Nickel Phosphate Research Articles

Boosting Hydrogen Evolution Behaviors of Porous Nickel Phosphate by Phosphorization Engineering

A stable and efficient porous nickel phosphate (p-NiPO/Ti) electrocatalyst on titanium sheets was developed via electrochemical deposition and low-temperature phosphatization. For obtaining the optimal performance of the p-NiPO/Ti electrocatalyst, the optimized experimental parameters of deposition and phosphatization were determined by parallel experiments. After the preparation, XPS and XRD were used to validate the chemical and amorphous structure, with SEM and TEM simultaneously validating a distinct nanosheet/nanocluster crosslinked microstructure. In particular, with phosphatization conditions maintained at 300 °C for 10 min, the p-NiPO/Ti produced demonstrated excellent charge transfer and catalytic characteristics in 1.0 M KOH. The electrocatalytic results revealed that the optimal p-NiPO/Ti with excellent catalytic performance and excellent stability (~24 h) needs lower HER overpotentials (128 mV at 10 mA cm−2 and 242 mV at 100 mA cm−2) as inputs. This research provides a promising strategy with which to use transition metal materials as catalysts in alkaline electrocatalytic hydrogen production.

Exploratory mass dispersoid rGO in-situ influence on nickel phosphate-trimesic acid metal-organic framework for higher energy density hybrid supercapacitors

The present study investigates effect of reduced graphene oxide (rGO) mass dispersoid @ 25, 50, 75, and 100 mg through in-situ process into Metal Organic Framework based Nickel Phosphate (MOFNP) synthesized by facile microwave technique. The XRD study confirms monoclinic crystalline geometry and 50 mg rGO dispersed MOFNP (MOFNPG2) composite has shown increase in crystallinity. SEM shows rectangular morphology for MOFNPG2 and Raman studies show ID/IG ratio of 1.01 for this composite revealing rGO coordination with MOFNP. BET studies reveal higher specific surface area (59.75 m2 g−1) for MOFNPG2 and exhibits mesoporosity (3.14 nm) with type-IV Langmuir isotherm. The deconvoluted XPS spectra confirms oxidation states and chemical compositions of MOFNPG2. The CV profile identifies maximum oxidation for MOFNPG2, revealing EDLC / pseudocapacitance contribution and exhibiting higher specific capacitance of 854 F g−1 @ 1 A g−1. The Full-Cell Device (FCD) MOFNPG2//rGO registers 175 F g−1 @ 1 A g−1 and energy density 79 Wh kg−1. The Resr is lower (0.19 Ω cm−2) for FCD which improvises electrode-electrolyte kinetics and results in enhanced conductivity for high energy density supercapacitor applications.

A cheap and straightforward method for the selective isolation of histidine-derived natural products using nickel(II) phosphate.

Nickel-based resins have long been used in biochemical studies for the purification of His-tagged proteins, but their potential in the isolation of histidine-derived small molecules has not been investigated to date. Many agriculturally-important mycotoxins incorporate histidine residues, as do natural products from both plants and bacteria. Here, a highly-selective solid-phase extraction method is described for the purification of histidine-derived natural products using the insoluble nickel salt Ni3(PO4)2. This led to the highly-selective binding and elution of two natural products, meleagrin and gartryprostatin C, from two fungal strains, Penicillium chrysogenum and Aspergillus sclerotiorum, respectively. A simple protocol involving binding, washing with water and methanol, and elution with methanolic acetate buffer, gave 65-75% recovery of both compounds directly from crude extracts of the two fungi. The procedure can easily be used as part of a multi-step isolation process in combination with HPLC to yield the purified alkaloids.

Amperometric Highly Sensitive Phosphate Ion Sensor Based on the Electrochemically Modified Ni Electrode.

