, as manifested by a low overpotential and a large cathodic current density.

A novel synthetic route to transition metal phosphide nanoparticles

A novel synthetic route was developed to prepare nano-sized and well-dispersed phosphides of transition metals (Mo, Ni, and Co) from their corresponding oxide precursors.

One-step synthesis of nickel and cobalt phosphide nanomaterials via decomposition of hexamethylenetetramine-containing precursors

New hexamethylenetetramine (HMT)-containing precursors were used to prepare well dispersed Ni₂P and Co₂P nanoparticles.

Synthesis of bulk and supported nickel phosphide using microwave radiation for hydrodeoxygenation of methyl palmitate

Ni₂P and Ni₂P/SiO₂ can be synthesized from nickel hypophosphite precursors at 230 °C for 5 min using microwave radiation.

Novel synthesis of dispersed molybdenum and nickel phosphides from thermal carbonization of metal- and phosphorus-containing resins

New (Mo,Ni),P-containing resin precursors to dispersed MoP and Ni₂P nanoparticles.