Search Results (71)

We report the fabrication of CoFeP-Ni(OH)₂/nickel foam (NF) composite electrodes via a two-step strategy involving the hydrothermal synthesis of Ni(OH)₂ on nickel foam followed by the electrochemical deposition of CoFeP. The integration of the Ni(OH)₂ interlayer not only provides a structurally robust interface but also facilitates synergistic redox activity, thereby significantly boosting the pseudocapacitive behavior of the electrode. Comparative analysis with bare CoFeP/NF reveals that the presence of the Ni(OH)₂ layer contributes to enhanced charge transfer efficiency and an increased electroactive surface area. Among the samples prepared under varying deposition cycles, the optimized CoFeP-Ni(OH)₂/NF electrode exhibits a high areal capacitance of 4244 mF cm⁻² at 2 mA cm⁻². Furthermore, an asymmetric supercapacitor device assembled with CoFeP-Ni(OH)₂/NF as the positive electrode and activated carbon as the negative electrode delivers a maximum energy density of 0.19 mWh cm⁻² at a power density of 0.37 mW cm⁻² and excellent cycling stability, retaining 72% of its initial capacitance after 5000 cycles at a high current density of 8 mA cm⁻². Full article

To address mass transport limitations in carbon nanofiber membrane electrodes for overall water splitting, a self-supporting nitrogen-doped hollow carbon nanofiber membrane embedded with Co/Co₂P heterojunctions (Co/Co₂P-NCNFs-H) was fabricated via continuous coaxial electrospinning. The architecture features uniform hollow channels (200–250 nm diameter, 30–50 nm wall thickness) and a high specific surface area (254 m² g⁻¹), as confirmed by SEM, TEM, and BET analysis. The Co/Co₂P heterojunction was uniformly dispersed on nitrogen-doped hollow carbon nanofibers through electrospinning, leverages interfacial electronic synergy to accelerate charge transfer and optimize the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Electrochemical tests demonstrated exceptional catalytic activity, achieving current densities of 100 mA cm⁻² at ultralow overpotentials of 405.6 mV (OER) and 247.9 mV (HER) in 1.0 M KOH—surpassing most reported transition metal catalysts for both half-reactions. Moreover, the electrode exhibited robust long-term stability, maintaining performance for nearly 20 h at 0.6 V (vs. Ag/AgCl) (OER) and over 250 h at −1.5 V (vs. Ag/AgCl) (HER), attributed to the mechanical integrity of the hollow architecture and strong metal–carbon interactions. This work demonstrates that integrating hollow nanostructures (enhanced mass transport) and heterojunction engineering (optimized electronic configurations) creates a scalable strategy for designing efficient bifunctional catalysts, offering significant promise for sustainable hydrogen production via water electrolysis. Full article

Developing efficient and durable electrocatalysts for the alkaline hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production. Herein, we report a novel RuP₂/Mn₂P₂O₇ heterojunction anchored on a three-dimensional nitrogen and phosphorus co-doped porous carbon (RuP₂/Mn₂P₂O₇/NPC) framework as a high-performance HER catalyst, synthesized via a controlled pyrolysis–phosphidation strategy. The heterostructure achieves uniform dispersion of ultrafine RuP₂/Mn₂P₂O₇ heterojunctions with well-defined interfaces. Furthermore, phosphorus doping restructures the electronic configuration of Mn and Ru species at the RuP₂/Mn₂P₂O₇ heterointerface, enabling enhanced catalytic activity through the accelerated electron transfer and kinetics of the HER. This RuP₂/Mn₂P₂O₇/NPC catalyst exhibits exceptional HER activity with 1 M KOH, requiring only 69 mV of overpotential to deliver 10 mA·cm⁻² and displaying a small Tafel slope of 69 mV·dec⁻¹, rivaling commercial 20% Pt/C. Stability tests reveal negligible activity loss over 48 h, underscoring the robustness of the heterostructure. The RuP₂/Mn₂P₂O₇ heterojunction demonstrates markedly reduced overpotentials for the electrochemical HER process, highlighting its enhanced catalytic efficiency and improved cost-effectiveness compared to the conventional catalytic systems. This work establishes a strategy for designing a transition metal phosphide heterostructure through interfacial electronic modulation, offering broad implications for energy conversion technologies. Full article