We present a study of high-performance electrochemical phosphate sensors, which are exquisitely designed and easy to operate. We innovatively utilized the insolubility of nickel phosphate and developed a new type of sensor through electrochemical methods. The experiment first used cyclic voltammetry to determine -0.4 V as the optimal electrochemical modification potential and used constant potential electrodeposition technology to form a nickel oxide layer on the surface of the nickel electrode, which serves as the active layer in response to phosphate ions. The changes in the surface structure and chemical composition of the electrode before and after modification were thoroughly characterized by scanning electron microscopy and energy scattering spectroscopy analysis. The performance evaluation of the sensor shows that the modified nickel electrode has excellent responsiveness to phosphate ions in the concentration range of 10-7 to 10-10 mol/L, with a detection lower limit of 10-10 mol/L. As the concentration decreases, a shoulder peak appears at ∼0.63 V and the current change shows a regular increase. Compared with traditional detection methods, this sensor exhibits higher stability and practicality and is suitable for the rapid identification of phosphates in real samples. In summary, this study successfully developed a fast, sensitive, and wide response range current type electrochemical phosphate sensor, which has broad application prospects in environmental monitoring, water quality analysis, and biomedical fields.

Modification of nickel foam with nickel phosphate catalyst layer via anodizing for boosting the electrocatalytic urea oxidation and hydrogen evolution reactions

Urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) are the key processes for implementing urinated water electrolysis and hydrogen green production, respectively. This contribution investigates the modification of commercial nickel foam (NF) with a nickel phosphate (NiPO/NF) heterostructure layer via anodizing in phosphate solution at various potentials (5, 10 and 15 V) as a simple and efficient route to boost the urea-assisted water electrolysis and hydrogen production in alkaline medium. The morphology and composition physicochemical characterisation of the phosphate layer exhibit aggregates of crystalline nanoparticles with interstitial mesoporous and macroporous networks with a mole composition ratio of 9.42: 1.0: 8.14 for Ni: P: O respectively. The electrochemical measurements revealed the NiPO/NF anodized at 10 V exhibits a superior electroactive surface area of 255 cm2, a substantially higher urea oxidation current compared to pristine NF, achieving 20 and 500 mA/cm2 at 1.35 and 1.6 V vs. RHE respectively and retained 100 % of activity during the urea electrolysis for more than 3 h. The electrochemical impedance analysis confirmed the alkaline urea oxidation reaction proceeded via indirect (EC) and direct mechanism and the CO2 intermediates adsorption–desorption became the predominant reaction at more positive potential. The NiPO/NF anode employed in an H-shape can deliver up to ±400 mA/cm2 for UOR/HER at a bias potential of 1.85 V and 8-fold (2.0 mmol/min) much higher hydrogen production rate compared to the pristine NF anode (0.25 mmol/min). Combining commercial nickel foam modification via anodizing and alkaline urea electrolysis at ambient conditions offers a unique and innovative solution for both large-scale hydrogen green production as well as remedy of the urinated wastewater for a more sustainable future.

Preparation of Ni2P with a Surface Nickel Phosphosulfide Layer by Reduction of Mixtures of Na4P2S6 and NiCl2

AbstractA series of physical mixtures of Na4P2S6 and NiCl2 (P‐NiPS(x), where x represents the P/Ni molar ratio) were employed for the preparation of Ni2P. For comparison, a sulfur‐containing Ni2P catalyst (Ni2P‐S) and a sulfur‐free Ni2P catalyst (Ni2P‐TPR) were prepared by reduction of Ni2P2S6 and a nickel phosphate precursor, respectively. The reduction of the P‐NiPS(x) precursors with P/Ni ratios above 2/3 yielded Ni2P catalysts with a distinct nickel phosphosulfide layer (NiPS(x)), and the Ni2P phase started to form at ca. 200 °C. The reduction of Ni2P2S6 to Ni2P most likely follows a disproportionation mechanism. The P3+ species in Ni2P2S6 disproportionate to PH3 and P5+ during the reduction, and PH3 further reacts with nickel and sulfur species to form Ni2P and the surface nickel phosphosulfide layer. The sulfur atoms in the nickel phosphosulfide phase were in the form of S2−. The introduction of sulfur to Ni2P favored the hydrogenation pathway of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), but hardly affected the direct desulfurization (DDS) pathway and inhibited the hydrogenation of biphenyl. The DDS pathway rate constants of DBT HDS over the Ni2P‐TPR and NiPS(x) catalysts were observed to increase linearly with the increase in their surface Ni atomic concentrations.

