Cobalt Phosphide Nanoparticles Research Articles

Dual modification of cobalt silicate nanobelts by Co3O4 nanoparticles and phosphorization boosting oxygen evolution reaction properties

Oxygen evolution reaction (OER) process is the “bottleneck” of water splitting, and the low-cost and high-efficient OER catalysts are of great importance and attractive but they are still challenging. Herein, a dual modification strategy is developed to tune and enrich the structure of cobalt silicate (Co2SiO4) showing boosted OER properties. Cobalt oxide (Co3O4) decorated Co2SiO4 nanobelts, denoted as CS, is firstly prepared using a Co-based precursor by a facile hydrothermal reaction. Then, cobalt phosphide (CoP) nanoparticles are in-situ grown on CS (denoted as CS-P) by the phosphorization process, which provide many active sites and boost the surface reactivity. The experimental results and density function theory (DFT) calculations both reveal that the CoP on CS can improve the conductivity and ensure fast kinetics, thus leading to boost the OER properties of Co2SiO4. When the phosphorization temperature is at 400 °C (CS-P400), it gains the lowest overpotential of 297 mV, which is much lower than CS (340 mV) and Co2SiO4 (409 mV) at 10 mA·cm−2, and even superior to the state-of-the-art transition metal silicates. CS-P400 also achieves high electrochemical active surface area (ECSA) and small Tafel slope owing to its porous structures with large specific surface area and nanosheet-like structures which are good for exposing many active sites and favorable to the fast kinetics. This work not only provides a dual modification route to boost catalytic activity of Co2SiO4 (CS-P400), but also sheds light on a new avenue for developing highly dispersed CoP on silicates to boost OER performances.

Synergistic heterostructural interface of CoP and WC for high-performance wide pH-universal hydrogen evolution electrocatalysis

The development of cost-effective catalysts with high activity and stability over a wide pH range is urgent, but there are great challenges in the selection and design of catalyst materials. In this work, cobalt phosphide nanoparticles were modified onto tungsten carbide nanowire arrays (CoP@WC/CC) on carbon cloth substrate by a two-step method. The construction of CoP@WC heterostructure results in the downward shift of the d-band center, which optimizes the adsorption energy of catalyst and reaction intermediates. Meanwhile, the synergistic effect of CoP and WC contributes to the alkaline HER kinetic process. In addition, binder-free self-supporting nanoarray have excellent electrical conductivity, large specific surface area and strong structure, which is conducive to charge/matter exchange and catalyst stability. The results show that CoP@WC/CC can effectively drive HER over a wide pH range and exhibit better catalytic performance than the single component control sample. In 0.5 M H2SO4 and 1 M KOH, CoP@WC/CC can drive the current density of 10 mA cm−2 with only 52 and 70 mV, while showing excellent stability without obvious performance degradation during 100 h of constant current test. A proton exchange membrane water electrolysis (PEMWE) using CoP@WC/CC catalyst operates stably for 200,000 s at 30 mA cm−2. This study provides a new reference for the design and development of high efficiency, low cost and wide pH-universal hydrogen evolution electrocatalysts.

Size-controlled synthesis of cobalt phosphide (Co2P) nanoparticles and their application in non-enzymatic glucose sensors via a carbon fiber/Co2P composite

In this study, we synthesized Co2P nanoparticles using a solid-state phosphorization method and evaluated the electrocatalytic response to glucose oxidation reaction (GORs). The influence of synthesis conditions on the particle size, morphology of Co2P species and formation of byproducts is discussed. A lower molar ratio of the phosphorus precursor leads to a decrease in the generation of byproducts. In addition, the calcination temperature and time greatly influence the purity level of the Co2P species and its particle size. Thus, we obtained three pure Co2P nanoparticles with different sizes and morphologies. Significant differences in their electrocatalytic activity against the GOR are observed depending on the size of the particles, being the smaller ones the most efficient. Based on Tafel analysis, a higher catalytic activity was observed for the carbon fibre (CF)/Co2P composite compared to Co2P, which presented a greater onset potential and low response in current density. Tafel slopes close to 120 mV/dec were obtained for both materials, indicating that the mechanism is independent of the type of Co2P-based material used. Finally, the performance of the GCE/CF/Co2P sensor was demonstrated by amperometric measurements, with a sensitivity of 409 µAmM-1cm-2, a linear range between 39.4 µM and 150 µM, and a detection limit of 0.97 µM, analytical characteristics better than those obtained for other cobalt phosphide-based sensors reported in the literature. In addition, the GCE/CF/Co2P sensor shows excellent selectivity and demonstrated to be competitive compared to other Co-based non-enzymatic glucose sensors.