In recent years, transition metal-based catalytic materials have garnered considerable attention, particularly those exhibiting high catalytic efficiency toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, a self-supporting ternary transition metal phosphide (CoFeNi_0.2P) with a hierarchical structure was synthesized using the Prussian blue analogue (PBA)/zeolitic imidazolate framework-L (ZIF-L) template. Benefiting from the hierarchical structure of the PBA/ZIF-L precursor and the electronic structure modulation induced by Ni doping, the resulting CoFeNi_0.2P demonstrates impressive bifunctional electrocatalytic activity. Specifically, in 1 M KOH electrolyte, the CoFeNi_0.2P catalyst requires an overpotential of only 88 mV to deliver 10 mA cm⁻² for the HER and 248 mV to achieve 50 mA cm⁻² for the OER. Moreover, it demonstrates satisfactory stability toward both the HER and OER. When integrated into a two-electrode electrolyzer, CoFeNi_0.2P enables a current density of 10 mA cm⁻² at a cell voltage of 1.59 V, maintaining robust performance for over 25 h. This study provides a feasible strategy for the rational design of hierarchical electrocatalysts for efficient overall water splitting. Full article

Hydrogen energy holds great promise for alleviating energy and environmental issues, with alkaline electrochemical water splitting being a key approach for hydrogen production. However, the high cost and limited availability of noble-metal catalysts hinder its widespread application. This study presents a novel method to fabricate a NiFeP-CoP/CF electrode. By growing CoOOH nanosheets on Co foam at low temperatures and filling the gaps between nanosheets with Ni and Fe phosphides, the prepared electrode exhibits outstanding electrocatalytic performance. For the oxygen evolution reaction (OER) in alkaline media, it requires overpotentials of only 235 mV and 290 mV to reach current densities of 10 mA cm⁻² and 100 mA cm⁻², respectively. In the case of the hydrogen evolution reaction (HER), overpotentials of 89 mV and 172 mV are needed to achieve current densities of −10 mA cm⁻² and −100 mA cm⁻². The NiFeP-CoP/CF-based electrolytic cell requires a cell voltage of only 1.70 V to achieve a current density of 100 mA cm⁻² for overall water splitting. Moreover, during long-term continuous operation at 100 mA cm⁻², the overpotential for OER remains constant while that for HER decreases. The low-temperature growth of CoOOH nanosheets on Co foam provides a new strategy for large-scale electrode production applicable in electrochemical processes and pollutant degradation. Significantly, filling the nanosheet gaps with phosphides effectively enhances the electrocatalytic performance of the system. This work offers a facile and cost-effective technique for the large-scale production of metallic (oxyhydr)hydroxides for electrocatalytic water splitting, showing great potential for industrial 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

Fe₂P (iron phosphide) alloys have garnered significant interest in recent years due to their potential applications in permanent magnet materials, particularly in the context of energy-efficient and environmentally friendly technologies. We have sought to tailor the magnetic properties, such as magnetization, coercivity, and Curie temperature, to meet the specific requirements of rare-earth-free permanent magnets for various industrial sectors. In this work, we review recent advancements in the exploration of substitutions (Si, Co, Mn, and Ni) within $\mathrm{F}{\mathrm{e}}_2\mathrm{P}$ alloys aimed at enhancing their magnetic performance as candidates for permanent magnets. The X-ray patterns of (Fe,Co)₂P show great crystallinity with a pure Fe₂P phase even with Mn and Ni substitutions. The Fe₂P structure crystallizes in the P-62m space group. It has been confirmed that the transition metals substitute the 3g Fe-site, sometimes with adverse effects regarding magnetic properties with Co vs. Ni substitution, and that Si substitutes the 2c P-site. The saturation magnetization increases ($M_S=87\mathrm{A}{\mathrm{m}}^2/\mathrm{k}\mathrm{g}$) with Mn substitution, while the Curie temperature decreases with these substitutions. The impact of various substitutional elements on the magnetic properties of $\mathrm{F}{\mathrm{e}}_2\mathrm{P}$ alloys is highlighted, and challenges encountered in this field are reported. Full article

Iron phosphide (FeP) represents a promising anode material for sodium-ion batteries, attributed to its significant theoretical capacity, moderate operating potential, and natural abundance. However, due to the low conductivity and significant volume expansion of FeP electrodes, their specific capacity and cycle life decrease rapidly during charging and discharging. In this study, we synthesized FeP nanoparticles supported on a three-dimensional porous carbon framework composite (FeP@PCF) using a straightforward colloidal blow molding method, employing iron nitrate nonahydrate and polyvinylpyrrolidone as raw materials. The nanoscale size of the FeP particles, along with the abundant mesopores and high specific surface area of the 3D porous carbon framework, contribute to the impressive sodium storage performance of FeP@PCF. It is revealed that FeP@PCF achieves a remarkable capacity of 196.6 mA h g⁻¹ at a current density of 1.0 A g⁻¹. Furthermore, after 800 cycles at this current density, it retains a capacity of 172.4 mA h g⁻¹, demonstrating excellent cycling performance. Kinetic and dynamic studies indicate that this exceptional performance is largely attributed to the well-designed FeP@PCF, which exhibits a high capacitive contribution of 88.3% at a scan rate of 1 mV s⁻¹. Full article