Synthesis, Structures, and Magnetic Investigations of Nickel Phosphates: Ni2(PO4)(OH), Ni7(PO4)3(HPO4)(OH)3, and NaNiPO4 Including Potential Haldane Behavior.

Three novel nickel-phosphate structures are reported, Ni2(PO4)(OH) (I), Ni7(PO4)3(HPO4)(OH)3 (II), and NaNiPO4 (III). Each new system was prepared via a high-temperature hydrothermal synthesis at 600-650 °C. All three compounds are built of quasi-one-dimensional (quasi-1-D) Ni2+ containing chains with varying phosphate bridging modes and were characterized by single crystal X-ray diffraction and magnetic susceptibility. All three compounds display very different magnetic behavior. Anisotropic magnetic data is reported for Ni2(PO4)(OH) (I) exhibiting slow antiferromagnetic ordering in the high-temperature regime with substructures that begin to form below 32 K at different field strengths. These characteristics affirm I as being one of the few Haldane-like material candidates. The Ni7(PO4)3(HPO4)(OH)3 (II) material is a member of the unusual ellenbergerite structural family and displays complex inter- and intrachain magnetic interactions while NaNiPO4 (III) shows antiferromagnetic ordering near 18 K. This magnetic behavior is correlated with their structures.

Transformative impact of molybdenum on nickel phosphate hydrate electrodes towards superior energy storage application

Development of high capacity and long cycle life electrode materials is essential to improving energy storage capacity in electrochemical rechargeable devices. In order to be commercially viable, the synthesis of these materials must be straightforward, cost-effective, and ideally a single-step process. We present a binder-free synthesis method for nickel phosphate hydrate (NiPH) and nickel molybdenum phosphate hydrate (NiMoPH) on nickel foam via a simple hydrothermal process. X-ray diffraction (XRD) patterns confirmed the formation of NiPH and NiMoPH phases, while X-ray photoelectron spectroscopy (XPS) verified the presence of nickel (Ni), molybdenum (Mo), phosphorus (P), and oxygen (O) in the composite. Scanning electron microscopy (FE-SEM) revealed the formation of micro-flowers with plate-like structures in NiPH, which transformed into hexagonal rod-like structures upon the introduction of molybdenum in NiPH. This morphological and phase modification increased the charge storage capacity from 1441 mF/cm2 (NiPH) to 2945 mF/cm2 (NiMoPH) at 20 mA/cm2. The NiMoPH electrode demonstrated excellent capacitance retention of 91.8 % over 10,000 cycles. Additionally, asymmetric supercapacitor (ASS) devices were fabricated using NiPH and NiMoPH as positive electrodes and activated carbon (AC) as the negative electrode. The NiPH//AC and NiMoPH//AC configurations exhibited energy densities of 0.086 and 0.201 mWh/cm2, respectively, with the NiMoPH//AC device maintaining about 90 % capacitance retention over 15,000 cycles. This study demonstrates the potential of incorporating conductive transition metals to enhance electrode material performance in energy storage applications.

Synthesis of ultrathin carbon layer-coated LiNiPO4 nanoparticles by solvothermal method

