Metal Phosphides Research Articles

Catalytic Applications in the Production of Hydrotreated Vegetable Oil (HVO) as a Renewable Fuel: A Review

The significance and challenges of hydrotreatment processes for vegetable oils have recently become apparent, encompassing various reactions like decarbonylation, decarboxylation, and hydrogenation. Heterogeneous noble or transition metal catalysts play a crucial role in these reactions, offering high selectivity in removing oxygen and yielding desired hydrocarbons. Notably, both sulphided and non-sulphided catalysts exhibit effectiveness, with the latter gaining attention due to health and toxicity concerns associated with sulphiding agents. Nickel-based catalysts, such as NiP and NiC, demonstrate specific properties and tendencies in deoxygenation reactions, while palladium supported on activated carbon catalysts shows superior activity in hydrodeoxygenation. Comparisons between the performances of different catalysts in various hydrotreatment processes underscore the need for tailored approaches. Transition metal phosphides (TMP) emerge as promising catalysts due to their cost-effectiveness and environmental friendliness. Ultimately, there is an ongoing pursuit of efficient catalysts and the importance of further advancements in catalysis for the future of vegetable oil hydrotreatment.

Vacancies-Induced Delocalized States Cobalt Phosphide for Binder-Free Anode Toward Stable and High-Rate Sodium-Ion Batteries.

Metal phosphides with easy synthesis, controllable morphology, and high capacity are considered as potential anodes for sodium-ion batteries (SIBs). However, the inherent shortcomings of metal phosphating materials, such as conductivity, kinetics, volume strain, etc are not satisfactory, which hinders their large-scale application. Here, a CoP@carbon nanofibers-composite containing rich Co─N─C heterointerface and phosphorus vacancies grown on carbon cloth (CoP1-x@MEC) is synthesized as SIB anode to accomplish extraordinary capacity and ultra-long cycle life. The hybrid composite nanoreactor effectively impregnates defective CoP as active reaction center while offering Co─N─C layer to buffer the volume expansion during charge-discharge process. These vast active interfaces, favored electrolyte infiltration, and a well-structured ion-electron transport network synergistically improve Na+ storage and electrode kinetics. By virtue of these superiorities, CoP1-x@MEC binder-free anode delivers superb SIBs performance including a high areal capacity (2.47 mAh cm-2@0.2mA cm-2), high rate capability (0.443 mAh cm-2@6mA cm-2), and long cycling stability (300 cycles without decay), thus holding great promise for inexpensive binder-free anode-based SIBs for practical applications.

Electronic modulation on allotropic Co2P/CoP heterojunctions with N, P co-doped porous carbon matrix through metal-injection toward high-efficiency water splitting

The interfacial electron modulation of electrocatalysts is a useful technique for promoting catalyst performance for the water-related dissociation reactions. Herein, a high-efficient Fe-doped allotropic Co2P/CoP heterojunction nanoparticles embedded in N, P co-doped carbon matrix was constructed. The intense electrical interfacial contacts between the allotropic heterojunction optimized the reaction kinetics by boosting efficient charged active centers, regulating the intermediate adsorption/desorption. The incorporation of Fe atoms further enhancing the heterointerface contact between CoP and Co2P by providing favorable electronic properties and special coordination environment, causing the interfacial coupling enhancement. Therefore, Fe-Co2P/CoP possesses outstanding performance in both hydrogen evolution reaction and oxygen evolution reaction, with small overpotentials of 174 mV and 286 mV at 10 mA·cm−2 in alkaline medium, respectively. And only 1.71 V battery voltage is needed for the Fe-Co2P/CoP (+, −) cell device with satisfactory durability. This finding provides valuable insights into the engineering of electronic structures of well-designed metal phosphides for water electrolysis.

Structure- and Morphology-Controlled Synthesis of Hexagonal Ni2-x Zn x P Nanocrystals and Their Composition-Dependent Electrocatalytic Activity for Hydrogen Evolution Reaction.