Construction of iron-doped nickel cobalt phosphide nanoparticles via solvothermal phosphidization and their application in alkaline oxygen evolution

Multi-metallic phosphides offer the possibility to combine the strategies of surface reconstruction, electronic interaction and mechanistic pathway tuning to achieve high electrocatalytic oxygen evolution activity. Here, iron-doped nickel cobalt phosphide nanoparticles (FexCoyNi2-x-yP) with the crystalline NiCoP phase are for the first time synthesized by the solvothermal phosphidization method via the reaction between metal–organic frameworks and white phosphorus. When used to electrochemically catalyze oxygen evolution reaction (OER), the Fe0.4Co0.8Ni0.8P supported by nickel foam requires only 248 mV overpotential to achieve 10 mA cm−2 current densities, and is robust towards the long-term OER in 1 M KOH. The higher number of electrochemically active sites can account for the good OER activity, along with the improved intrinsic activity which is caused by the electron interaction that optimizes the adsorption energy of hydroxyl intermediates, and that increases the acidity of high-valent metal centers. The OER mechanistic pathway involves both adsorbate and lattice oxygen. Surface conversion is observed after OER in alkaline solution, and metal phosphide layer transforms to metal oxides and (oxy)hydroxides.

Chalcogen-Based Precursors for Transition Metal (Co, Ni) Phosphides: (Di)chalcogenide-to-Phosphide Transformation via Chemical Extraction of Chalcogenides.

The chemical properties of polymorphic compounds are highly dependent on their stoichiometry and atomic arrangements, making certain phases technologically more important. Selective development of these phases is challenging. This study introduces a method where chalcogenide atoms from metal chalcogenides are chemically extracted by trioctylphosphine (TOP) and substituted with phosphide. Using this approach, dithiocarbamate/xanthate complexes of cobalt and nickel were employed for the selective synthesis of pure metal sulfides or phosphides. Optimization yielded either sulfur-deficient phases (Ni3S2, Co9S8) or a complete transformation to phosphides (Ni2P, CoP). Likewise, for the first time, selenobenzoate complexes of Ni and Co were used for the synthesis of transition metal diselenides (NiSe2, CoSe2), which could then be converted to metal phosphides (Ni2P, Co2P). The synthesis used solution-phase thermal decomposition with various precursors, surfactants, and temperatures. With TOP, different phases of metal chalcogenides, metal phosphides, and mixed metal phosphide nanomaterials (NiS, Ni3S2, Co9S8, NiSe2, CoSe2, Ni2P, Ni5P4, Co2P, CoP, and Ni2-xCoxP) were obtained by varying reaction conditions. The formation mechanism of nickel and cobalt phosphide nanoparticles from precursors is proposed, demonstrating that presynthesized metal chalcogenides can be transformed into phosphides, opening a new research avenue for dimensionally controlled metal chalcogenides as templates for metal phosphides.