The emerging market of high-power lithium-ion batteries (LIBs) highlights the importance of developing high-voltage cathodes. Lithium nickel phosphate (LiNiPO4) with the highest theoretical discharge potential (∼5.1V) has attracted increasing attention due to its stable olivine structure. In this study, ultrathin carbon layer-coated LiNiPO4 was synthesized using oleylamine-assisted solvothermal method under different solvothermal times, and the effect of solvothermal time (1h–18h) on LiNiPO4 samples is fully investigated. X-ray diffraction (XRD) shows that high-purity LiNiPO4 materials can be prepared after calcination of the solvothermal product under N2, but adding part of H2 to the calcination atmosphere will lead to the generation of impurities in the target product. As the solvothermal time increases, the product will agglomerate and grow, the particle size will increase, and the morphology will change from nanoparticle to rodlike structure. After the high-temperature calcination step, the oleylamine is completely carbonized, and a conductive carbon layer is successfully coated on the LiNiPO4 with the thickness of 2 nm. As the solvothermal time increases, the graphitization degree of oleylamine increases after carbonization. The existence of the carbon layer and the increase in the degree of graphitization are beneficial to improving the electrical conductivity and Li-ion diffusion rate of LiNiPO4. The initial discharge capacity of LNP@C-12h product prepared with 12 h solvothermal time is 35 mA h g−1 at 0.1 C. Rietveld analysis shows that the anti-site defect concentration of the LNP@C material is 1.07 %, and the proportion increases to 2.83 % after several cycles. This work provides a positive contribution to the synthesis and modification of high-voltage LiNiPO4 materials and explains the electrochemical performance degradation of LiNiPO4 from the perspective of increasing the concentration of anti-site defects.

Constructing Nickel Phosphate Polymorph Heterojunctions by In Situ Cr-Induced Structural Transition for Enhanced Bifunctional Electrochemical Water Splitting

Constructing Nickel Phosphate Polymorph Heterojunctions by In Situ Cr-Induced Structural Transition for Enhanced Bifunctional Electrochemical Water Splitting

A battery-type cathode with RuO2 modified Ni11(HPO3)8(OH)6 for asymmetric supercapacitors

Phosphates are a kind of promising electrode materials because they can provide numerous cavities and several reaction sites to be favored for storing anions and cations. However, the widespread application of phosphates are limited by their intrinsically low electronic conductivity. RuO2/hydrated RuO2 exhibits high conductivity and excellent electrochemical properties. Reducing its dosage and increasing its specific surface area are the research concerns. Combining less RuO2 to Nickel phosphate (NiP) is expected to improve the electrochemical performance. RuO2-modified NiP (NiP-RuO2) electrode material is synthesized by a one-step hydrothermal reaction and its structural morphology and capacitive properties are investigated. The results indicate that NiP-RuO2 electrode consists of hydrated RuO2 and Ni11(HPO3)8(OH)6, and exhibits excellent battery-type electrochemical supercapacitor performance with a specific capacity of 878.06 C/g at 1 A/g. According to density functional theory (DFT) analysis, Ru-doped Ni11(HPO3)8(OH)6 has a narrower forbidden band width and higher conductivity than Ni11(HPO3)8(OH)6. Furthermore, the asymmetric supercapacitor (ASC) assembled by NiP-RuO2/NF and activated carbon (AC) electrode achieves a high energy density (43.58 Wh/kg) at a power density of 923.47 W/kg. When two ASC devices are connected in series, ten light-emitting diodes (LEDs) can be illuminated for ten minutes.

Synthesis of nickel phosphate nanowires as a bifunctional catalyst for water electrolysis in alkaline media

The electrocatalytic water splitting (WS) process for hydrogen (H2) and oxygen (O2) production is known for its high efficiency, necessitating the development of bifunctional electrode materials. These materials must possess strong catalytic activity, significant active sites, high stability, and an abundance of earth-friendly components to ensure efficient and prolonged H2 and O2 generation. In this study, we employed a hydrothermal method to synthesize unique one-dimensional (1D) nickel phosphate (NiPO) nanoneedles directly grown on nickel foam (NF). The in-situ synthesis of the NiPO/NF catalyst offers favorable streamlining, facilitating electrode production and improving the contact between active sites and the conductive substrate. Under alkaline conditions, the NiPO/NF electrodes demonstrated low overpotentials of 374 mV and 377 mV at a high current density (J) of 250 mAcm−2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. These values indicate efficient and stable electrocatalytic activity. Moreover, the NiPO/NF catalyst exhibited continuous bifunctional catalytic activity for 12 hours with a J exceeding 20 mAcm−2. These findings suggest that NiPO/NF has the potential to be a cost-effective and sustainable option for large-scale WS applications.