Nickel phosphides are an emerging class of earth-abundant catalysts for hydrogen generation through water electrolysis. However, the hydrogen evolution reaction (HER) activity of Ni2P is lower than that of benchmark Pt group catalysts. To address this limitation, an integrated theoretical and experimental study was performed to enhance the HER activity and stability of hexagonal Ni2P through doping with synergistic transition metals. Among the nine dopants computationally studied, zinc emerged as an ideal candidate due to its ability to modulate the hydrogen binding free energy (ΔG H) closer to a thermoneutral value. Consequently, phase pure hexagonal Ni2-x Zn x P nanocrystals (NCs) with a solid spherical morphology, variable compositions (x = 0-17.14%), and size in the range of 6.8 ± 1.1-9.1 ± 1.1 nm were colloidally synthesized to investigate the HER activity and stability in alkaline electrolytes. As predicted, the HER performance was observed to be composition-dependent with Zn compositions (x) of 0.03, 0.07, and 0.15 demonstrating superior activity with overpotentials (η-10) of 188.67, 170.01, and 135.35 mV, respectively at a current density of -10 mA/cm2, in comparison to Ni2P NCs (216.2 ± 4.4 mV). Conversely, Ni2-x Zn x P NCs with x = 0.01, 0.38, 0.44, and 0.50 compositions showed a notable decrease in HER activity, with corresponding η-10 of 225.3 ± 3.2, 269.9 ± 4.3, 276.4 ± 3.7 and 263.9 ± 4.9 mV, respectively. The highest HER active catalyst was determined to be Ni1.85Zn0.15P NCs, featuring a Zn concentration of 5.24%, consistent with composition-dependent ΔG H calculations. The highest performing Ni1.85Zn0.15P NCs displayed a Heyrovsky HER mechanism, enhanced kinetics and electrochemically active surface area (ECSA), and superior corrosion tolerance with a negligible increase of η-10 after 10 h of continuous HER. This study provides critical insights into enhancing the performance of metal phosphides through doping-induced electronic structure variation, paving the way for the design of high-efficiency and durable nanostructures for heterogeneous catalytic studies.

Electronic transfer and structural reconstruction in porous NF/FeNiP-CoP@NC heterostructure for robust overall water splitting in alkaline electrolytes

Multimetal phosphides derived from metal-organic frameworks (MOFs) have garnered significant interest owing to their distinct electronic configurations and abundant active sites. However, developing robust and efficient catalysts based on metal phosphides for overall water splitting (OWS) remains challenging. Herein, we present an approach for synthesizing a self-supporting hollow porous cubic FeNiP-CoP@NC catalyst on a nickel foam (NF) substrate. Through ion exchange, the reconstruction chemistry transforms the FeNi-MOF nanospheres into intricate hollow porous FeNi-MOF-Co nanocubes. After phosphorization, numerous N, P co-doped carbon-coated FeNiP-CoP nanoparticles were tightly embedded within a two-dimensional (2D) carbon matrix. The NF/FeNiP-CoP@NC heterostructure retained a porous configuration, numerous heterogeneous interfaces, distinct defects, and a rich composition of active sites. Moreover, incorporating Co and the resulting structural evolution facilitated the electron transfer in FeNiP-CoP@NC, enhancing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) processes. Consequently, the NF/FeNiP-CoP@NC catalyst demonstrated very low overpotentials of 78 mV for OER and 254 mV for HER in an alkaline medium. It also exhibited excellent long-term stability at various potentials (@10 mA cm−2, @20 mA cm−2, and @50 mA cm−2). As an overall water splitting cell, it required only 1.478 V to drive a current density of 50 mA cm−2 and demonstrated long-term stability. Density functional theory (DFT) calculations revealed a synergistic effect between multimetal phosphides, enhancing the intrinsic OER and HER activities of FeNiP-CoP@NC. This work not only elucidates the role of heteroatom induction in structural reconstruction but also highlights the importance of electronic structure modulation.

Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation

AbstractMetal phosphides have been hailed as potential replacements for scarce noble metal catalysts in many aspects of the hydrogen economy from hydrogen evolution to selective hydrogenation reactions. But the need for dangerous and costly phosphorus precursors, limited support dispersion, and low stability of the metal phosphide surface toward oxidation substantially lower the appeal and performance of metal phosphides in catalysis. We show here that a 1‐step procedure that relies on safe and cheap precursors can furnish an air‐stable Ni2P/Al2O3 catalyst containing 3.2 nm nanoparticles. Ni2P/Al2O3 1‐step is kinetically competitive with the palladium‐based Lindlar catalyst in selective hydrogenation catalysis, and a loading corresponding to 4 ppm Ni was sufficient to convert 0.1 mol alkyne. The 1‐step synthetic procedure alters the surface ligand speciation of Ni2P/Al2O3, which protects the nanoparticle surface from oxidation, and ensures that 85 % of the initial catalytic activity was retained after the catalyst was stored under air for 1.5 years. Preparation of Ni2P on a variety of supports (silica, TiO2, SBA‐15, ZrO2, C and HAP) as well as Co2P/Al2O3, Co2P/TiO2 and bimetallic NiCoP/TiO2 demonstrates the generality with which supported metal phosphides can be accessed in a safe and straightforward fashion with small sizes and high dispersion.

Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation.

Metal phosphides have been hailed as potential replacements for scarce noble metal catalysts in many aspects of the hydrogen economy from hydrogen evolution to selective hydrogenation reactions. But the need for dangerous and costly phosphorus precursors, limited support dispersion, and low stability of the metal phosphide surface toward oxidation substantially lower the appeal and performance of metal phosphides in catalysis. We show here that a 1-step procedure that relies on safe and cheap precursors can furnish an air-stable Ni2P/Al2O3 catalyst containing 3.2 nm nanoparticles. Ni2P/Al2O3 1-step is kinetically competitive with the palladium-based Lindlar catalyst in selective hydrogenation catalysis, and a loading corresponding to 4 ppm Ni was sufficient to convert 0.1 mol alkyne. The 1-step synthetic procedure alters the surface ligand speciation of Ni2P/Al2O3, which protects the nanoparticle surface from oxidation, and ensures that 85 % of the initial catalytic activity was retained after the catalyst was stored under air for 1.5 years. Preparation of Ni2P on a variety of supports (silica, TiO2, SBA-15, ZrO2, C and HAP) as well as Co2P/Al2O3, Co2P/TiO2 and bimetallic NiCoP/TiO2 demonstrates the generality with which supported metal phosphides can be accessed in a safe and straightforward fashion with small sizes and high dispersion.

Assessment of the Role of Keratin 18 and High Mobility Group Box 1 Biomarkers for Early Prediction of Drugs and Chemicals Induced Hepatotoxicity A Prospective Study in the Poison Control Center of Ain Shams University Hospitals (PCC-ASUH)

Abstract Background Drug-induced hepatotoxicity represents a major clinical problem worldwide. Hepatotoxicity may be caused by drugs, chemicals used in laboratories and industries or natural products and rodenticides such as metal phosphides. Early identification of hepatotoxicity would facilitate patient- individualized treatment strategies. New biomarkers (HMGB1and K18) used to identify subsequent acute liver injury (ALI) in patients on admission to the hospital. Objectives This study aims to assess the role of keratin 18 and high mobility group box 1 biomarkers in early prediction of drugs and chemicals induced hepatotoxicity for better outcome and to compare these new liver biomarkers with the currently used parameters (ALT & AST) in the early prediction of drugs and chemicals induced hepatotoxicity. Methods This prospective study was conducted on 50 adult patients of both sex presented to the PCC- ASUH with acute intoxication of hepatotoxic drugs or chemicals. For all patients, we measured high mobility group box-1 (HMGB1), keratin-18 (K18), AST and ALT on admission then patients were followed- up for development of liver injury . Subjects were classified into group I (control group), group II (no liver affection) and group III (with liver affection). Receiver operator characteristic (ROC) curve was used to compare sensitivity and specificity to report liver injury versus alanine transaminase (ALT) and aspartate transaminase (AST). Results This study showed that HMGB1 and K18 were much more elevated in patients who developed liver injury in the first hospital presentation when ALT and AST were within normal ranges with a highly significant difference between the hepatotoxic and non-hepatotoxic group. ROC analysis showed that HMGB1 and K18 were more sensitive than ALT and AST and more specific than AST in predicting ALI. Conclusion Elevations in plasma HMGB1, and K18 identified subsequent ALI development in patients on admission to the hospital, soon after drug and chemical overdose, and in patients with ALT and AST in the normal range.

