Noncrystalline structure of Ni–P nanoparticles prepared by liquid pulse discharge

Abstract

Noncrystalline nickel phosphide (Ni-P) nanoparticles have drawn great attention due to their high potential as catalysts. However, the structure of noncrystalline Ni-P nanoparticles is still unknown, which may shed light on explaining the catalysis mechanism of the Ni-P nanoparticles. In this paper, noncrystalline Ni-P nanoparticles were synthesized. Their morphology, particle size, element contents, local atomic structures, as well as the catalysis in the thermal decomposition of ammonium perchlorate were studied. The results demonstrate that the as-prepared Ni-P nanoparticles are spherical with an average diameter of about 13.5 nm. The Ni and P contents are, respectively, 78.15% and 21.85%. The noncrystalline nature of the as-prepared Ni-P nanoparticles can be attributed to cross-linkage between P-doping f.c.c.-like Ni centers and Ni3P-like P centers. The locally ordered Ni centers and P centers are the nuclei sites, which can explain well the origin of initial nuclei to form the crystalline phases after high-temperature annealing. The starting temperature of high-temperature decomposition of ammonium perchlorate was found having a significant decrease in the presence of the noncrystalline Ni-P nanoparticles. Therefore, the as-prepared noncrystalline Ni-P nanoparticles can be used as a potential catalyst in the thermal decomposition of ammonium perchlorate.

In Situ Time-Resolved X-ray Absorption Fine Structure and Small Angle X-ray Scattering Revealed an Unexpected Phase Structure Transformation during the Growth of Nickel Phosphide Nanoparticles

“…For comparison, Figure 2a also included XANES spectra from a standard Ni foil (6 μm) and the final noncrystalline Ni−P nanoparticles, whose noncrystalline nature has been well described in our previous reports. 41 The spectrum at 0 s is corresponding to the freshly prepared reaction solutions without pulse discharge, in which the content of metallic Ni was considered as 0. Noticeably, the sharp white line peak in Figure 3a showed a gradual decrease in intensity and a slight lower energy side shift in position along with the reaction time, which could be attributed to the decrease of averaged chemical valence of Ni.…”

Intense Femtosecond Laser-Mediated Electrical Discharge Enables Preparation of Amorphous Nickel Phosphide Nanoparticles

“…Si and O elements can be attributed to the substrate SiO 2 ; therefore, it can be concluded that the as-prepared nanoparticles were composed only of Ni and P. The inset of Figure d shows that the atomic ratio of phosphorus increases with increasing laser power, which demonstrates the flexibility of this synthesis method in controlling the nanoparticle composition. This kind of noncrystalline Ni–P nanoparticles are considered to be very interesting and valuable because of their potential applications in catalytic activity, such as thermal decomposition of AP, , hydrogen evolution reaction, − or HDS reaction …”

“…To better understand the formation procedure of the as-prepared nanoparticles, taking the underlying synthesis mechanism into consideration is extremely necessary. In previous studies, Tan et al reported successful preparation of Ni–P nanoparticles via a liquid pulse discharge method. ,, In their work, a peak voltage of 1200 V was applied between a pair of needle-like electrodes about 3 mm apart, which equaled approximately to an average electric field of 4 × 10 5 V/m assuming that this electric field between the electrodes was uniform. Actually, this electric field was not like this, meaning that relatively stronger regions and other relatively weaker regions existed simultaneously.…”

“…Previous studies have revealed that amorphous Ni−P nanoparticles possess prominent catalytic capability that can speed the decomposition procedure or decrease the decomposition temperature of AP. 1,2,42 In our experiment, the thermal decomposition process of AP with the addition of the as-synthesized Ni−P nanoparticles was investigated by the TG-DTA test. Figure 6 compares the catalytic performance results between AP mixed with and without the amorphous Ni−P nanoparticles.…”

“…Nickel phosphide (Ni–P) nanoparticles have excellent electric, magnetic, and optical properties, such as thermal decomposition of ammonium perchlorate (AP) (a key energy material for rocket propellants), , hydrodesulfurization (HDS), hydrodenitrogenation, hydrogen evolution reaction, − magnetic storage, , electrode materials for Li batteries, − and water splitting, − which make them ideal catalysts for various energy materials. In addition, they are good conductors of heat and electricity, and they also have high thermal and chemical stability .…”