Crystallinity transformation engineering of hydrous cobalt nickel phosphate cathodes for hybrid supercapacitor devices: Extrinsic/battery to intercalation type pseudocapacitors

The necessitating strategies of rationalizing nanostructures and crystallinity of electrode material are crucial to developing high-efficiency hybrid energy storage devices. To enhance the energy storage performance of bimetal phosphates, it is important to have a strategic blend of metal cations that can work together synergistically. So, this work describes the scalable preparation of binder-free cobalt nickel phosphates thin film cathodes with cations variation (Co/Ni) via the facile Successive Ionic Layer Adsorption and Reaction (SILAR) process. The distinct roles of cations in cobalt nickel phosphate electrodes resulted in a noteworthy structural transformation from crystalline to amorphous with an increment of Ni content. The change in cations composition influences the pseudocapacitive performance from extrinsic/battery to intercalation type, and cobalt nickel phosphate electrode with an ideal cations composition (Co:Ni) ratio of approximately 1:1 attain the highest specific capacitance (SCs) of 2142 F g−1 (1071 C g−1). To fulfil the demand for high-performance hybrid supercapacitor devices, aqueous (HASC) and solid-state (HSSC) supercapacitors are assembled using optimized cobalt nickel phosphate (S-CNP5) as a cathode. The HASC device represents maximum SCs of 120 F g−1 with specific energy (SE) and specific power (SP) of 42.59 Wh kg−1 and 1600 W kg−1, respectively. The flexible HSSC device shows impressive SCs of 89 F g−1 and SE of 31.54 Wh kg−1 at SP of 2057.14 W kg−1. The practical demonstration of an HSSC device to power a 12-white LED lamp suggests that the SILAR strategy offers commercializing insights for fabricating high-specific capacity hydrous cobalt nickel phosphate thin film cathodes.

Mechano-chemical hydrothermal synthesis of NH4NiPO4·H2O and its transformation to LiNiPO4

Powder preparation of materials that can be used in production cathodes can be simplified by development of mechanical synthesis. In this paper, we report a novel approach using mechano-chemical hydrothermal synthesis of NH4NiPO4·H2O (Ammonium Nickel Phosphate Hydrate – ANP) was investigated. This method is easily scalable and is characterized with great repeatability. It uses inexpensive raw materials: NH4H2PO4 and NiCO3·Ni(OH)2·4H2O for one step synthesis without external source of heating. Reaction between substrates was conducted in water environment by planetary ball milling. As a result of high attrition inside milling chamber, both temperature and pressure is rising. By modification of conditions morphology of obtained powders can be modified. The produced ANP powders with phase purity up to 94.3 vol% (XRD measurement), were transformed to LiNiPO4 (Lithium Nickel Phosphate - LNP) by mixing with finely grinded Li2CO3 and calcination at 500 °C for 2 h. It resulted in LNP content of up to 91.2 vol% in final samples (XRD measurement). The mechano-chemical hydrothermal method was proved to be successful in terms of obtaining LNP using a dissolution – precipitation mechanism during wet milling at room temperature.

Calcium-, magnesium-, and yttrium-doped lithium nickel phosphate nanomaterials as high-performance catalysts for electrochemical water oxidation reaction

