Search Results (77)

Nickel phosphide catalysts (Ni₂P) were prepared using mesoporous molecular sieves as supports during isobaric co-impregnation. Ni₂P catalysts with different loading values were characterized, showing that the active phase on the surface of the catalysts was mainly Ni₂P and the catalysts still retained the mesoporous structural characteristics of the supports. The catalysts were evaluated using a 10 mL fixed-bed hydrogenation unit. The results showed that the nickel phosphide catalysts had a higher hydrogenation capacity than the sulfide catalysts and were able to preferentially hydrogenate and saturate most of the quinolines to decahydroquinolines, reduce the conversion of 1,2,3,4-tetrahydroquinoline to o-propylaniline, and reduce the inhibition of reactivity due to competitive adsorption. The effect of the catalyst on the path selectivity of quinoline hydrogenation was investigated, and the products of quinoline hydrogenation and denitrogenation consisted mainly of propylbenzene and propylcyclohexane, with propylcyclohexane accounting for 91.7% of the product and propylbenzene for 4.8%, under the conditions of nickel phosphide catalysts. Furthermore, the 25 wt% Ni₂P/SBA-15 catalyst exhibited no significant loss of catalytic activity during a 72 h stability evaluation conducted at 360 °C. Full article

Electrocatalytic urea oxidation reaction (UOR) is a promising dual-purpose approach for hydrogen production and wastewater treatment, addressing critical energy and environmental challenges. However, conventional anode materials often suffer from limited active sites and high charge transfer resistance, restricting UOR efficiency. To overcome these issues, a novel NiP@PNC/NF electrocatalyst was developed via a one-step thermal annealing process under nitrogen, integrating nickel phosphide (NiP) with phosphorus and nitrogen co-doped carbon nanotubes (PNCs) on a nickel foam (NF) substrate. This design enhances catalytic activity and charge transfer, achieving current densities of 50 mA cm⁻² at 1.34 V and 100 mA cm⁻² at 1.43 V versus the reversible hydrogen electrode (RHE). The electrode’s high electrochemical surface area (235 cm²) and double-layer capacitance (94.1 mF) reflect abundant active sites, far surpassing NiP/NF (48 cm², 15.8 mF) and PNC/NF (39.5 cm², 12.9 mF). It maintains exceptional stability, with only a 16.3% performance loss after 35 h, as confirmed by HR-TEM showing an intact nanostructure. Our single-step annealing technique provides simplicity, scalability, and efficient integration of NiP nanoparticles inside a PNC matrix on nickel foam. This method enables consistent distribution and robust substrate adhesion, which are difficult to attain with multi-step or more intricate techniques. Full article

Chlorpheniramine maleate (CPM) is a first-generation antihistamine that is frequently used to treat allergic reactions. However, excessive consumption presents potential health risks. Therefore, it is crucial to develop a quick and precise technique for identifying CPM levels. In this study, nickel cobalt phosphide (NiCoP), a binary metal phosphide, was successfully incorporated into carbon nanofibers. This involved creating a pore structure by adding polyvinylpyrrolidone (PVP) as a pore-forming template to a polyacrylonitrile (PAN) substrate via electrostatic spinning. An innovative electrochemiluminescent sensor for CPM detection was constructed using NiCoP/PVP/PAN carbon nanofibers (NiCoP/PVP/PAN/CNFs). Under optimal conditions, the electrochemical behavior of CPM was studied using NiCoP/PVP/PAN/CNF-modified working electrodes. These findings demonstrate that the three-dimensional porous network architecture of NiCoP/PVP/PAN/CNFs enhances the conductive properties of the material. Consequently, an electrochemical optical sensor fabricated using this structure exhibited remarkable performance. The linear detection range of the sensor was 1 × 10⁻⁸–7 × 10⁻⁵ mol/L, and the detection limit was 7.8 × 10⁻¹⁰ mol/L. When human urine and serum samples were examined, the sensor was found to have a high recovery rate (94.35–103.36%), which is promising for practical applications. Full article

