Effect of Encapsulation of Boron Nanoparticles Using Reduced Graphene Oxide on their Oxidation Characteristics

Abstract

Boron is a well‐known high‐energy solid. A thick oxide coating on the particle, however, inhibits its ignition and reduces its energy significantly. In this work, graphene nanosheets were used as a protective material for encapsulating boron nanoparticles (NPs) to prevent their oxidation from the air at room temperature. Boron‐reduced graphene oxide (RGO) composites were prepared under hydrothermal conditions using graphene oxide (GO) and commercial or washed boron NPs as precursors. Boron‐RGO composites were characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), thermogravimetry (TG), and differential scanning calorimetry (DSC). XPS data show that no boron oxide or boric acid was present on the surface of washed boron particles and boron‐RGO composites. It seems that the removal of boron oxide or boric acid layer on the commercial boron particle surface and the reduction of graphene oxide occurred simultaneously during hydrothermal treatment. XRD data show that boric acid re‐formed on washed boron NPs but not on the boron‐RGO composites after these two samples had been exposed to ambient temperature air for four months. This indicates that the anti‐oxidation stability of boron against air at room temperature was improved greatly after encapsulation of reduced graphene oxide. The heat of combustion of boron‐RGO composites (46.6∼49.3 kJ ⋅ g−1) measured by oxygen bomb calorimetry was higher than that of the commercial boron NPs (43.4 kJ ⋅ g−1). Upon heating, the boron‐RGO composite begins oxidizing at a lower temperature than the commercial boron particles. A mechanism was proposed for encapsulation of boron NPs with RGO.

Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core–Shell Coating

“…The raw B sample exhibited diffraction peaks at 14.6°, 27.3°, 30.6°, 36.0°, and 39.9°, which can be attributed to the presence of boron oxide and boric acid on the surface of raw B. 44 After acetonitrile washing, characteristic peaks corresponding to boron oxide and boric acid disappeared or weakened in the XRD pattern of B w , indicating successful removal of the oxide layer. The XRD pattern of the B w @6% Viton composite resembled that of B w , with key peak locations remaining primarily unaltered and no new peaks surfacing.…”

“…To investigate the composition of B w @Viton composites, the results of XRD are presented in Figure a. The raw B sample exhibited diffraction peaks at 14.6°, 27.3°, 30.6°, 36.0°, and 39.9°, which can be attributed to the presence of boron oxide and boric acid on the surface of raw B . After acetonitrile washing, characteristic peaks corresponding to boron oxide and boric acid disappeared or weakened in the XRD pattern of B w , indicating successful removal of the oxide layer.…”

Laser-Ablative Aqueous Synthesis and Characterization of Elemental Boron Nanoparticles for Biomedical Applications

“…Results of this measurement are shown in Figure 4. As shown in the gure, the peak at 187.7 eV corresponds to elemental boron (B 0 ), whereas a peak near 192.3 eV corresponds to the oxidized boron state B 3+ , con rming the presence of boron oxide (B 2 O 3 ) and/or boric acid (H 3 BO 3 ) in the upper shell of NPs [34][35][36] . We believe that the formation of boron suboxide (B 6 O) in a negligible quantity is also possible, which could explain a slight broadening of the spectrum around 188 eV.…”