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Infrared Spectroscopy of Ultrablack Films Based on Electrodeposited Ni-P Alloys
Abstract
Ultrablack films produced by etching electrodeposited Ni-P (5.5 at% P) coatings in an oxidizing medium were studied by infrared spectroscopy. It was shown that nickel phosphates and pyrophosphates of different compositions in addition to nickel oxide were the main fi lm components.
... It was shown in [26,27] that an increase in the phosphorus content on the coating surface can be achieved by treating it in a nitric acid solution. However, the phase composition and structure of the surface layers enriched in phosphorus are poorly studied [28], and the possibility of obtaining nickel phosphide phases as a result of heating the treated coatings has not been investigated either. ...
Nickel phosphides NixPy are a promising family of binary compounds that have shown much promise in various fields of technology, including energy storage, light absorption and heterogeneous catalysis in the reactions of biomass hydrogenation. The performance of NixPy-containing materials depends greatly on their morphology and phase composition and, in turn, on the synthesis technique. In this work, we have employed the electroplating approach to synthesize a Ni-P coating, which was treated with nitric acid in order to develop its surface area and enrich it with phosphorus. We have employed scanning electron microscopy, X-ray diffraction and 31P nuclear magnetic resonance techniques to characterize the particles separated from the coating with ultrasound for the convenience of the study. According to experimental data, the obtained powder contained a mixture of Ni3P and phosphorus oxides, which transformed into nickel phosphide phases richer with phosphorus, such as Ni5P2 and Ni12P5, after treatment at elevated temperatures. Thus, we have demonstrated that electroplating followed by acid treatment is a feasible approach for the synthesis of Ni-P coatings with increased surface area and variable phase composition.
... Along with the enhancemento fl aser pulse energy,t he percentage of Ni 3 + gradually increases (Figure 4), and so does the catalytic performance of CoNiPO 4 (L) (Figure 4a nd Figure S15). The CoNiPO 4 (L) produced at the pulse energy of 541 mJ achieves the lowest overpotential, and furtheri ncrease of the pulse energy leads to worse performance, which should be attributed to the decompositiono f phosphate, [43,44] according to the infrared spectrum (Figure S16). ...
Cost‐effective, highly efficient and stable non‐noble metal‐based catalysts for the oxygen evolution reaction (OER) are very crucial for energy storage and conversion. Here, an amorphous cobalt nickel phosphate (CoNiPO4), containing a considerable amount of high‐valence Ni³⁺ species as an efficient electrocatalyst for OER in alkaline solution, is reported. The catalyst was converted from Co‐doped Ni2P through pulsed laser ablation in liquid (PLAL) and exhibits a large specific surface area of 162.5 m² g⁻¹ and a low overpotential of 238 mV at 10 mA cm⁻² with a Tafel slope of 46 mV dec⁻¹, which is much lower than those of commercial RuO2 and IrO2. This work demonstrates that PLAL is a powerful technology for generating amorphous CoNiPO4 with high‐valence Ni³⁺, thus paving a new way towards highly effective OER catalysts.
Light absorbing materials are of practical importance in the production of optical devices in aerospace technology. A new method of light absorbing coatings preparation on the basis of electrodeposited nickel-phosphorus coatings has been proposed. Modification of the electrolyte for nickel-phosphorus plating by the addition of saccharine allowed preparing an ultrablack surface with a reflectance coefficient less than 0.5%. Chemical composition of both surfaces has been studied using X-ray photoelectron spectroscopy. The mechanism of their formation has been proposed. It has been found that etching in nitric acid leads to the partial oxidation of both surfaces with the formation of needle like microstructure.It also results in surface enrichment with phosphorus and formation of nickel phosphides particles of the variable composition. Products of the coating oxidation represent the matrix of amorphous nickel polyphosphates and polyphosphoric acids where fine Ni-P particles are distributed. Such composite structure is a well light absorbing medium. Formation of hypophosphite protective layer on the Ni–P coating obtained from saccharin free electrolyte reduces the thickness of light absorbing layer and changes its composition. Thus light absorbance ability of the coatings can be caused by both distribution of fine nickel-phosphorus particles in dielectric matrix and specific microstructure of their surfaces.
