Iron Phosphide Nanoparticles Research Articles

Iron phosphide nanoparticles anchored on 3D nitrogen-doped graphene as an efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Electrocatalysts play a crucial role in hydrogen evolution reaction (HER), facilitating a clean and sustainable generation of hydrogen energy. To promote the HER process, it is imperative to employ highly efficient, stable, and cost-effective electrocatalysts. This research focuses on the design of iron phosphide nanoparticles anchored onto a porous three-dimensional nitrogen-doped graphene (FeP@3DNG). The porous framework of 3DNG serves a multifaceted purpose: it prevents the aggregation of FeP nanoparticles during phosphidation, safeguards the FeP electrocatalyst from oxidation during the HER, and simultaneously enhances electrical conductivity and stability. Notably, the FeP@3DNG nanocomposite demonstrated the efficient activity and highest HER activity with an overpotential of 76 mV to achieve 10 mA cm−2 and a small Tafel slope of 40.2 mV dec−1 as well as good long-term durability for 20 h in 1.0 M KOH solution. The high performance of the FeP@3DNG nanocomposite can be primarily corresponded to the synergistic effects of the highly active of FeP nanoparticles and advantages of porous three-dimensional graphene with excellent electrocatalytic activity, high specific surface area, and chemical stability, thus, resulting in the improvement the overall electrocatalytic activity.

Identification of true active sites in N-doped carbon-supported Fe2P nanoparticles toward oxygen reduction reaction

Transition metal-based nanoparticles (NPs) are emerging as potential alternatives to platinum for catalyzing the oxygen reduction reaction (ORR) in zinc-air batteries (ZAB). However, the simultaneous coexistence of single-atom moieties in the preparation of NPs is inevitable, and the structural complexity of catalysts poses a great challenge to identifying the true active site. Herein, by employing in situ and ex situ XAS analysis, we demonstrate the coexistence of single-atom moieties and iron phosphide NPs in the N, P co-doped porous carbon (in short, Fe-N4-Fe2P NPs/NPC), and identify that ORR predominantly proceeds via the atomic-dispersed Fe-N4 sites, while the presence of Fe2P NPs exerts an inhibitory effect by decreasing the site utilization and impeding mass transfer of reactants. The single-atom catalyst Fe-N4/NPC displays a half-wave potential of 0.873 V, surpassing both Fe-N4-Fe2P NPs/NPC (0.858 V) and commercial Pt/C (0.842 V) in alkaline condition. In addition, the ZAB based on Fe-N4/NPC achieves a peak power density of 140.3 mW cm−2, outperforming that of Pt/C-based ZAB (91.8 mW cm−2) and exhibits excellent long-term stability. This study provides insight into the identification of true active sites of supported ORR catalysts and offers an approach for developing highly efficient, nonprecious metal-based catalysts for high-energy–density metal-air batteries.

Synergistic impact of dual active sites in Nb-Fe2P nanoparticles on electrocatalytic nitrate reduction with high selectivity

The electrochemical transformation of nitrate into ammonia offers a promising alternative to the traditional Haber-Bosch process. The nitrate reduction reaction (NO3–RR) involves complex multi-electron/proton processes and faces competition from hydrogen evolution reactions, leading to low Faraday efficiency and diminished ammonia production. This study introduces carbon-supported niobium-doped iron phosphide nanoparticles (Nb-Fe2P) electrocatalysts, synthesized using deep eutectic solvent (DES). These electrocatalysts achieved an exceptional ammonia yield of 9.7 mg h−1 cm−2 and a Faraday efficiency of 95.8 % in the NO3–RR. Both experimental and theoretical studies reveal that the dual active sites of Fe and Nb significantly enhance the generation of active hydrogen and expedite the utilization of nitrogen-containing intermediates. This innovative approach, focusing on active hydrogen balance, offers a strategic pathway for developing highly efficient NO3–RR electrocatalysts by promoting the dissociation of H2O.

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.

Construction of 3D carbon dots/Prussian blue analogue-derived phosphide nanocomposites on Ni foam for high-performance supercapacitors

A desirable electrode material with rational architecture and superior composition is the key to optimize the electrochemical performance of supercapacitor. Prussian blue analogues are a kind of promising precursors for electrode preparation with the features of adjustable compositions and rigid frame structure. In this work, carbon dots/nickel iron phosphide nanoparticles grown on Ni foam have been delicately designed and synthesized from PBAs for the application of cathode of hybrid supercapacitors (HSC). Introduction of CDs is found that not only favors the nanocubes growth of PBAs precursor but also alleviates aggregation of the nanocubes during calcination and phosphorization. The uniform coverage of carbon dots on the phosphides offers hydrophilic interfaces beneficial to the interaction between electrodes and electrolyte and improves the chemical stability of the electrodes. With these assets, the optimum electrode exhibits remarkable areal capacitance (2589 mF cm−2 at a current density of 2 mA cm−2), noteworthy rate performance and excellent cycling stability. Moreover, the as-fabricated hybrid supercapacitor shows a high energy density and power density, as well as high stability. These results indicate that the CDs/NiFeP-NF electrode has the desirable potential to be a candidate for energy storage devices. The structure modulation in this work may provide a new avenue for development of PBAs-based phosphides materials in the field of energy conversion and storage.