Developing efficient bifunctional electrocatalysts with excellent stability at high current densities for overall water splitting is a challenging yet essential objective. However, transition metal phosphides encounter issues such as poor dispersibility, low specific surface area, and limited electronic conductivity, which hinder the achievement of satisfactory performance. Therefore, this study presents the highly efficient bifunctional electrocatalyst of CeO₂-modified NiFe phosphide on nickel foam (CeO₂/Ni₂P/Fe₂P/NF). Ni₂P/Fe₂P coupled with CeO₂ was deposited on nickel foam through hydrothermal synthesis and sequential calcination processes. The electrocatalytic performance of the catalyst was evaluated in an alkaline solution, and it exhibited an HER overpotential of 87 mV at the current density of 10 mA cm⁻² and an OER overpotential of 228 mV at the current density of 150 mA cm⁻². Furthermore, the catalyst demonstrated good stability, with a retention rate of 91.2% for the HER and 97.3% for the OER after 160 h of stability tests. The excellent electrochemical performance can be attributed to the following factors: (1) The interface between Ni₂P/Fe₂P and CeO₂ facilitates electron transfer and reactant adsorption, thereby improving catalytic activity. (2) The three-dimensional porous structure of nickel foam provides an ideal substrate for the uniform distribution of Ni₂P, Fe₂P, and CeO₂ nanoparticles, while its high conductivity facilitates electron transport. (3) The incorporation of larger Ce³⁺ ions in place of smaller Fe³⁺ ions leads to lattice distortion and an increase in defects within the NiFe-layered double hydroxide structure, significantly enhancing its catalytic performance. This research finding offers an effective strategy for the design and synthesis of low-cost, high-potential catalysts for water electrolysis. Full article

Nickel phosphides (Ni_xP_y) are recognized as promising alternatives to noble-metal catalysts for the oxygen evolution reaction (OER). NiP, consisting of the equal stoichiometric ratio of Ni and P, could help quantify the catalytic effect of P and Ni. In this work, density functional theory (DFT) is employed to investigate the OER mechanism on NiP surfaces. We found that P atoms help stabilize O* at the adsorption sites. The rich electron donation from the Ni atom can alter the local charge distribution and enhance the interaction between O* and P atoms. Both oxygen intermediate adsorption energy and OER overpotential exhibit linear correlations with the charge of adsorption sites. Electron loss at the site induces the overall system to exhibit Lewis acidic characteristics, facilitating the OER and leading to a substantial overpotential reduction of up to 0.61 V compared to Lewis basic structures. Leveraging electronic structure theory and Lewis acid–base theory, we offer a new insight into the OER mechanism on the NiP surface, demonstrating that the catalytic activity of bulk metallic surface materials like NiP can be optimized by tailoring the local surface chemical environment. Full article

The electrocatalytic reduction of nitrate (ERN) to ammonia offers a promising route to address energy shortages and environmental pollution, but its practical application is hindered by low selectivity due to complex eight-electron transfer pathways and high energy consumption (EC) from the kinetically sluggish oxygen evolution reaction (OER). This study proposes a dual strategy: (1) designing a multi-functional self-supported ANP electrode via vapor deposition to enhance ERN activity and (2) replacing the OER with thermodynamically favorable anodic reactions (urea oxidation reaction (UOR), sodium metabisulfite oxidation reaction (S(IV)OR), sulfite and urea oxidation reaction (S(IV)/UOR)) to reduce EC. The ANP cathode achieved a nitrate removal rate (R%) of 97.7%, ammonia selectivity (SE%) of 91.8%, and Faradaic efficiency (FE) of 97.3% at −1.2 V, with an ammonia yield of 0.0616 mmol h⁻¹ mg⁻¹ and an EC of 8.239 kWh/kg, while in situ-generated atomic hydrogen (*H) was identified as key to improving nitrate removal and selectivity. Replacing the OER with alternative anodic reactions significantly improved system efficiency: the UOR reduced EC by 17.5%, S(IV)OR saved 27.6% energy with 7.1% higher ammonia yield, and a hybrid S(IV)/UOR system achieved a 32.1% lower EC and a 12.6% greater ammonia yield than the OER. These differences stemmed from variations in cell voltage and ammonia production rates. This work provides a viable approach for selective nitrate-to-ammonia conversion and guides the design of energy-efficient electrocatalytic systems for sustainable nitrogen recovery. Full article