Abstract Electrochemical water oxidation reaction (WOR) lies among the most forthcoming approaches toward eco-conscious manufacturing of green hydrogen owing to its environmental favors and high energy density values. Its vast commoditization is restricted by high-efficiency and inexpensive catalysts that are extensively under constant research. Herein, calcium, magnesium, and yttrium doped lithium nickel phosphate olivines (LiNi1−x M x PO, LNMP; x = 0.1–0.9; M = Ca2+, Mg2+, and Y3+) were synthesized via non-aqueous sol-gel method and explored for catalytic WOR. Lithium nickel phosphates (LNP) and compositions were characterized via Fourier transform infrared, scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray diffraction techniques for the structural and morphological analyses. Glassy carbon electrode altered with the LNMPs when studied in a standard redox system of 5 mM KMnO4, displayed that yttrium doped LNP, i.e. LNYP-3 exhibits the highest active surface area (0.0050 cm2) displaying the lowest average crystallite size (D avg) i.e. ∼7 nm. Electrocatalytic behavior monitored in KOH showed that LNMP-2 offers the highest rate constant “k o,” value, i.e. 3.9 10−2 cm s−1 and the largest diffusion coefficient “D o,” i.e. 5.2 × 10−5 cm2 s−1. Kinetic and thermodynamic parameters demonstrated the facilitated electron transfer and electrocatalytic properties of proposed nanomaterials. Water oxidation peak current density values were indicative of the robust catalysis and facilitated water oxidation process besides lowering the Faradic onset potential signifying the transformation of less LNP into more conducive LNMP toward water oxidation.

Synthesis of Nickel Phosphate Using Self Templated Method

Nickel phosphate has diverse applications, such as in glucose sensors, catalysts, and supercapacitors. Different synthesis methods affect its structure and properties, characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis. Metal phosphates have high ion conductivity, chemical stability, and unique 1D nanostructures. Self-templating techniques, like templating against colloidal particles, create hollow 1D metal phosphate structures, determined by the template size. Materials including triethyl phosphate and ethanol, were used in a self templated method to synthesize different forms of nickel phosphate with varying triethyl phosphate volumes, resulting in products labelled as nickel phosphate-500, nickel phosphate-800, and nickel phosphate-1000. The observation under SEM showed that microflower structures are formed while the XRD analysis revealed that the nickel phosphate material had an amorphous structure with randomly arranged particles, evident from the single broad peak in the XRD patterns. The current response showed that nickel phosphate-500 exhibited the highest reading with the value of 0.2 mA compared to the other two nickel phosphates.

Understanding the role of precursor concentration in the hydrothermal synthesis of nickel phosphate hydrate for supercapacitors

Understanding the role of precursor concentration in the hydrothermal synthesis of nickel phosphate hydrate for supercapacitors

Enhanced electrochemical performance: Synergetic effect of time-dependent synthesis and redox additive concentration on ammonium nickel phosphate hydrate

Transition metal phosphates (TMP) have emerged as compelling candidates for supercapacitors because of their exceptional structural, chemical, and electrochemical properties. For the enhancement of energy density (Ed) of TMP, the use of redox-additive (RA) electrolytes is a cutting-edge trend because of the tuning between the electrode and electrolyte, which is much simpler than the fabrication of complex electrodes. Ammonium nickel phosphate hydrate powders (ANPh's) have been prepared via the hydrothermal method with varying reaction times (3, 6, and 9 h) at the constant reaction temperature of 180°C. The formation of ANPh's has been confirmed by structural and compositional analysis. The morphological analysis revealed the microplate-like architecture of ANPh's. The specific capacitance (Cs) of the optimized ANPh_6 electrode (EANPh_6) in KOH electrolyte observed 496 F g−1 with an Ed of 11.03 Wh kg−1 and a power density (Pd) of 404 W kg−1 at 10 mA cm−2 with 78.79 % retention after the 5000th galvanostatic charge-discharge (GCD) cycle at 100 mA cm−2. However, to overcome the problem of poor Ed and capacitance retention in aqueous electrolytes, the electrochemical properties of EANPh_6 are studied in RA electrolytes with varying concentrations (0.010 M to 0.020M) results in enhancement in electrochemical performance by improving redox reactions at the EANPh_6 and KOH electrolyte interface. The EANPh_6 with 0.015 M potassium ferricyanide K4Fe(CN)6 boosted 3 times greater Cs 1516 F g−1 and Ed 33.70 Wh kg−1 with Pd 487 W kg−1 at 10 mA cm−2 with enhanced cyclic stability of 87.54 % over the 5000 GCD cycles at 100 mA cm−2. The symmetric aqueous state device, EANPh_6// EANPh_6, achieved Cs, Ed, and Pd of 48.51 F g−1, 1.07 Wh kg−1, and 292.68 W kg−1 at 30 mA cm−2 current density with remarkable capacitance retention of 98 % over 5000 GCD cycles at 80 mA cm−2. Finally, it is anticipated that identifying the optimized electrode with an appropriate concentration of RA will be one of the eminent techniques to boost the electrochemical properties.