Synthesis of iron phosphide nanoparticles dispersed in activated carbon and their application in Fenton processes

Synthesis of iron phosphide nanoparticles dispersed in activated carbon and their application in Fenton processes

Design of nanocatalyst for electrode structure: Electrophoretic deposition of iron phosphide nanoparticles to produce a highly active hydrogen evolution reaction catalyst

• FeP NP electrocatalytic electrode was fabricated via electrophoretic deposition. • Morphology and porosity of catalyst layer were tuned by altering deposition kinetics. • Optimized porosity/catalyst loading lead to the excellent HER activity. • The HER electrode was successfully applied as cathode GDE of high performance PEMWE. The inherent properties of nanoparticles (NPs) can be engineered into macroscopic structures by capturing the collective characteristics of the nanomaterials via a fabrication process to realize macroscopic functionality. Herein, we report a powerful manufacturing technique for fabricating an electrode composed of highly porous iron phosphide (FeP) NP catalyst layers conformally deposited on macroporous Carbon paper (CP) that shows excellent hydrogen evolution reaction activity. The surface morphology and porosity of the FeP NP catalyst layers on the FeP/CP electrode were tuned by altering the deposition kinetics of the colloidal FeP NPs by controlling the solvent system in the electrophoretic deposition process. The FeP/CP electrode achieved a low overpotential of 38 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 due to the highly exposed catalytic surface with a high catalyst loading amount and fast charge transfer. When the FeP/CP electrode was applied as a cathode gas diffusion electrode in a proton exchange membrane water electrolyzer, the single-cell exhibited excellent operating performance (1.48 A cm −2 @ 2.0 V cell , 90 °C). Our results illustrate a facile route for fabricating nanostructured macroscale devices by maximizing the collective properties of the nanoscale materials.

Insights into the Effect of Precursors on the FeP-Catalyzed Hydrogen Evolution Reaction.

Iron phosphide nanoparticles (NPs) are promising noble metal-free electrocatalysts for the hydrogen evolution reaction (HER), but they usually show inferior activity due to the limited surface area and oxidative passivation. We reported a facile synthetic method to prepare FeP hollow NPs (HNPs) with various precursors. It was proven that the structural parameters (i.e., size, phosphating temperature, phase, and surfactant) of oxide precursors were correlated to the electrochemically active surface area (ECSA), phase purity, surface oxidation, and hollow morphology of FeP HER catalysts, thus affecting the HER activity. Among the three FeP HNPs, the 9 nm FeP HNPs prepared using the Fe3O4 precursor exhibited the highest overall activity with the lowest overpotential of 76 mV to drive a cathodic current density of 10 mA·cm-2 due to the highest ECSA, while 25 nm FeP prepared using the Fe2O3 precursor showed the highest turnover frequency because of the high phase purity and low surface oxidation degree.

Biomass-based porous materials encapsulating Iron phosphide nanoparticles for enhanced contaminant removal via peroxymonosulfate activation

The highly efficient biochar-based catalysts from agricultural biomass wastes receive tremendous interest in the wastewater restoration field because of lower cost and environmental friendliness. Herein, the abundant agricultural waste loofah sponge is used as the precursor to prepare eco-friendly carbonized loofah sponge encapsulating Iron Phosphide nanoparticles (CLS-IP) by a facile pyrolysis strategy. The as-synthesized CLS-IP not only exhibited excellent catalytic activity for Acid Red 1 removal via activating peroxymonosulfate (PMS), which achieved 94.4% removal in 24 min, but also removed other common pollutants including phenolic compounds, sulfonamides, and dyes. Besides, the iron ions leaching (0.03–0.19 ppm) was obviously lower than 2.00 ppm according to European standard even after reuse. Surprisingly, the used CLS-IP catalyst could be effectively regenerated after the oxalic acid immersion treatment. In addition, the CLS-IP still exhibited remarkable catalytic activity even after five months of storage. Four types of reactive oxygen species (ROS) including hydroxyl radical (•OH), sulfate radical (SO4•−), superoxide radical (O2•−), and singlet oxygen (1O2) were generated during the reaction, and the superoxide radical made a dominant contribution. This work provided an avenue for developing low-cost biochar-based catalysts in environmental remediation.