Enabling Logistics Automation in Nanofactory: Cobalt Phosphide Embedded Metal-Organic Frameworks for Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate reduction reaction (NitRR) in neutral condition offers a promising strategy for green ammonia synthesis and wastewater treatment, the rational design of electrocatalysts is the cornerstone. Inspired by modern factory design where both machines and logistics matter for manufacturing, it is reported that cobalt phosphide (CoP) nanoparticles embedded in zinc-based zeolite imidazole frameworks (Zn-ZIF) function as a nanofactory with high performance. By selective phosphorization of ZnCo bimetallic zeolite imidazole framework (ZnCo-ZIF), the generated CoP nanoparticles act as "machines" (active sites) for molecular manufacturing (NO3 - to NH4 + conversion). The purposely retained framework (Zn-ZIFs) with positive charge promotes logistics automation, i.e., the automatic delivery of NO3 - reactants and timely discharge of NH4 + products in-and-out the nanofactory due to electrostatic interaction. Moreover, the interaction between Zn-ZIF and CoP modulates the Co sites into electron insufficient state with upshifted d-band center, facilitating the reduction/hydrogenation of NO3 - to ammonia and restricting the competitive hydrogen evolution. Consequently, the assembled CoP/Zn-ZIF nanofactory exhibits superior NitRR performances with a high Faraday efficiency of ≈97% and a high ammonia yield of 0.89mmol cm-1 h-1 in neutral condition, among the best of reported electrocatalysts. The work provides new insights into the design principles of efficient NitRR electrocatalysts.

Rational Construction of 3D Self-Supported MOF-Derived Cobalt Phosphide-Based Hollow Nanowall Arrays for Efficient Overall Water Splitting At large Current Density.

Developing efficient nonprecious bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) in the same electrolyte with a low overpotential and large current density presents an appealing yet challenging goal for large-scale water electrolysis. Herein, a unique 3D self-branched hierarchical nanostructure composed of ultra-small cobalt phosphide (CoP) nanoparticles embedded into N, P-codoped carbon nanotubes knitted hollow nanowall arrays (CoPʘNPCNTs HNWAs) on carbon textiles (CTs) through a carbonization-phosphatization process is presented. Benefiting from the uniform protrusion distributions of CoP nanoparticles, the optimum CoPʘNPCNTs HNWAs composites with high abundant porosity exhibit superior electrocatalytic activity and excellent stability for OER in alkaline conditions, as well as for HER in both acidic and alkaline electrolytes, even under large current densities. Furthermore, the assembled CoPʘNPCNTs/CTs||CoPʘNPCNTs/CTs electrolyzer demonstrates exceptional performance, requiring an ultralow cell voltage of 1.50V to deliver the current density of 10mAcm-2 for overall water splitting (OWS) with favorable stability, even achieving a large current density of 200mAcm-2 at a low cell voltage of 1.78V. Density functional theory (DFT) calculation further reveals that all the C atoms between N and P atoms in CoPʘNPCNTs/CTs act as the most efficient active sites, significantly enhancing the electrocatalytic properties. This strategy, utilizing 2D MOF arrays as a structural and compositional material to create multifunctional composites/hybrids, opens new avenues for the exploration of highly efficient and robust non-noble-metal catalysts for energy-conversion reactions.

Decorating N-doped carbon-coated cobalt phosphide nanoparticles onto N-doped carbon nanotubes for high-performance supercapacitors and efficient methanol electro-oxidation

Cobalt phosphide (CoP) has become a promising electrode material for supercapacitors and methanol electro-oxidation due to its high electrical conductivity and and multiple oxidation states. However, the insufficient electroactive sites and large volume changes restrict its electrochemical performance. Herein, a novel CoP/carbon nanocomposite electrode material is designed and synthesized by decorating N-doped carbon (NC) coated CoP nanoparticles onto N-doped carbon nanotubes (N-CNTs). N-CNTs serve as support to grow CoP nanoparticles, which effectively reduces the sizes and aggregation of CoP nanoparticles and provides more electroactive sites. Density function theory calculation results confirm that the coating of NC on CoP nanoparticles increases the electrical conductivity of CoP by transferring electrons from NC to CoP. Meanwhile, a built-in electrical field is formed at the CoP/NC interface, resulting in higher electron/ion transfer efficiency as well as easier surface OH– adsorption. Moreover, the flexible NC shell and N-CNTs supports together effectively withstand the mechanical stress and buffer volume changes of CoP during the charge/discharge processes. Therefore, the obtained N-CNTs@CoP@NC nanocomposite electrode demonstrates high specific capacities (1003 and 621C g−1 at 1 and 10 A g−1, respectively) and good cycling performance (91.2 % retention of initial capacity after 10,000 cycles at 5 A g−1). Furthermore, it also shows a current density of up to 281 mA cm−2at a scan rate of 10 mV s−1with 92.4 % retention of initial current density in 1 M KOH with 0.5 M methanol. These results highlight a feasible strategy for improving practical capacities and cyclic stability of CoP-based electrode materials by integrating nanostructured CoP with one/two-dimensional carbon materials.

