Metal Phosphides Research Articles

Air-Stable and Highly Active Transition Metal Phosphide Catalysts for Reductive Molecular Transformations

This review introduces transition metal phosphide nanoparticle catalysts as highly efficient and reusable heterogeneous catalysts for various reductive molecular transformations. These transformations include the hydrogenation of nitriles to primary amines, reductive amination of carbonyl compounds, and biomass conversion, specifically, the aqueous hydrogenation reaction of mono- and disaccharides to sugar alcohols. Unlike traditional air-unstable non-precious metal catalysts, these are stable in air, eliminating the need for strict anaerobic conditions or pre-reduction. Moreover, when combined with supports, metal phosphides exhibit significantly enhanced activity, demonstrating high activity, selectivity, and durability in these hydrogenation reactions.

In‐suit synthesis of FeP/C/CNT composites with excellent performance in supercapacitors and lithium‐ion batteries

AbstractIron phosphide (FeP) is a promising electrochemical energy storage material due to easy to obtain and high theoretical capacity. However, the intrinsic poor conductivity and the large volume change during charging and discharging process, result in a sharp decline in capacity and short cycle life for FeP. In this work, the FeP/C/CNT nanocomposite was synthesized efficiently and conveniently by one‐step solid‐phase synthesis method. Amorphous carbon‐coated FeP particles are embedded in a three‐dimensional network structure composed of highly conductive carbon nanotubes, drastically enhancing the conductivity of FeP and reducing the volume expansion during charging and discharging. In the three‐electrode system, the FeP/C/CNT composites showed good electrochemical performance, with a specific capacity as high as 124.4 mAh g−1 at 1 A g−1. Meanwhile, the constructed Ni2P@C/CNT//FeP/C/CNT asymmetric supercapacitor delivered a high energy density (70.73 Wh kg−1), power density (7.9 kW kg−1) and a long cycle life (10000 cycles). In addition, as served as an anode material in the lithium ion battery, the FeP/C/CNT composite also displayed as high as 601.8 mAh g−1of specific capacity at 0.1 A g−1 and a good cycle stability, showing superior electrochemical performance. The above work provides a promising composite material for supercapacitors and lithium ion batteries. Moreover, the solid‐state preparation methods can provide a reference for the synthesis of transition metal phosphides.

Preparation of the Amorphous NiCoP Nanosheet Array on Carbon Cloth for High‐Performance Solid‐State Hybrid Supercapacitor

AbstractThe outstanding performance of amorphous transition metal phosphides (TMPs) has garnered significant attention in the field of energy storage devices. However, the current approaches for obtaining TMPs require a high phosphidation temperature of over 350 °C, which cause a rise in crystallinity and inferior supercapacitive performance, along with the insufficient utilization of phosphidation agents. In this work, we designed a specially‐made quartz reactor to address this challenge. Using the specially‐designed reactor, the amorphous NiCoP nanosheet array was successfully synthesized on carbon cloth at a relatively low phosphidation temperature of 280 °C. The resulting nanosheet array grown on carbon cloth exhibited a high specific capacity of 338.33 mAh g−1 at a current density of 1 A g−1, along with exceptional cycling stability, retaining 92.3 % of its initial capacity after 1000 cycles. An asymmetric solid‐state hybrid supercapacitor assembled using the prepared amorphous NiCoP@CC‐1 material exhibited a high energy density of 50.98 Wh kg−1 at a power density of 800 W kg−1 while maintaining 92.7 % of initial specific capacity after 5000 cycles. The proposed approach is anticipated to facilitate the use of amorphous TMP materials in the development of high‐performance solid‐state hybrid supercapacitors.

Research on Urea Oxidation Coupled with Electrolysis of Water to Produce Hydrogen Based on (NiFe)2P Catalyst

Hydrogen production at low potential was realized by urea oxidation coupled water electrolysis. Transition metal phosphides ((NiFe)2P) were prepared by regulating polyvinylpyrrolidone (PVP) addition during the materials preparation, and their electrocatalytic performance for urea oxidation coupled hydrogen production was investigated. It was found that the material prepared with the PVP addition of 300 mg shows the best catalytic activity. The potential required to reach 100 mA cm−2 in KOH+urea solution is only 1.433 V with an impedance value of 4.128 Ω, which is 103 mV lower than that in KOH solution. Hydrogen evolution in KOH solution required 414 mV to reach −100 mA cm−2 with an impedance value of 48.75 Ω, while the potential required to reach the same current density in KOH+urea solution is only 343 mA with an impedance value of 5.65 Ω. As a result, the energy barrier and electron transfer resistance of electrocatalytic reaction can be significantly reduced by urea oxidation, and it provides a strategy for large-scale application of water electrolysis.

