Borane–Aluminum Surface Interactions: Enhanced Fracturing and Generation of Boron–Aluminum Core–Shell Nanoparticles

Abstract

We present an experimental and theoretical study of borane−aluminum surface interactions that lead to rapid production of aluminum nanoparticles when Al balls are milled in the presence of diborane or pentaborane. Mass spectrometry was used to probe reactions of the boranes with aluminum fracture surfaces produced by milling collisions, which also generate local, transient high temperatures. Density functional theory was used to examine the interactions between a model aluminum surface and diborane and pentaborane, providing insight into the energetics of the first steps in the process that ultimately enables nanoparticle production. Further insight into the surface chemistry was obtained by analyzing the nanoparticles with X-ray photoelectron spectroscopy, scanning transmission electron microscopy with both electron-energy-loss and energy-dispersive X-ray spectroscopies, and dynamic light scattering. Particles were found to have fcc aluminum cores, capped by a ∼2-nm-thick shell, rich in both boron and hydrogen. The shell partially protects the aluminum from air oxidation, and further capping of the particles with organic ligands renders the particles air-stable and confers dispersibility in hydrocarbon solvents.

Diborane Interactions with Pt7/Alumina: Preparation of Size-Controlled Borated Pt Model Catalysts

“…Diborane TPD/R was done by exposing samples to B 2 H 6 at 130 K sample temperature, followed by heating to 700 K. For ethylene TPD/R, the sample was exposed to 5 langmuirs of C 2 D 4 at a sample temperature of 150 K (to minimize multilayer adsorption), cooled to 130 K, and then heated to 700 K while monitoring signals for C 2 D 4 + , D Boron was introduced into the UHV system in the form of a diborane/argon gas mixture that we characterized mass spectrometrically to have actual composition of 4.8% diborane, 85% argon, and 10.2% H 2 , the latter assumed to result from diborane decomposition during storage. 35 Diborane exposures were calculated based on the measured diborane mole fraction. In most experiments, boration was done by exposing the samples to 1.5 langmuirs of diborane at a sample temperature of 130 K, followed by heating to 700 K, which was found to be sufficient to drive desorption to completion.…”

“…Boron was introduced into the UHV system in the form of a diborane/argon gas mixture that we characterized mass spectrometrically to have actual composition of 4.8% diborane, 85% argon, and 10.2% H 2 , the latter assumed to result from diborane decomposition during storage . Diborane exposures were calculated based on the measured diborane mole fraction.…”

“…Boron was introduced into the UHV system in the form of a diborane/argon gas mixture that we characterized mass spectrometrically to have actual composition of 4.8% diborane, 85% argon, and 10.2% H 2 , the latter assumed to result from diborane decomposition during storage. 33 Diborane exposures were calculated based on the measured diborane mole fraction. In most experiments, boration was done by exposing the samples to 1.5 L of diborane at a sample temperature of 130 K, followed by heating to 700 K, which was found to be sufficient to drive desorption to completion.…”

Experimental synthesis, functionalized modifications and potential applications of monoelemental zero-dimensional boron nanomaterials

“…Typically, an effective modication strategy is to produce core/shell nano-structural derivatives. 79,84,[133][134][135][136][137][138] The derivatives usually consist of 0D boron nanomaterials as the core and other inorganic nanomaterials as the shell. Walton et al prepared boron core silica shell (B@SiO 2 ) nanoparticles, having spherical, monodisperse and water-dispersible features suitable for the aforementioned biomedical applications.…”

Boron alumina: qualitative investigation of the surface acidity by FTIR measurements of CO adsorption

“…Boron alumina (Al 18 B 4 O 33 or 9Al 2 O 3 , 2B 2 O 3 ) is well known as ceramic material that possesses excellent electrical conductivity and chemical inertness properties at high temperatures [1][2][3]. It is also known as a thermostable light-weighted ceramic (density = 2.9 kg dm 3 ) that can be used as refractory materials up to 1700 °C [4,5]. In fact, such ceramic is known as reinforcing material due to its high mechanical resistance along with an extreme chemical resistance in oxidizing conditions and a low thermal expansion coefficient (4.2 × 10 −6 K −1 ) which makes it resistant to thermal shocks [6][7][8][9][10].…”