Synergistic interfacial electronic modulation of topotactically developed bimetallic CoNiP on NiS nanorods for enhanced alkaline hydrogen evolution reaction.

Designing hybrid transition metal phosphosulfide electrocatalysts is critical for the hydrogen evolution reaction (HER). We propose a novel approach by designing a hierarchical structure of cobalt phosphide (CoP) and nickel phosphide (Ni8P3) nanoparticles topotactically developed on nickel sulfide (Ni3S2) nanorods (CoNiP/NiS) via a sulfuration-phosphorization strategy using conductive 3D nickel foam. Hierarchical heterostructured nanorods were achieved without the need for template removal steps or the assistance of surfactants. This not only simplifies the process but also improves the exposure of active sites for catalytic purposes. Furthermore, the theoretical calculation results revealed that the high H* adsorption-free energy for CoP and Ni8P3 phases significantly decreases upon coupling with Ni3S2, which indicates that the interfacial electronic interaction synergistically modulates both CoP and Ni8P3 (CoNiP) at the coupled interfaces and facilitates the adsorption and desorption of H* intermediates during the HER process. The resulting electrode exhibits excellent performance in the HER catalytic process and shows great performance for further exploration in the urea oxidation reaction (UOR). Our work provides a stepping stone toward rational topotactic transformation of active materials on porous substrates, using electronic structure regulation and heterointerfaces to produce promising electrocatalysts for sustainable, large-scale hydrogen production from water electrolysis.

Cobalt Phosphide Nanoparticles Supported by Vertically Grown Graphene Sheets on Carbon Black with N-Doping Treatment as Bifunctional Electrocatalysts for Overall Water Splitting

Cobalt Phosphide Nanoparticles Supported by Vertically Grown Graphene Sheets on Carbon Black with N-Doping Treatment as Bifunctional Electrocatalysts for Overall Water Splitting

Exploring Cobalt Phosphide Nanoparticles Sheathed within N-Rich Carbon Polyhedra as High-Capacity Anode for All-Solid-State Lithium-Ion Batteries

Exploring Cobalt Phosphide Nanoparticles Sheathed within N-Rich Carbon Polyhedra as High-Capacity Anode for All-Solid-State Lithium-Ion Batteries

A Green Synthesis Strategy for Cobalt Phosphide Deposited on N, P Co-Doped Graphene for Efficient Hydrogen Evolution.

The exploitation of electrocatalysts with high activity and durability for the hydrogen evolution reaction is significant but also challenging for future energy systems. Transition metal phosphides (TMPs) have attracted a lot of attention due to their effective activity for the hydrogen evolution reaction, but the complicated preparation of metal phosphides remains a bottleneck. In this study, a green fabrication method is designed and proposed to construct N, P co-doped graphene (NPG)-supported cobalt phosphide (Co2P) nanoparticles by using DNA as both N and P sources. Thanks to the synergistic effect of NPG and Co2P, the Co2P/NPG shows effective activity with a small overpotential of 144 mV and a low Tafel slope of 72 mV dec-1 for the hydrogen evolution reaction. This study describes a successful green synthesis strategy for the preparation of high-performance TMPs.