Titelbild: Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation (Angew. Chem. 33/2024)

Titelbild: Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation (Angew. Chem. 33/2024)

Cover Picture: Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation (Angew. Chem. Int. Ed. 33/2024)

Cover Picture: Expedited Synthesis of Metal Phosphides Maximizes Dispersion, Air Stability, and Catalytic Performance in Selective Hydrogenation (Angew. Chem. Int. Ed. 33/2024)

Facile Carbothermal Synthesis of Metal Phosphides-Based Multifunctional Electrocatalysts via Polyaniline Doped with Phosphoric Acid

Transition metal phosphides (TMPs) and their composites are promising non-platinum electrocatalysts for hydrogen evolution (HER), oxygen evolution (OER), and oxygen reduction (ORR) reactions. But traditional methods to obtain these electrocatalysts are usually multi-step and include the participation of hazardous phosphorus compounds during phosphidation. Here, the possibility of using a polyaniline doped with phosphoric acid (PANI∙H3PO4)—as a source of C, N and P simultaneously - to obtain composites based on N,P-doped carbon and nano- and/or submicron TMP particles as HER, OER and ORR electrocatalysts is demonstrated. The pyrolysis of PANI∙H3PO4 together with Co, Ni, Mo, or Fe salt allows the formation of such composite electrocatalysts by the carbon thermal reduction route. Regardless of the pH of the electrolyte, the MoP-based electrocatalyst is characterized in HER by the smallest Tafel slope and overpotential of hydrogen evolution and also exhibits high stability during long-term operation. At the same time, other composites are multifunctional electrocatalysts possessing activity not only in HER, but also in OER and ORR. The proposed approach can be a starting point for a simple, universal in choice of d-metal, and environmentally attractive preparation of multifunctional TMP-based electrocatalysts with further improvement of their performance.

Metal phosphide poisoning in a disaster-stricken area. Can early hemodialysis improve outcomes?

Phosphide metal poisoning results in tens of thousands of fatalities per year worldwide. The mortality in critically ill patients often exceeds 50%. The available treatment is supportive and there is no antidote. Dialysis is recommended to treat advanced complications but has not been prescribed early in the process. In this study we report our experience in using dialysis in the early hours of presentation of the patients and suggest it can favorably improve the prognosis. We also draw attention to the risk of suicide under conditions of chronic conflict such as those in northwestern Syria, and to the lack of necessary mental health support for patients after suicide attempts. Retrospective review of records of patients poisoned with aluminum phosphide and admitted to critical care facilities in northwestern Syria between July 2022 and June 2023. During the observation period 16 cases were encountered. Suicide was the reason of the poisoning in 15 patients, the median patient age was 18 years and over two thirds of the patients were female. Early dialysis was used in 11 patients who were critically ill and their mortality rate was 18%. Phosphide metal poisoning is common in the disasters stricken area of northwestern Syria. Most cases are suicidal and impact young females. Early dialytic interventions may favorably impact the outcomes.

Interface Engineering Induced N, P-Doped Carbon-Shell-Encapsulated FeP/NiP2/Ni5P4/NiP Nanoparticles for Highly Efficient Hydrogen Evolution Reaction

Modifying the electronic structure of a catalyst through interface engineering is an effective strategy to enhance its activity in the hydrogen evolution reaction (HER). Interface engineering is a viable strategy to enhance the catalytic activity of transition metal phosphides (TMPs) in the HER process. The interface-engineered FeP/NiP2/Ni5P4/NiP multi-metallic phosphide nanoparticles confined in a N, P-doped carbon matrix was developed by a simple one-step low-temperature phosphorization treatment, which only requires 72 and 155 mV to receive the current density of 10 mA/cm2 in acid and alkaline electrolyte, respectively. This enhanced performance can be primarily attributed to the heterointerface of FeP/NiP2/Ni5P4/NiP multi-metallic phosphides, which promotes electron redistribution and optimizes the adsorption/desorption strength of H* on the active sites. Furthermore, the N, P-doped carbon framework that encapsulates the nanoparticles inhibits their aggregation, leading to an increased availability of active sites throughout the reaction. The results of this study open up a straightforward and innovative approach to developing high-performance catalysts for hydrogen production.

Revealing Structural Evolution of Nickel Phosphide-Iron Oxide Core-Shell Nanocatalysts in Alkaline Medium for the Oxygen Evolution Reaction.