Iron phosphide nanoparticles anchored on N-doped carbon as efficient electrocatalysts for nitrate reduction reaction

Electrochemical transformation nitrate to ammonia at ambient conditions is a green alternative approach to the conventional Haber-Bosch process, while suffering from a restricted ammonia yield rate owing to the multi-step electron and proton transfer. Herein, we reported a quintessential bubble-like iron phosphides nanoparticles anchored on N-doped carbon framework (FeP@NC) electrocatalyst for nitrate reduction reaction (NO3RR). The FeP@NC catalyst exhibits 93.12 % NH3 faradaic efficiency (FE) at −0.5 V with the yield rate of 626.07 mmol h−1 gcat−1, superior over these for Fe@NC. DFT calculations indicate that the phosphorization promotes the absorption of NO3− and following hydrogenation, beneficial for NO3RR. This study provides a reference of transition metal phosphides for efficient NO3− removal and conversion.

Oxygen Vacancy and Heterostructure Modulation of Co2P/Fe2P Electrocatalysts for Improving Total Water Splitting.

Designing a stable and highly active catalyst for hydrogen evolution and oxygen evolution reactions (HER/OER) is essential for the industrialization of hydrogen energy but remains a major challenge. This work reports a simple approach to fabricating coupled Co2P/Fe2P nanorod array catalyst for overall water decomposition, demonstrating the source of excellent activity in the catalytic process. Under alkaline conditions, Co2P/Fe2P heterostructures exhibit an overpotential of 96 and 220 mV for HER and OER, respectively, at 10 mA cm-2. For total water splitting, a low voltage of 1.56 V is required to provide a current density of 10 mA cm-2. And the catalyst exhibits long-term durability for 30 h at a high current density of 250 mA cm-2. The analysis of the results revealed that the presence of interfacial oxygen vacancies and the strong interaction between Co2P/Fe2P provided the catalyst with more electrochemically active sites and a faster charge transfer capability, which improved the hydrolysis dissociation process. Electrochemically active metal (oxygen) hydroxide phases were produced after OER stability testing. The results of this study prove its great potential in practical industrial electrolysis and provide a reasonable and feasible strategy for the design of nonprecious metal phosphide electrocatalysts.

Patterns and outcomes of acute toxicological cases before, during, and after COVID-19 lockdown in Sohag University hospitals, Egypt.

Toxicologists manage poisoning by preventing, detecting, and treating it, which requires continuous data collection and analysis of toxicological hazards. The study aims to report and compare the pattern and outcome of acute toxicological cases admitted to Sohag University Hospitals during the COVID-19 lockdown (2020-2021) with the year before (2019) and the year after (2022). This comparative study reviewed the sociodemographic and clinical data in the medical records. The study showed that Sohag University Hospitals received 670 toxicological cases between 2019 and 2022; 105 cases in 2019, 347 cases in 2020-2021, and 218 cases in 2022. Most of patients were below seven years with no sex differences. Accidental poisoning was the most frequent toxicity. The oral route was the most common in the three studied periods. During the lockdown, metal phosphide was the most frequent (19.0%), while therapeutic agents were the most reported after the lockdown (23.9%). The delay time showed a significant difference between the studied periods (p-value<0.001). In the three studied periods, complete recovery was achieved in more than 70% of cases; however, the mortality rate and the rate of complications during the lockdown period (10.4% and 9.5%, respectively) were almost twice those of the year before and the year after the pandemic with significant odds ratio of mortality during pandemic (OR) 0.07 CI 95% (0.02, 0.11). The pandemic had a bad impact on outcomes as showed the highest percentage of mortality compared to before and after COVID-19 periods.

Preparation and application research of transition metal phosphides

Due to the serious environmental pollution in the world, the shortcut to harmonious development is to improve traditional disposable energy and identify new energy sources that can be utilized. The current problem that human society must solve is to discover and use efficient and inexhaustible new energy sources, among which electrolytic water technology is an effective way to develop clean energy. In recent years, researchers have focused on producing hydrogen by electrolyzed water, but the intermediate hydrogen evolution reaction and the oxygen evolution reaction are relatively slow kinetic processes, and they cannot give the factory a large range of electrolytic water hydrogen production work and push down the commercialization process, so improving the rate of electrolytic water process must be an efficient catalyst. Transition metal phosphide is one of the non-precious metal catalysts in the electrochemical hydrogen evolution reaction and oxygen evolution reaction. Transition metal phosphide can promote rapid change of chemical reaction rate, and it has the characteristics of being cheap and easy to operate so it has a great prospect in the electrolysis of water. In this experiment, the oxygen evolution performance was optimized based on the crystal surface regulation of cobalt-doped transition metal nickel phosphide. The optimal reduction time and a small overpotential (60 mV) were obtained by using sodium borohydride to reduce the sample.