Ru-modified cobalt phosphide nanoparticles on N-doped carbon nanofibers for efficient hydrogen evolution reaction in alkaline media

Transition metal phosphides (TMPs) are a promising catalyst material for the hydrogen evolution reaction (HER). In this study, we introduced inexpensive red phosphorus (P4) into a homogeneous solution as a phosphorus source. Using the electrostatic spinning technique combined with high temperature carbonization, we successfully prepared self-supported carbon nanofibers doped with nitrogen (N) and loaded with ruthenium (Ru)-modified cobalt phosphide (Co2P) nanoparticles catalysts (Ru@Co2P/CNFs). The Ru@Co2P phosphide nanoparticles were evenly distributed on the surface of the carbon fibers, forming a three-dimensional network structure. The synergistic effect between the Ru and Co2P systems resulted in excellent catalytic activity and stability for the hydrogen evolution reaction in alkaline solutions. The N-doped conducting carbon matrix and large specific surface area of the active sites contributed to this enhanced performance. The Ru@Co2P/CNFs catalysts only required an overpotential of 48 mV at a current density of 10 mA cm−2, outperforming the noble metal platinum/carbon (Pt/C) catalysts, which required an overpotential of 52 mV. Furthermore, the Ru@Co2P nanoparticles were protected by a carbon layer, preventing catalyst corrosion during long-term operation. The HER performance of the Ru@Co2P/CNFs catalysts remained stable even after 40 h of continuous operation, demonstrating their long-lasting stability. This research introduces a new approach to developing cost-effective and highly active self-supported network-structured phosphide catalysts.

Precisely anchoring Ni-doped cobalt phosphide nanoparticles on phosphatized carbon nitride for efficient photocatalytic water splitting

Photocatalytic water splitting into hydrogen (H2) fuel or hydrogen peroxide (H2O2) chemicals has been considered as an ideal approach for converting solar energy into chemical energy. However, simultaneous production for these two valuable chemicals was always accompanied by the unsatisfactory catalytic productivity. Herein, we have employed the absorption-phosphidation strategy for precisely anchoring Ni-doped cobalt phosphide (CoP) nanoparticles (∼4 nm) on phosphatized carbon nitride (PCN) nanosheet. Without adding any sacrificial reagents, the photocatalyst exhibited excellent H2 evolution activities (248 μmol·g−1) and H2O2 generation (894 μmol·g−1) at 2 h, one of the highest activities among the previously reported carbon nitride-based catalysts. Comprehensive characterizations revealed that atomic-scale doped Ni element within CoP nanoparticles significantly accelerated surface catalytic reaction kinetics, which serve as the active centers for H2 and H2O2 evolution through reduction reaction. The PCN nanosheets with the increased electric conductivity and the decreased band gap energy could effectively promote photo-generated charge separation and transfer. Moreover, the Co-N coordination effect between PCN and Ni-doped CoP cocatalysts, could also accelerate the interfacial electron transfer. Synergizing the PCN nanosheet and intimately anchored Ni-CoP nanoparticles remarkably promoted the photocatalytic productivity and stability for simultaneous H2 and H2O2 production.

Cobalt Phosphide Nanoparticles Synthesized by Solvothermal Phosphidization of Metal-Organic Frameworks for Electrocatalytic Oxygen Evolution

Active and stable electrocatalysts for oxygen evolution reaction (OER) are crucial in the widespread application of water electrolyzers. Cobalt phosphide nanoparticles (Co-P) with different degrees of crystallinity are synthesized via solvothermal phosphidization of Co metal-organic frameworks and P4 using different solvents. The Co-P can be converted to active OER electrocatalysts in 1 M KOH, with the most active reaching 10 mA cm-2 OER current densities at 270 mV overpotential. The OER intermediate adsorption energy is tuned by the electron interactions in the crystalline/amorphous heterostructured Co-P, which show the highest intrinsic OER activity. After the long-term OER in base, surface phosphides are converted to (oxy)hydroxides that are the active species towards OER.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure by plasma for lithium and sodium storage.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure are synthesized using Ar-H2-P plasma. In situ phosphorization and graphene reduction are achieved at the same time. Benefitting from the sandwich structure and heterointerface between CoP and RGO, the electrode delivered a high reversible capacity and durable lifespan for both lithium and sodium storage.