Metal phosphide-containing materials have emerged as a potential candidate of nonprecious metal-based catalysts for alkaline oxygen evolution reaction (OER). While it is known that metal phosphide undergoes structural evolution, considerable debate persists regarding the effects of dynamics on the surface activation and morphological stability of the catalysts. In this study, we synthesize NiP x -FeO x core-shell nanocatalysts with an amorphous NiP x core designed for enhanced OER activity. Using ex situ X-ray absorption spectroscopy, we elucidate the local structural changes as a function of the cyclic voltammetry cycles. Our studies suggest that the presence of corner-sharing octahedra in the FeO x shell improves structural rigidity through interlayer cross-linking, thereby inhibiting the diffusion of OH-/H2O. Thus, the FeO x shell preserves the amorphous NiP x core from rapid oxidation to Ni3(PO4)2 and Ni(OH)2. On the other hand, the incorporation of Ni from the core into the FeO x shell facilitates absorption of hydroxide ions for OER. As a result, Ni/Fe(OH) x at the surface oxidizes to the active γ-(oxy)hydroxide phase under the applied potentials, promoting OER. This intriguing synergistic behavior holds significance as such a synthetic route involving the FeO x shell can be extended to other systems, enabling manipulation of surface adsorption and diffusion of hydroxide ions. These findings also demonstrate that nanomaterials with core-shell morphologies can be tuned to leverage the strength of each metallic component for improved electrochemical activities.

Controlled synthesis of nickel phosphides: Mechanistic insights and catalytic activity in hydrogen peroxide production

Strategically designing oxygen reduction reaction (ORR) electrocatalysts based on electronic structure is a pivotal method for enhancing the electrocatalytic activity and selectivity of two-electron (2e) reactions. While many transition metal phosphides, including NixPy, have demonstrated activity in electrocatalytic reactions, their effectiveness in 2e ORR electrocatalysis is still uncertain. In this study, guided by the theoretical insights into high electroactivity unveiled by the d-band center (Ed) theory, we engineered and synthesized Ni2P/Ni5P4 nanosheets (NSs). Functioning as 2e ORR electrocatalysts in alkaline environments, the Ni2P/Ni5P4 NSs exhibited outstanding 2e selectivity of up to 95%, with an electron transfer number close to two. Demonstrating a Faradaic efficiency exceeding 95% over a wide potential range (0.2–0.5 V), these NSs displayed extended stability for over 48 h, outperforming most transition metal-based catalysts reported in literature. By employing density functional theory (DFT) calculations, the increased activity is ascribed to the adjustment of the d-band center at the engineered heterostructure interface, effectively regulating the adsorption energy of oxygen-containing intermediates (*OOH). This study offers crucial insights into the methodical design and production of effective transition metal phosphide electrocatalysts guided by the d-band center theory.

Capillary-driven microchip integrated with nickel phosphide hybrid-modified electrode for the electrochemical detection of glucose

BackgroundTransition metal phosphides with properties similar to platinum metal have received increasing attention for the non-enzymatic detection of glucose. However, the requirement of highly corrosive reagent during sample pretreatment would impose a potential risk to the human body, limiting their practical applications. ResultsIn this study, we report a self-powered microfluidic device for the non-enzymatic detection of glucose using nickel phosphide (Ni2P) hybrid as the catalyst. The Ni2P hybrid is synthesized by pyrolysis of metal-organic framework (MOF)-based precursor and in-situ phosphating process, showing two linear detection ranges (1 μM–1 mM, 1 mM–6 mM) toward glucose with the detection limit of 0.32 μM. The good performance of Ni2P hybrid for glucose is attributed to the synergistic effect of Ni2P active sites and N-doped porous carbon matrix. The microchip is integrated with a NaOH-loaded paper pad and a capillary-based micropump, enabling the automatic NaOH redissolution and delivery of sample solution into the detection chamber. Under the optimized condition, the Ni2P hybrid-based microchip realized the detection of glucose in a user-friendly way. Besides, the feasibility of using this microchip for glucose detection in real serum samples has also been validated. SignificanceThis article presents a facile fabrication method utilizing a MOF template to synthesize a Ni2P hybrid catalyst. By leveraging the synergy between the Ni2P active sites and the N-doped carbon matrix, an exceptional electrochemical detection performance for glucose has been achieved. Additionally, a self-powered chip device has been developed for convenient glucose detection based on the pre-established high pH environment on the chip.

Two-Dimensional Transition Metal Phosphides As Cathode Additive in Robust Lithium-Sulfur Batteries.