A Single Molecular Stoichiometric P‐Source for Phase‐Selective Synthesis of Crystalline and Amorphous Iron Phosphide Nanocatalysts

AbstractThe formation of iron phosphide nanoparticles (FexP NPs) is a well‐studied process. It usually uses air‐sensitive phosphorus precursors such as n‐trioctylphosphine or white phosphorus. In this study, we report the synthesis and characterization of a remarkably stable tetrakis(acyl)cyclotetraphosphane, P4(MesCO)4. We demonstrate that this compound can be used as a stoichiometric source of P(0) species in order to synthesize FeP and Fe2P nanoparticles at only 250 °C. This tunable process provides a route to monodisperse nanoparticles with different compositions and crystallinities. We combine X‐Ray photoelectron spectroscopy (XPS) and atomic pair distribution function (PDF) in order to study the local order and bonding in the amorphous and crystalline materials. We show that crystalline FeP forms via an intermediate amorphous phase (obtained at a lower temperature) that presents local order similar to that of the crystalline sample. From the results of this work, a better understanding of the mechanism of the formation of amorphous and crystalline FexP NPs is provided which relies on the use of a stoichiometric and single P‐source. We then explore the electrocatalytic properties of FexP nanoparticles for the hydrogen evolution reaction (HER) in acidic and neutral electrolytes. In both electrolytes, amorphous FeP is a more efficient catalyst than crystalline FeP, itself more efficient than crystalline Fe2P. Our study paves the way for a more systematic investigation of amorphous metal phosphide phases in electrocatalysis. It also shows the beneficial properties of PDF on the characterization of such nanomaterials, which is highly challenging.

One-pot synthesis of magnetic iron phosphide nanoparticles

A novel one-pot synthetic method to produce crystalline tri-octylphosphine (TOP) capped iron phosphide nanoparticles is reported here. Standard method of synthesizing FeP includes preparation of a precursor, sodium phosphide, which is finally reacted with ferric chloride (FeCl3).The methods for synthesizing iron phosphide (FeP), reported so far, rely on the use of toxic red or yellow phosphorus to generate the precursor, Sodium phosphide (Na3P). In present investigation, instead of red or yellow phosphorus, a relatively less toxic substance TOP and sodium metal (Na) have been used to yield Na3P. The synthesized nanoparticles were fully characterized by X-ray diffraction pattern (XRD), Infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM) and superconducting quantum interference device (SQUID) analyses. The results showed that the synthesized FeP nanoparticles have the characteristic orthorhombic crystal structures, with the size ∼10 nm and the coercivity 70 Oe at RT.

Transition metal-doped FeP nanoparticles for hydrogen evolution reaction catalysis

Transition-metal phosphides have been investigated as promising materials for hydrogen evolution reaction (HER) catalysts because of their cost efficiency, high catalytic activity, and good stability. Here, we report the spherical iron phosphide nanoparticles (FeP NPs) doped with various transition metals (Mn, Co, and Ni) via a phosphorization process from Fe-based bimetallic NPs and characterize the changes in their HER activity as a result of doping with different elements. Electrochemical measurements indicated that the Co-FeP NPs exhibited an overpotential of 126 mV to achieve a 10 mA cm−2, demonstrating higher activity than the FeP, Ni-FeP, and Mn-FeP NPs because of their large active surface area and fast charge transfer. X-ray photoelectron spectroscopy analysis showed that the Co-FeP NPs exhibit a significantly tuned chemical state through the presence of more metal–P bonds and fewer oxidized species compared with the other doped products. In addition, X-ray diffraction and X-ray absorption spectroscopy analysis revealed substitutional doping of Fe atoms by Co atoms in the FeP crystalline structure. This study provides new insights for the efficient synthesis of doped transition-metal phosphides and for designing nanocatalysts with enhanced catalytic activity.

Iron phosphide nanoparticles as a pH-responsive T 1 contrast agent for magnetic resonance tumor imaging.

In this work, the potential of FeP nanoparticles as a pH-responsive T1 contrast agent was investigated. The FeP nanoparticles have good biocompatibility and can significantly amplify T1 magnetic resonance signals in response to the acidic microenvironment of solid tumors, holding great promise in serving as an acid-activatable T1 contrast agent for tumor imaging.

Cobalt iron phosphide nanoparticles embedded within a carbon matrix as highly efficient electrocatalysts for the oxygen evolution reaction.

Co3FePx/C nanocomposites were derived from one-step phosphorization of anthraquinone-2-sulfonate (AQS2) intercalated Co3Fe layered double hydroxides (Co3Fe LDHs). The carbonized AQS2 confines Co3FePx nanoparticles in the amorphous carbon matrix during thermal treatment. Ultra-small and uniformly distributed Co3FePx/C nanoparticles in carbon exhibit excellent durability and outstanding OER catalytic activity.