Developing sustainable and efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing energy storage technologies. This study explored the dual role of phosphorus as a dopant in carbon matrices and a key component in nickel phosphides (Ni₂P and Ni₁₂P₅), synthesized using dopamine (PDA) and ammonium phosphate as eco-friendly precursors. The phase formation of nickel phosphides was found to be highly dependent on the P/PDA ratio (0.15, 0.3, 0.6, and 0.9), allowing for the selective synthesis of Ni₂P or Ni₁₂P₅. Operando Raman spectroscopy revealed that both phases undergo surface transformation into nickel (oxy)hydroxide species under OER conditions, yet Ni₂P-based catalysts demonstrated superior activity and long-term stability. This enhancement is attributed to efficient electron transfer at the dynamic Ni₂P/NiOOH interface. Additionally, hollow nanostructures formed at intermediate P/PDA ratios (≤0.3) via the Kirkendall effect and Ostwald ripening contributed to an increased specific surface area and micropore volume, further improving the catalytic performance. Electrochemical impedance spectroscopy confirmed reduced interfacial resistance and enhanced charge transport. These findings offer new insights into the rational design of high-performance electrocatalysts and propose a green, tunable synthesis approach for advanced energy conversion applications. Full article

Transition metal phosphides (TMPs) show great potential as catalysts for the hydrogen evolution reaction (HER). FeP stands out as an efficient and cost-effective non-noble metal-based HER catalyst. However, FeP tends to aggregate and suffer from instability during the reaction. To tackle these challenges, we developed an efficient and straightforward approach to load metal-organic framework-derived N/P co-doped carbon-encapsulated FeP nanoparticles onto a nickel foam substrate (FeP@NPC/NF-450). This catalyst exhibits exceptional HER activity in 0.5 M H₂SO₄ and 1.0 M KOH solutions, with overpotentials of 68.3 mV and 106.1 mV at a current density of 10 mA cm⁻², respectively. Furthermore, it demonstrates excellent stability with negligible decay over 48 h in both acidic and alkaline solutions. The outstanding hydrogen evolution catalytic performance of FeP@NPC/NF-450 is mainly due to the N, P co-doped carbon matrix, which safeguards the FeP nanoparticles from aggregation and surface oxidation. Consequently, this enhances the availability of active sites during the hydrogen evolution reaction (HER), leading to improved stability. Moreover, introducing nickel foam offers a larger specific surface area and enhances charge transfer rates. This study provides a reference method for preparing stable and highly active electrocatalysts for hydrogen evolution. Full article

Introducing multiple active sites and constructing a heterostructure are efficient strategies to develop high-performance electrocatalysts. Herein, two-dimensional heterostructure NiFeP@FeOOH nanosheets supported by nickel foam (NF) are prepared by a hydrothermal–phosphorization–electrodeposition process. The synthesis of self-supporting heterostructure NiFeP@FeOOH nanosheets on NF increases the specific surface region, while bimetallic phosphide realizes rapid charge transfer, improving the electron transfer rate. The introduction of FeOOH and the construction of a heterostructure result in a synergistic effect among the components, and the surface-active sites are abundant. In situ Raman spectroscopy showed that the excellent oxygen evolution reaction (OER) performance was due to reconstruction-induced hydroxyl oxide, which achieved a multi-active site reaction. The NiFeP@FeOOH/NF electrocatalytic activity was then significantly improved. The findings indicate that in a 1.0 M KOH alkaline solution, NiFeP@FeOOH/NF showed an OER overpotential of 235 mV at 100 mA cm⁻², a Tafel slope of 46.46 mV dec⁻¹, and it worked stably at 50 mA cm⁻² for 80 h. This research proves that constructing heterostructure and introducing FeOOH are of great significance to the study of the properties of OER electrocatalysts. Full article

