Ultrathin Zirconia Passivation and Stabilization of Aluminum Nanoparticles for Energetic Nanomaterials via Atomic Layer Deposition

Abstract

The stability of aluminum (Al) nanoparticles is a key issue that determines the energy performance of solid fuels, Al-based green propellants, and fuel cells. The surface native oxide shell (Al 2 O 3 ), nevertheless, cannot stabilize Al nanoparticles under hot water conditions. Herein, we report a passivation method utilizing an ultrathin zirconia (ZrO 2 ) coating via atomic layer deposition, where a sub-nanometer coating layer could completely prevent the reactions between Al nanoparticles and hot water (80 °C). The weight percentage of metallic Al for ultrathin ZrO 2 coated Al nanoparticles can reach 82.2 wt %, which is close to that of original Al nanoparticles with Al 2 O 3 native oxide (88 wt %). The metallic Al's weight has been kept at 93.4% for the ultrathin ZrO 2 coated Al nanoparticles compared to the original Al nanoparticles. As a comparison, the Al 2 O 3 coated Al nanoparticles result in the oxidation failure in 60 °C water. The proposed passivation mechanism is attributed to ZrO 2 coating's structural stability and the enhanced hydrophobicity to water. The ultrathin ZrO 2 passivation offers a valuable tool for enhancing the stability of Al nanoparticles and thereby enables their potential applications in energy field.

Superhydrophobic Fluorine‐Containing Protective Coating to Endow Al Nanoparticles with Long‐Term Storage Stability and Self‐Activation Reaction Capability

“…Another point should be noted that water vapor in air also plays an important role in the oxidation process of ANPs as we discussed. Some studies show that organic coatings are permeable to oxygen, leading to the oxidation of internal Al core, however, they can take as a resistance layer to humidity . Surrounding water vapor can be effectively stopped from entering into inside of AFNPs, by contrast, oxidation of ANPs caused by water vapor could be more serious due to its hydrophilic interaction.…”

“…Except for the natural Al 2 O 3 layer, secondary coatings can also offer a protective effect on preventing further oxidation, thereby extending the shelf life of ANPs. Generally, the passivation coating can be divided into two categories based on whether it can serve as an energetic component during the oxidation process of ANPs . One is a nonenergetic layer, such as oleic acid, polydopamine, and zirconia, and the other is an energetic layer, like nitrocellulose, nickel, and iron .…”

“…Generally, the passivation coating can be divided into two categories based on whether it can serve as an energetic component during the oxidation process of ANPs . One is a nonenergetic layer, such as oleic acid, polydopamine, and zirconia, and the other is an energetic layer, like nitrocellulose, nickel, and iron . Although both of the protective layers make contributions to oxidation resistance of metallic core, the latter type seems to be more attractive because it can also increase the energy density and improve the energy‐release rate at elevated temperatures by intermetallic or thermite reactions between the coatings and the core.…”

Dual‐Shelled RbLi(Li3SiO4)2:Eu2+@Al2O3@ODTMS Phosphor as a Stable Green Emitter for High‐Power LED Backlights

“…All the diffraction patterns are indexed to the standard patterns of monoclinic RbLi(Li 3 SiO 4 ) 2 (PDF card No.76‐0344) with a space group of C 2/ m besides very small amounts of Li 4 SiO 4 impurity, indicating these processes do not change the crystallographic structure of the phosphor. There are no diffraction peaks of Al 2 O 3 detected in the XRD patterns of RLSO:Eu 2+ @Al 2 O 3 , which is attributed to the formation of amorphous phase of Al 2 O 3 coating layers . Fourier transformation infrared (FTIR) spectra are used to determine the chemical bond and functional groups present and investigate the surface change of RLSO:Eu 2+ .…”

Surface functionalization on nanoparticles via atomic layer deposition

“…They also developed ZrO 2 and Al 2 O 3 bilayers-coating on metallic Al NPs via ALD as shown in Fig. 3b [49]. Al NPs have a large specific area and high energy release rate.…”