Phase transformation of iron phosphide nanoparticles for hydrogen evolution reaction electrocatalysis

Transition metal phosphides have emerged as alternative electrocatalysts for hydrogen evolution reaction (HER) due to their high activity and low cost compared to the conventional HER electrocatalysts such as Pt. However, the dependency of HER activity on different crystal phases is not well-understood. Here, we synthesized iron phosphide nanoparticles with two distinct phases via chemical transformation from iron metal to iron phosphides. During the development of iron phosphide phases by varying the synthesis conditions such as reaction temperature and time, the HER activities of the nanoparticle were examined. The HER activities of the iron phosphide nanoparticles were found to be phase-dependent.

Prussian Blue-Derived Iron Phosphide Nanoparticles in a Porous Graphene Aerogel as Efficient Electrocatalyst for Hydrogen Evolution Reaction.

Tailoring of new hydrogen evolution reaction (HER) electrocatalyst with earth abundant elements is important for large scale water splitting and hydrogen production. In this work, we present a simple synthetic method for incorporating iron phosphide (FeP) particles into three-dimensional (3D) porous graphene aerogel (GA) structure. The FeP formed in porous 3D GA (FeP/GA) is derived from electroactive Fe hexacyanoferrate (FeHCF). The advantage of incorporating FeP, in the porous 3D graphene network enables high accessibility for HER. As synthesized FeP/GA catalyst shows good electrocatalytic activity for HER in both acidic and alkaline solutions. The developed method can be useful for synthesizing metal hexacyanoferrate derived mono/bimetal phosphide catalyst in porous 3D graphene aerogels.

Controllable synthesis of carbon encapsulated iron phosphide nanoparticles for the chemoselective hydrogenation of aromatic nitroarenes to anilines

Iron phosphide nanoparticles encapsulated in a doped carbon matrix showed high activity and good selectivity in the hydrogenation of aromatic nitroarenes to anilines.

Iron Phosphide Nanoparticles As an Efficient Electrocatalyst for the Oxygen Evolution Reaction in Alkaline Solution

Splitting water to hydrogen and oxygen through hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is basis to feed the fuel cell. OER is a thermodynamically uphill process as it requires higher potential to form O2 molecule. The best known catalysts to split water with low overpotential are the oxides of Ir and Ru. As these catalysts are precious metals there has been intensive research to substitute them with earth-abundant resources. The new catalyst should fulfill the following: (i) the catalyst to split water has to use minimal energy (measured as applied voltage and referred to as overpotential); (ii) should comprise of earth abundant elements; (iii) should be stable; (iv) should be scalable.1 Transition metal oxides have been recently identified as high-efficiency catalysts for oxygen and/or hydrogen evolution reaction. Apart from the oxides there has been reports of sulfide, selenide and nitride based catalysts.2 Although transition metal phosphides has recently gathered attention as HER catalysts,3 very less metal phosphides have been reported as OER electrocatalyst. In this presentation, ultra-small iron phosphide nanoparticles as well nanoparticle composite with reduced graphene oxide (FeP-rGO) has been reported as efficient electrocatalysts for OER under alkaline conditions. FeP nanoparticles require an overpotential of 290 mV @ 10 mAcm-2. It is well known that rGO is a good conductor and a support material for the catalysts. Hence, mixing of FeP nanoparticles with rGO has improved the catalytic efficiency further by reducing the overpotential to 260 mV to achieve 10 mAcm-2 current density4. The FeP nanoparticles and FeP-rGO composite showed the lowest overpotential at 10 mA/cm2 that has observed among the pnictide making these the most-efficient phosphide based OER catalyst till date. The hybrid catalyst showed a low Tafel slope of 50.8 mV/dec. The stability of the catalyst was excellent with 4h of continuous oxygen evolution and the catalytic activity was retained with a similar overpotential @ 10 mAcm-2. The synthesis of hybrid catalysts, detailed characterization, and electrochemical studies including liner scan voltammetry (LSV), choronoamperometry will be discussed in detail.

Iron phosphide nanoparticles as an efficient electrocatalyst for the OER in alkaline solution

Ultrasmall FeP nanoparticles have been reported as an efficient oxygen evolution electrocatalyst in alkaline medium with low onset potential for oxygen evolution and require low overpotential to reach 10 mA cm−2 exchange current density.

Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles.

Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of -10 mA cm(-2), FeP nanoparticles deposited at a mass loading of ∼1 mg cm(-2) on Ti substrates exhibited overpotentials of -50 mV in 0.50 M H2SO4 and -102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods under galvanostatic control. Under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles deposited on TiO2 produced H2 at rates and amounts that begin to approach those of Pt/TiO2. FeP therefore is a highly Earth-abundant material for efficiently facilitating the HER both electrocatalytically and photocatalytically.