Interfacial Chemistry and Catalysis of Inorganic Materials.

Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields.

Hydrogen evolution reaction activity enhancement from active site turnover mechanism

Although heteroatom doping is an effective way to improve the catalytic activity of transition metal phosphides (TMPs), the mechanism of activity enhancement needs to be further refined. To this end, we synthesized a Co-doped Ni2P catalyst as a research model and found that the introduction of heterogeneous Co reconstructed the charge distribution around the P site, which effectively enhanced the hydrogen evolution reaction (HER) activity of the pure Ni2P. Based on in-situ Raman real-time monitoring technology, we monitored for the first time that Co doping triggered a switch of the active site (from the original Co-active site to the P-active site), which promoted the adsorption of H2O to enhance the HER activity. The density functional theory (DFT) calculations indicated that the P site of Co-Ni2P expressed the highest activity and the Ni site of pure Ni2P expressed the highest activity, which further confirms the in-situ Raman monitoring results. The active site turnover mechanism discovered in this study will undoubtedly provide more rational and targeted ideas for future catalyst design.

Theoretical and experimental investigation on electrostatic field dynamics of Co3O4@NiPx electrocatalyst with core shell structure in overall water splitting reactions

Transition metal phosphides (TMPs) with platinum like electronic structures are becoming a potential choice to constructing bifunctional catalysts operated under alkaline conditions. Nevertheless, the instability of TMP prevents a further enhancement on its electrocatalytic activity. In this study, the Co3O4 core was first formed through thermal annealing in air, and then the outer NiPx layer was formed through the P-method, cleverly integrating the properties of the inner and outer materials and supplementing respective shortcomings, ultimately improving their water decomposition performance. When Co3O4@NiPx is used as a bifunctional electrocatalyst in 1 M KOH, the HER performance is determined to be 99 mV (η10). The electrocatalytic performance for oxygen evolution reaction (OER) is 249 mV (η50). For overall water decomposition, the bifunctional electrocatalysts Co3O4@NiPx coupled dual electrode alkaline battery only requires 1.51 V to obtain η50 and maintains its excellent electrocatalytic ability for 50 h. Finally, a combination of electrostatic field theory analysis and DFT calculations was used, the results indicated that the stability of core–shell materials can be significantly enhanced through Co3O4 core and internal electron redistribution by P atoms, thereby improving catalytic performance. The greatly improved electrochemical performance of Co3O4@NiPx indicates the rationality of the design and synthesis of the core–shell structure. The combination of electrostatic field theory analysis and DFT calculation also further reveals the rationality of its internal electrocatalytic mechanism.

Carbon Covering Method to Enhance the Storage Capacity of Materials Belonging to the Conversion and Alloy Storage Types

AbstractDriven by the development of energy storage systems (EESs), finding alternative anode materials forlithium‐ion batteries to replace the general carbon materials is becoming a hot research topic in the world. Using the metal oxides, metal sulfides, metal phosphides, metal selenides belonging to the conversion type and Sn, Sb, Bi, Ge, P and Si belonging to the alloy storage type seems to be a preferred option. Nevertheless, the demerits such as volume expansion and bad conductivity of alternative materials restrict their practical application. Carbon covering is an efficacious strategy to deal with the aforementioned issues because it can restrict the volume expansion and improve the conductivity of the composite materials effectively. This present review paper comprehensively describes the suitable carbon resources and preparation methods for expanding the practical applications of materials belonging to the conversion type and ally type in fabrications of negative electrodes.

NiCoP fibers as novel catalysts for hydrogen evolution in alkali and acidic environment

NiCoP transition metal phosphide has been recognized as a most promising candidate to alternate the noble metals in hydrogen evolution reaction. Herein, it is first time presented the facile preparation of NiCoP electrocatalyst in form of fibers with dominant 1D structure formed by needle-less electrospinning technology and finalized by defined heat treatment process. The study provides a precise method for the preparation of NiCoP or similar phosphide fibers, together with an experimental proof of their excellent electrocatalytic performance in alkali and acidic environments. The as-prepared fibrous NiCoP electrocatalyst sintered in air at 900 °C followed by sintering at 700 °C in Ar/H2 exhibits low hydrogen evolution reaction overpotential (η10) of 141 mV in alkali and 146 mV in acidic environment corresponding with low Tafel slopes of 53 and 97.8 mV/dec, respectively. The bimetallic phosphide also shows superior oxygen evolution reaction activity in alkaline medium 1 M KOH with satisfying durability in long-term stability tests. The highly innovative fibrous form of the material not only plays a significant role in regulation of the electronic structure and boosting the electrochemical active sites and thus the electrocatalytic performance in water splitting technology, but also allows tuning of the electrode electric conductivity, occurrence of the active sites probability and thus utilisation of the electrode, together with its permeability and mechanical stability.