Tuning the chemical and structural environment of Ru-based nanomaterials is a major challenge for achieving active and stable hydrogen evolution reaction (HER) electrocatalysis. Here, we anchored ultrafine Ru nanoparticles (with a size of ~4.2 nm) on a hierarchical Ni₂P array (Ru/Ni₂P) to enable highly efficient HER. The Ni₂P promoter weakened the adsorption of proton on Ru sites by accepting electrons from Ru nanoparticles. Moreover, the hierarchical Ni₂P endowed Ru catalysts with a large surface area and stable open structure. Consequently, the as-fabricated Ru/Ni₂P electrode displayed a low overpotential of 57 and 164 mV at the HER current densities of 10 and 50 mA cm⁻², respectively, comparable to the state-of-the-art Pt catalysts. Moreover, the Ru/Ni₂P electrode can operate stably for 96 h at 50 mA cm⁻² without performance degradation. After pairing with a commercial RuO₂ anode, the Ru/Ni₂P anode catalyzed overall water splitting at 1.73 V with a current density of 10 mA cm⁻², which was 0.16 V lower than its commercial Ni counterpart. In situ Raman studies further revealed the optimized proton adsorption at the Ru-active sites on Ni₂P promoter, thus enhancing the electrocatalytic HER performance. Full article

The supported Ni-P catalysts (marked as s-Ni-P/Hβ(3) and s-Ni-P/Ce-β(3)) were prepared by an incipient wetness step-impregnation method, and characterized by XRD, N₂ physisorption, TEM, XPS, and NH₃-TPD. The catalytic hydrodeoxygenation (HDO) performance was assessed using phenol in water (5.0 wt%) or in decalin (1.0 wt%) as the feed. After the introduction of Ce, the conversion of phenol increased due to the high dispersity of the active site. However, compared to s-Ni-P/Hβ(3), the amount of total and strong acid sites of s-Ni-P/Ce-β(3) decreased, restraining the cycloisomerization of cyclohexane to form methyl-cyclopentane. Moreover, the kinetics of the APHDO and OPHDO of phenol catalyzed by s-Ni-P/Hβ(3) and s-Ni-P/Ce-β(3) were investigated. Full article

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. Full article

The application of electrochemical hydrogen evolution reaction (HER) for renewable energy conversion contributes to the ultimate goal of a zero-carbon emission society. Metal phosphides have been considered as promising HER catalysts in the alkaline environment, which, unfortunately, is still limited owing to the weak adsorption of H* and easy dissolution during operation. Herein, a bimetallic NiCoP-2/NF phosphide is constructed on nickel foam (NF), requiring rather low overpotentials of 150 mV and 169 mV to meet the current densities of 500 and 1000 mA cm⁻², respectively, and able to operate stably for 100 h without detectable activity decay. The excellent HER performance is obtained thanks to the synergetic catalytic effect between Ni and Co, among which Ni is introduced to enhance the intrinsic activity and Co increases the electrochemically active area. Meanwhile, the protection of the externally generated amorphous phosphorus oxide layer improves the stability of NiCoP/NF. An electrolyser using NiCoP-2/NF as both cathode and anode catalysts in an alkaline solution can produce hydrogen with low electric consumption (overpotential of 270 mV at 500 mA cm⁻²). Full article

Hydrogen, one of the most promising forms of new energy sources, due to its high energy density, low emissions, and potential to decarbonize various sectors, has attracted significant research attention. It is known that electrocatalytic hydrogen production is one of the most widely investigated research directions due to its high efficiency in the conversion of electricity to H₂ gas. However, given the limited reserves and high cost of precious metals, the search for non-precious metal-based catalysts has been widely explored, for example, transition metal phosphides, oxides, and sulfides. Despite this interest, a detailed survey unveils that the surface and internal structures of the alternative catalysts, including their surface reconstruction, composition, and electronic structure, are poorly studied. As a result, a disconnection in the structure–property relationship severely hinders the rational design of efficient and reliable non-precious metal-based catalysts. In this review, by focusing on Ni₅P₄, a bifunctional catalyst for water splitting, we systematically summarize the material motifs pertaining to the different synthetic methods, surface characteristics, and hydrolysis properties. It is believed that a cascaded correlation may provide insights toward understanding the fundamental catalytic mechanism and design of robust alternative catalysts for hydrogen production. Full article