Novel Method for Preparing NH₄NiPO₄·6H₂O: Hydrogen Bonding Coacervate Selective Self‐assembly

Abstract

The single phase NH 4 NiPO 4 •6H 2 O was synthesized by solid-state reaction at room temperature using NiSO 4 •6H 2 O and (NH 4 ) 3 PO 4 •3H 2 O as raw materials. The NH 4 NiPO 4 •6H 2 O and its calcined products were characterized using X-ray powder diffraction (XRD), thermogravimetry and differential thermal analyses (TG/DTA), Fourier transform IR (FT-IR), ultraviolet-visible (UV-vis) absorption spectroscopy, and scanning electron microscopy (SEM). The results showed that the product dried at 80 ℃ for 3 h was orthorhombic NH 4 NiPO 4 •6H 2 O [space group Pmm2(25)], and surfactant polyethylene glycol (PEG)-400 can direct growth of crystal NH 4 NiPO 4 •6H 2 O. The thermal process of NH 4 NiPO 4 •6H 2 O experienced three steps, which involve the dehydration of the five crystal water molecules at first, and then deamination, dehydration of the one crystal water, intramolecular dehydration of the protonated phosphate groups together, at last crystallization of Ni 2 P 2 O 7 . The product of thermal decomposition at 150 ℃ for 2 h, orthorhombic NH 4 NiPO 4 •H 2 O, is layered compound with an interlayer distance of 0.8370 nm.

Synergy Derived from Bimetal Co−Cu in Phosphate to Enables Ultrafast Catalytic Hydrogenated Activity in Nitrophenol Reduction

“…The bending mode of the H−O−H group appears around 1690 cm −1 , suggesting the presence of crystalline water molecules in the structure, which favors the proposed crystalline structure. The antisymmetric stretching mode of PO 4 is visible in the range of ∼1100 to 1050 cm −1 , while the band at ∼950 cm −1 corresponds to the symmetric stretching modes of PO 4 , and the bands located at ∼625 and 560 cm −1 are due to the presence of the PO 4 tetrahedral in the structure . These characters confirm the typical metal phosphate structure together.…”

Controllable Fabrication and Tuned Electrochemical Performance of Potassium Co–Ni Phosphate Microplates as Electrodes in Supercapacitors

“…In addition, FT-IR was used to reveal the existing chemical bonds in as-prepared KCo 0.33 Ni 0.67 PO 4 ·H 2 O. As shown in Figure d, these peaks are dominated by the fundamental vibrations of the PO 4 3– polyanions, which were approximately 1150, 1028, 925, 848, and 565 cm –1 . , Moreover, broad bands located at approximately 3387 and 2358 cm –1 refer to the hydroxyl vibrations, and the peaks at 1677 cm –1 are ascribed to H–O–H bending mode in KCo 0.33 Ni 0.67 PO 4 ·H 2 O. , …”

Polypyrrole-Modified NH4NiPO4·H2O Nanoplate Arrays on Ni Foam for Efficient Electrode in Electrochemical Capacitors

“…Transition metal phosphates are inexpensive electrochemically active materials that exhibit broad and potential applications in catalysis, magnetism, and energy storage fields. − Among them, hydrated ammonium metal­(II) phosphate (NH 4 M II PO 4 ·H 2 O, M II = Mn, Fe, Co, and Ni) exhibits a layered structure, which has possibly improved the diffusion of ions and electrons for Faradaic redox reactions in SCs. − Recently, various micro- and nanoscale NH 4 M II PO 4 ·H 2 O with different morphologies and compositions, such as NH 4 CoPO 4 ·H 2 O nanoplates, NH 4 NiPO 4 ·H 2 O microflowers, mesoporous NH 4 NiPO 4 ·H 2 O, and NH 4 CoPO 4 -supported Au and Ag, were fabricated as electrodes and exhibited satisfactory electrochemical performance. − However, the previously reported capacitance value is still far from its theoretical value (e.g., approximately 2000 F g –1 for NH 4 NiPO 4 at 1.5 A g –1 ).…”

“…To efficiently improve the specific capacitance, electrode materials growing on Ni foam provide a favorable electrical conductivity, low diffusion resistance to ionic species, easy electrolyte penetration, and large electroactive area. − Thus, far, although various electrode materials including transition metal oxides, hydroxides, and polymers have been successfully composited on active substrates, − the growth of NH 4 M II PO 4 ·H 2 O on conductive substrates has not been reported for electrodes. As most methods for fabricating NH 4 M II PO 4 ·H 2 O have generally involved rapid coprecipitation, − which will easily generates NH 4 M II PO 4 ·H 2 O materials with scattered and large-sized particles on the substrate and difficult to satisfy the demands of compact and large surface areas for high-performance electrode materials. It is important to develop proper synthetic method to seeding active crystals on the surface of Ni foam.…”