Three-dimensional heterostructured MnNiCoP/FeOOH cross-linked nano-flake supported by Ni Foam as a bifunctional electrocatalysts for overall water splitting

The production of three-dimensional heterogeneous structures is a vital approach for the creation of high-performance bifunctional electrocatalysts. Herein, three-dimensional heterostructure MnNiCoP/FeOOH (MNC-P/FeOOH) supported by Ni foam was prepared by simple electrodeposition and phosphorylation as a bifunctional electrocatalyst. The results showed that the required overpotential for MNC-P/FeOOH catalyst to reach 100 mA cm−2 current density was 124 mV and 251 mV in 1.0 M KOH solution, respectively. Construction of heterojunction not only improves the OER performance of MnNiCoP, but also reduces the potential required to drive the integral water splitting at 100 mA cm−2 current density. The electrocatalytic activity of MNC-P/FeOOH is greatly increased due to a distinctive interface synergy and strong electronic contacts in the MNC-P/FeOOH heterojunction. This design approach of bifunctional transition metal phosphides provides a potential route to achieve total water splitting.

Noble Metal Phosphides Supported on CoNi Metaphosphate for Efficient Overall Water Splitting.

Transition metal metaphosphates and noble metal phosphides prepared under similar conditions are potential hybrid catalysts for electrocatalytic water splitting, which is of great significance for H2 production. Herein, the structure and electrocatalytic activity of different noble metal species (i.e., Rh, Pd, Ir) on CoNiP4O12 nanoarrays have been systematically studied. Due to the different formation energies of noble metal phosphides, the phosphides of Rh (RhPx) and Pd (PdPx) as well as the noble metal Ir are obtained under the same phosphorylation conditions perspectively. RhPx/CoNiP4O12 and PdPx/CoNiP4O12 exhibit much better HER activity than Ir/CoNiP4O12 due to the advantages of phosphides. Density functional theory (DFT) calculations reveal that the extraordinary activity of RhPx/CoNiP4O12 originated from the strong affinity to H2O and optimal adsorption for H*. The best RhPx/CoNiP4O12 only requires a low overpotential of 30 and 234 mV to deliver 10 mA cm-2 for HER and OER, respectively, and therefore is effective for overall water splitting (requiring 1.57 V to achieve a current density of 10 mA cm-2). This work not only develops a novel RhPx/CoNiP4O12 electrocatalyst for overall water splitting but also provides deep insight into the formation mechanism of noble metal phosphides.

Bulk‐Heterojunction Electrocatalysts in Confined Geometry Boosting Stable, Acid/Alkaline‐Universal Water Electrolysis

AbstractAlkaline water splitting electrocatalysts have been studied for decades; however, many difficulties remain for commercialization, such as sluggish hydrogen evolution reaction (HER) kinetics and poor catalytic stability. Herein, by mimicking the bulk‐heterojunction morphology of conventional organic solar cells, a uniform 10 nm scale nanocube is reported that consists of subnanometer‐scale heterointerfaces between transition metal phosphides and oxides, which serves as an alkaline water splitting electrocatalyst; showing great performance and stability toward HER and oxygen evolution reaction (OER). Interestingly, the nanocube electrocatalyst reveals acid/alkaline independency from the synergistic effect of electrochemical HER (cobalt phosphide) and thermochemical water dissociation (cobalt oxide). From the spray coating process, nanocube electrocatalyst spreads uniformly on large scale (≈6.6 × 5.6 cm2) and is applied to alkaline water electrolyzers, stably delivering 600 mA cm−2 current for &gt;100 h. The photovoltaic‐electrochemical (PV‐EC) system, including silicon PV cells, achieves 11.5% solar‐to‐hydrogen (STH) efficiency stably for &gt;100 h.

Transition metal phosphides: synthesis nanoarchitectonics, catalytic properties, and biomass conversion applications.