This paper reports that novel method to tune the reflection properties of the ultra-black nickel–phosphorus (Ni–P) film by anodization of the Ni–P films in non-oxide acid electrolyte. The Ni–P films (x%, x stands for mass percentage of phosphorus), which possess both crystalline and amorphous structure with a thickness of 10 μm confirmed by XRD and SEM, were obtained by electroless deposited method on Al substrates. The blacking process of the Ni–P film is first divided definitely into two parts involving acid etching and oxidation testified by XPS and SEM. The mechanism study on blacking process demonstrates the acid etching introduces the change in morphology inducing the presence in conical cavities with minute hairlike structures and decreasing the reflectance; oxidation brings on the change in chemical composition enhancing the absorption capacity. The ultra-black Ni–P film with an etched pore depth of 5 μm obtained by anodization method demonstrates easiness of control and operation, strong adhesion and low reflectance (0.45%). Therefore, this work provides a facile approach for the tunable fabrication of the ultra-black Ni–P film based on anodization method in non-oxidizing acid electrolyte, which can be practical applied in fields of black coating.
DTA in conjuction with X-ray diffraction analysis with a high-temperature camera and infrared spectroscopy was employed to
determine the mechanism of oxidation of Ni-P alloys. Amorphous Ni-P powders were obtained from a nickel(II) sulphate bath
as a nickel source and sodium dihydrophosphate(I) as a reducing agent. The crystallization product is composed of two phases:
(f.c.c.) Ni and (b.c.t.) Ni3P. The amorphous to crystalline transformation takes place in the temperature range 280–330C. Ni3P samples were heated from room temperature to 1050C in air atmosphere at 5C min−1. It was found that the first stage of oxidation of Ni3P goes through the intermediate phase of Ni12P5 formation to Ni2P. Some exothermic reactions were observed. Heating runs were interrupted after each reaction for crystal structure determination
by IR spectrometry. Infrared spectra are reported and it is shown that the structure units present in the amorphous products
at about 700C were the oxoanions PO3
− and P2O7
−. The final products of the oxidation process are NiO and Ni3(PO4)2.
Novel insights into the manufacture of nickel–phosphorus black surfaces by chemical etching of electroless-deposited Ni–P alloy has been achieved by examining the influence of pre-etch phosphorus composition and etching method on the resulting morphology, composition and reflectance of the black surface produced. An optimum phosphorus composition and etching regime to produce low reflectance blacks of 0.4% or lower in the visible region is proposed. Cross-sectional analysis of the etched surface has allowed, for the first time, an accurate determination of the scale of the enhanced morphologies produced and the thickness of the oxidised black layer itself. AFM studies have also provided information on the phase structure of the as-deposited Ni–P alloy.
A mixed-conducting complex oxide La2NiO4+δ was prepared by complex sol–gel method. Both ethylene diamine tetraacetic acid (EDTA) and citric acid (Cit) were used as ligands. A dense supported membrane of La2NiO4+δ was fabricated by coating the sol on a porous α-Al2O3 substrate and followed by heat treatment. A single-phase La2NiO4+δ membrane was obtained at 1123 K which is much lower than the temperature needed for conventional solid-state synthesis. The thickness of the membrane is about 40 μm measured by weight method, and there is no cracks detectable by gas chromatography. X-ray diffraction (XRD) and IR spectrometry verify the presence of K2NiF4-type structure. δ is experimentally determined to be 0.15–0.19. The oxygen flux of the supported membrane, measured by the steady-state method, is not less than 0.3 ml cm−2 min−1 at 923 K, which is significantly higher than that of the bulk membrane made from by particle sintering similar material, showing its great potential for the application in both air separation and catalytic membrane reactor.
Ultra-black materials with low reflectivity can be applied in many fields of science and technology. We deposited nickel-phosphorus
alloys (Ni-P) on copper substrate with the electroless plating method and etched the electroless plating with nitric acid
in order to build ultra-black surface. On the one hand, the components of the Ni-P ultra-black surface layer were investigated
by XRF and XPS. SEM represented that there are innumerable conical holes with the different diameters on the surface. XRD
showed that the whole surface has become amorphous. On the other hand, compared to electroless blackening film by oxidation
and black chromium plating materials, the Ni-P ultra-black surface showed lower wavelength dependence and lower reflectance
in the range of 380–780nm. In addition, the temperature of the sample with the Ni-P ultra-black surface increased more highly
and quickly compared to the black chromium plating film after exposure in an IR laser for about half an hour.
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