Leveraging phosphate group in Pd/PdO decorated nickel phosphate microflowers via pulsed laser for robust hydrogen production in hydrazine-assisted electrolyzer

By driving the electrooxidation of small molecules instead of relying on sluggish oxygen evolution reaction (OER), low-input voltage is obtained for overall water splitting (OWS) and hydrogen generation, requiring active electrocatalysts. Using single-step pulsed laser irradiation, strong metal-support interaction is achieved on Pd/PdO-decorated Ni3(PO4)2·8H2O (NiPh) microflowers, yielding an outstanding bifunctional electrocatalyst for hydrogen evolution (HER) and hydrazine oxidation (HzOR). When Pd/PdO-NiPh-3 serves as both anode and cathode in the OWS electrolyzer (OER||HER), a cell voltage of 2.098 V achieves 10 mA/cm2 in 1.0 M KOH. When evaluated in the hydrazine-coupled electrolyzer (HzOR||HER), Pd/PdO-NiPh-3 exhibits remarkable stability with a low cell voltage of 0.538 V in 0.5 M-N2H4/1.0 M-KOH, which is approximately 1.56 V lower than that of the traditional water electrolyzers. In Pd/PdO-NiPh, the empty 4s and 5s orbitals of Ni2+ and Pd, respectively, serve as two absorption sites. These sites facilitate chemisorption on the electrocatalyst surface by forming a two-electron dipolar bond between the lone-pair electrons of NH2 groups in N2H4 and Ni2+ as well as Pd. A feasible strategy for utilizing Pd/PdO-NiPh catalysts in developing direct N2H4 fuel cells is investigated in this work, enabling the simultaneous production of robust energy-saving H2 fuel and electricity.

Sonochemically synthesized novel CNTs-PANI/CoNi(PO4)2 nanocomposites with enhanced electrochemical energy storage performance for asymmetric supercapacitor applications

Carbon nanotubes (CNTs) were polymerized with polyaniline (PANI) via an in-situ polymerization approach. These functionalized CNTs (PANI-CNTs) were added in various concentrations to the sono-chemically synthesized Co-Ni binary transition metals phosphate (CoNi(PO4)2) to ultimately have their nanocomposites. Electron microscopy (SEM & HRTEM) was employed to reveal the morphology and microscopic features. The structural evaluation of metal phosphate and PANI/CNTs was done by X-ray diffractometer analysis, whereas chemical grafting of cobalt nickel phosphate (CoNi(PO4)2) was done by Fourier transformed infrared spectroscopy and Raman spectroscopy. The hierarchical structured CoNi(PO4)2 with 40 mg PANI/CNTs mass (CNP40) presented enhanced specific capacity of 1268 Cg−1 (2136 F g−1 at 1.5 F g−1) with excellent diffusive behavior (b = 0.5). A resulted hybrid supercapacitor device consisting of CNP40 as +ve electrode and activated carbon AC) as −ve electrode, presented excellent energy density of ∼87 Whkg−1 with good power density of 680 W kg−1 maintained to 32.9 W kg−1 (@ 20,400 W kg−1) with 37% rate performance, and excellent cyclic performance (∼100%) after 5000 charge-discharge cycles. Furthermore, capacitive-diffusive analysis revealed that the device showed 55% diffusive and 45% capacitive behaviour. This improved electrochemical performance might be attributed mainly to the uniform and hierarchical chemical grafted morphology of the novel combination of binary phosphates and PANI functionalized CNTs in the nanocomposite obtained via a rather different sonochemical approach.