Developing inexpensive and efficient catalysts for biomass hydrogenation or hydrodeoxygenation (HDO) is essential for efficient energy conversion. Transition metal phosphides (TMPs), with the merits of abundant active sites, unique physicochemical properties, tunable component structures, and excellent catalytic activities, are recognized as promising biomass hydrogenation or HDO catalytic materials. Nevertheless, the biomass hydrogenation or HDO catalytic applications of TMPs are still limited by various complexities and inherent performance bottlenecks, and thus their future development and utilization remain to be systematically sorted out and further explored. This review summarizes the current popular strategies for the preparation of TMPs. Subsequently, based on the structural and electronic properties of TMPs, the catalytic activity origins of TMPs in biomass hydrogenation or HDO is elucidated. Additionally, the application of TMPs in efficient biomass hydrogenation or HDO catalysis, as well as highly targeted multiscale strategies to enhance the catalytic performance of TMPs, are comprehensively described. Finally, large-scale amplification synthesis, rational construction of TMP-based catalysts and in-depth study of the catalytic mechanism are also mentioned as challenges and future directions in this research field. Expectedly, this review can provide professional and targeted guidance for the rational design and practical application of TMPs biomass hydrogenation or HDO catalysts.

Metal Phosphide Anodes in Sodium-Ion Batteries: Latest Applications and Progress.

Sodium-ion batteries (SIBs), as the next-generation high-performance electrochemical energy storage devices, have attracted widespread attention due to their cost-effectiveness and wide geographical distribution of sodium. As a crucial component of the structure of SIBs, the anode material plays a crucial role in determining its electrochemical performance. Significantly, metal phosphide exhibits remarkable application prospects as an anode material for SIBs because of its low redox potential and high theoretical capacity. However, due to volume expansion limitations and other factors, the rate and cycling performance of metal phosphides have gradually declined. To address these challenges, various viable solutions have been explored. In this paper, the recent research progress of metal phosphide materials for SIBs is systematically reviewed, including the synthesis strategy of metal phosphide, the storage mechanism of sodium ions, and the application of metal phosphide in electrochemical aspects. In addition, future challenges and opportunities based on current developments are presented.

RuCo@P Core-Shell Nanoparticles Filled with Carbon Nanotubes for Highly Effective Catalytic Hydrolysis of Ammonia Borane

The doping of nonmetals in multiphase metal catalysts can effectively improve the catalytic performance and reduce the catalyst cost. In this study, we synthesized transition metal phosphide (RuCo@P/CNT) catalysts loaded on carbon nanotubes (CNT) using sodium borohydride (NaBH4) as the reducing agent. The microstructure and phase composition of RuCo@P/CNT nanoparticles were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and BET. RuCo@P/CNT nanoparticles show superior catalytic activity and cycle stability in the catalytic ammonia borane hydrolysis process compared to Ru/CNT and RuCo/CNT nanoparticles, retaining 65.74% of their initial catalytic activity after 5 reaction cycles. The test yielded values for turnover frequency and activation energy of 327.33 min-1 and 36.77 kJ·mol-1, respectively. Additionally, a kinetic isotope effect value of 2.61 for H2O/D2O showed that O-H bond breaking in proportional acceptor water is the decisive step in the dehydrogenation of ammonia borane, and based on this discovery, a specific mechanism for the catalytic hydrolysis of AB by RuCo@P NPs is postulated.

Self-Assembled Preparation of Porous Nickel Phosphide Superparticles with Tunable Phase and Porosity for Efficient Hydrogen Evolution.

Self-assembly of colloidal nanoparticles enables the easy building of assembly units into higher-order structures and the bottom-up preparation of functional materials. Nickel phosphides represent an important group of catalysts for hydrogen evolution reaction (HER) from water splitting. In this paper, the preparation of porous nickel phosphide superparticles and their HER efficiencies are reported. Ni and Ni2P nanoparticles are self-assembled into binary superparticles via an oil-in-water emulsion method. After annealing and acid etching, the as-prepared Ni-Ni2P binary superparticles change into porous nickel phosphide superparticles. The porosity and crystalline phase of the superparticles can be tuned by adjusting the ratio of Ni and Ni2P nanoparticles. The resulting porous superparticles are effective in driving HER under acidic conditions, and the modulation of porosity and phase further optimize the electrochemical performance. The prepared Ni3P porous superparticles not only possess a significantly enhanced specific surface area compared to solid Ni-Ni2P superparticles but also exhibit an excellent HER efficiency. The calculations based on the density functional theories show that the (110) crystal facet exhibits a relatively lower Gibbs free energy of hydrogen adsorption. This work provides a self-assembly approach for the construction of porous metal phosphide nanomaterials with tunable crystalline phase and porosity.