The development of advanced cathode materials able to promote the sluggish redox kinetics of polysulfides is crucial to bringing lithium-sulfur batteries to the market. Herein, two electrode materials: namely, Zr2PS2 and Zr2PTe2, are identified through screening several hundred thousand compositions in the Inorganic Crystal Structure Database. First-principles calculations are performed on these two materials. These structures are similar to that of the classical MXenes. Concurrently, calculations show that Zr2PS2 and Zr2PTe2 possess high electrical conductivity, promote Li ion diffusion, and have excellent electrocatalytic activity for the Li-S reaction and particularly for the Li2S decomposition. Besides, the mechanisms behind the excellent predicted performance of Zr2PS2 and Zr2PTe2 are elucidated through electron localization function, charge density difference, and localized orbital locator. This work not only identifies two candidate sulfur cathode additives but may also serve as a reference for the identification of additional electrode materials in new generations of batteries, particularly in sulfur cathodes.

Double loading of nickel phosphide surface for efficient hydrogen evolution reaction

Metal phosphide, as a highly conductive, chemically stable catalyst material, modulating its hydrogen adsorption is crucial to enhance hydrogen evolution reaction (HER) activity. In this study, we propose a double loading strategy to build Ag and AgP2 heterogeneous structures on Ni2P nanosheets (Ag-AgP2/Ni2P). This is the first application of AgP2 materials in HER. This innovative synthesis was achieved by liquid-phase adsorption of precursors and heat-treatment phosphorization, surface adsorbed AgNO3 is converted to Ag-AgP2 double loading at the same time as Ni2P formation. Density functional theory (DFT) calculations reveal that the double loading structure optimizes charge distribution and d-band center. Its hydrogen adsorption free energy is closer to electroneutrality than that of single loading and simple heterostructures. Benefiting from the special structure, Ag-AgP2/Ni2P exhibits excellent HER performance in alkaline media, requiring only 78 mV overpotential to reach 10 mA cm−2 and stability up to 200 h. This dual loading strategy broadens the perspective of heterogeneous electrocatalyst development.

Reactive P and S co-doped porous hollow nanotube arrays for high performance chloride ion storage

Developing stable, high-performance chloride-ion storage electrodes is essential for energy storage and water purification application. Herein, a P, S co-doped porous hollow nanotube array, with a free ion diffusion pathway and highly active adsorption sites, on carbon felt electrodes (CoNiPS@CF) is reported. Due to the porous hollow nanotube structure and synergistic effect of P, S co-doped, the CoNiPS@CF based capacitive deionization (CDI) system exhibits high desalination capacity (76.1 mgCl– g–1), fast desalination rate (6.33 mgCl– g–1 min–1) and good cycling stability (capacity retention rate of > 90%), which compares favorably to the state-of-the-art electrodes. The porous hollow nanotube structure enables fast ion diffusion kinetics due to the swift ion transport inside the electrode and the presence of a large number of reactive sites. The introduction of S element also reduces the passivation layer on the surface of CoNiP and lowers the adsorption energy for Cl– capture, thereby improving the electrode conductivity and surface electrochemical activity, and further accelerating the adsorption kinetics. Our results offer a powerful strategy to improve the reactivity and stability of transition metal phosphides for chloride capture, and to improve the efficiency of electrochemical dechlorination technologies.

Elucidating the mechanism on carbon nanotube-coated cobalt phosphide catalyst activating PMS to degrade norfloxacin contaminants

Transition metal phosphides have shown great potentials in persulfate activation for eliminating organic contaminants, while the understanding of the activation mechanism still remains fragmentary. Herein, a series of nitrogen-phosphorus-doped carbon nanotube-coated cobalt phosphide catalysts (Co/P-CNTs) were synthesized for activating peroxymonosulfate (PMS) to degrade norfloxacin (NOR). The optimal Co/P-CNTs-0.3 could eliminate NOR up to 97 % within 60 min in the presence of PMS. Results confirm that the synergistic interaction between multi-valent Co species in the Co/P-CNTs significantly contributes to the excellent PMS activation performance. The contribution of reactive oxygen species (ROS) to pollutant removal and the steady-state concentration of free radicals were quantitatively analyzed by means of chemical probe and reaction kinetics. A free radical mechanism dominated by SO4•– and NOR degradation pathway were identified, and the effect of coexisting inorganic anions was systematically evaluated. This study offers profound insights into the activation mechanism of metal phosphides towards environmental remediation.