Hydrogen is regarded as an ideal energy carrier to cope with the energy crisis and environmental problems due to its high energy density, cleanliness, and renewability. Although there are several primary methods of industrial hydrogen production, hydrogen evolution reaction (HER) is an efficient, eco-friendly, and sustainably green method for the preparation of hydrogen which has attracted considerable attention. However, this technique is characterized by slow reaction kinetics and high energy potential owing to lack of electrocatalysts with cost-effective and high performance which impedes its scale-up. To address this issue, various studies have focused on electrospun micro/nanofiber-based electrocatalysts for HER due to their excellent electron and mass transport, high specific surface area, as well as high porosity and flexibility. To further advance their development, recent progress of highly efficient HER electrospun electrocatalysts is reviewed. Initially, the characteristics of potential high-performance electrocatalysts for HER are elucidated. Subsequently, the advantages of utilizing electrospinning technology for the preparation of electrocatalysts are summarized. Then, the classification of electrospun micro/nanofiber-based electrocatalysts for HER are analyzed, including metal-based electrospun electrocatalyst (noble metals and alloys, transition metals, and alloys), metal–non-metal electrocatalysts (metal sulfide-based electrocatalysts, metal oxide-based electrocatalysts, metal phosphide-based electrocatalysts, metal nitride-based electrocatalysts, and metal carbide-based electrocatalysts), metal-free electrospun micro/nanofiber-based electrocatalysts, and hybrid electrospun micro/nanofiber-based electrocatalysts. Following this, enhancement strategies for electrospun micro/nanofiber-based electrocatalysts are discussed. Finally, current challenges and the future research directions of electrospun micro/nanofiber-based electrocatalysts for HER are concluded. 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

Defect engineering, by adjusting the surface charge and active sites of CoP catalysts, significantly enhances the efficiency of the oxygen evolution reaction (OER). We have developed a new Co_1−xP_v catalyst that has both cobalt defects and phosphorus vacancies, demonstrating excellent OER performance. Under both basic and acidic media, the catalyst incurs a modest overvoltage, with 238 mV and 249 mV needed, respectively, to attain a current density of 10 mA cm⁻². In the practical test of alkaline electrocatalytic water splitting (EWS), the Co_1−xP_v || Pt/C EWS shows a low cell voltage of 1.51 V and superior performance compared to the noble metal-based EWS (RuO₂ || Pt/C, 1.66 V). This catalyst’s exceptional catalytic efficiency and longevity are mainly attributed to its tunable electronic structure. The presence of cobalt defects facilitates the transformation of Co²⁺ to Co³⁺, while phosphorus vacancies enhance the interaction with oxygen species (*OH, *O, *OOH), working in concert to improve the OER efficiency. This strategy offers a new approach to designing transition metal phosphide catalysts with coexisting metal defects and phosphorus vacancies, which is crucial for improving energy conversion efficiency and catalyst performance. 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

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. Full article

With the intensification of global resource shortages and the environmental crisis, hydrogen energy has garnered significant attention as a renewable and clean energy source. Water splitting is considered the most promising method of hydrogen production due to its non-polluting nature and high hydrogen concentration. However, the slow kinetics of the two key reactions, the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER), have greatly limited the development of related technologies. Meanwhile, the scarcity and high cost of precious metal catalysts represented by Pt and Ir/RuO₂ limit their large-scale commercial application. Thus, it is essential to develop catalysts based on Earth’s transition metals that have abundant reserves. Vanadium (V) is an early transition metal with a distinct electronic structure from late transition metals such as Fe, Co, and Ni, which has been emphasized and studied by researchers. Numerous vanadium-based electrocatalysts have been developed for the HER and OER. In this review, the mechanisms of the HER and OER are described. Then, the compositions, properties, and modification strategies of various vanadium-based electrocatalysts are summarized, which include vanadium-based oxides, hydroxides, dichalcogenides, phosphides, nitrides, carbides, and vanadate. Finally, potential challenges and future perspectives are presented based on the current status of V-based electrocatalysts for water splitting. 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