In-situ formation of cobalt phosphide nanoparticles confined in three-dimensional porous carbon for high-performing zinc-air battery and water splitting

AbstractThe rational design of efficient and stable carbon-based electrocatalysts for oxygen reduction and oxygen evolution reactions is crucial for improving energy density and long-term stability of rechargeable zinc-air batteries (ZABs). Herein, a general and controllable synthesis method was developed to prepare three-dimensional (3D) porous carbon composites embedded with diverse metal phosphide nanocrystallites by interfacial coordination of transition metal ions with phytic acid-doped polyaniline networks and subsequent pyrolysis. Phytic acid as the dopant of polyaniline provides favorable anchoring sites for metal ions owing to the coordination interaction. Specifically, adjusting the concentration of adsorbed cobalt ions can achieve the phase regulation of transition metal phosphides. Thus, with abundant cobalt phosphide nanoparticles and nitrogen- and phosphorus-doping sites, the obtained carbon-based electrocatalysts exhibited efficient electrocatalytic activities toward oxygen reduction and evolution reactions. Consequently, the fabricated ZABs exhibited a high energy density, high power density of 368 mW cm−2, and good cycling/mechanical stability, which could power water splitting for integrated device fabrication with high gas yields.

Confinement of CoOx-CoP nanoparticles inside nitrogen doped CNTs: A low-cost ORR electrocatalyst

Non-noble metal containing catalysts for oxygen reduction reaction (ORR) are being targeted due to their low cost and availability. The rarity, high-cost, and self-poisoning of noble metals are the main drawbacks for the large-scale applications. Herein, a facile and simple synthetic strategy is adopted to prepare non-noble metal-based nitrogen doped carbon nanotubes (N-CNTs). The cobalt oxides (CoOx) nanoparticles are in-situ encapsulated inside these N-CNTs which are then treated with acid (HCl) and phosphidized to obtain CoOx-CoP/N-CNTs. High resolution transmission electron spectroscopy (HR-TEM) results reveal that the ends of N-CNTs are closed with nanoparticles. X-ray photoelectron spectroscopy (XPS) confirms the presence of cobalt oxide and cobalt phosphide nanoparticles. The catalyst CoOx-CoP/N-CNTs2 demonstrated Eonset and E1/2 of 0.96 V and 0.81 V, respectively in alkaline environment which is very much comparable to the state of art catalyst (20 wt% Pt/C). Acid treatment significantly enhances the electrocatalytic activity for ORR in comparison to material synthesized without prior treatment with acid. The catalyst exhibits excellent durability over 10,000 cycles and methanol tolerance to 0.5 M methanol addition. The enhanced ORR activity is attributed to synergistic effect of carbon matrix and encapsulated nanoparticles.

Electrospun porous carbon nanofibers decorated with iron-doped cobalt phosphide nanoparticles for hydrogen evolution

Developing highly active and cost-effective electrocatalysts to replace noble metal catalysts is the main route for the efficient production of green hydrogen. Herein, we have successfully fabricated iron-doped cobalt phosphide nanoparticles-decorated porous carbon nanofibers (Fe-CoP/PCNF) by a facile three-step method. On one hand, the electrospun nanofibers could serve as porous and conductive substrate for the exposure of active sites and the fast charge transfer; On the other hand, the Fe-CoP nanoparticles with optimized hydrogen adsorption free energy showed high intrinsic catalytic activity. Hence, the Fe-CoP/PCNF achieves excellent HER performance, which affords overpotential of 151 mV to support the current density of 10 mA cm −2 in acid media. Moreover, the nanoparticles were protected by a carbon layer, preventing the electrocatalyst from corrosion during long-term operation. The findings may shed light on the rational exploration of nanofibrous electrocatalysts for highly efficient hydrogen evolution. • Fe-doped CoP nanoparticles are conveniently generated on electrospun porous carbon nanofiber. • The Fe-doped CoP nanoparticles possess high intrinsic catalytic activity for HER. • Porous carbon nanofibers with massive active sites and high conductivity are beneficial to the HER performance.

Dual-functional cobalt phosphide nanoparticles for performance enhancement of lithium-sulfur battery

Dual-functional cobalt phosphide nanoparticles for performance enhancement of lithium-sulfur battery