Gallium Nanoparticle Formation and Doping of Nanocrystalline Alumina from a Ga–Al Liquid Metal Hydrogen Generating Reaction

Abstract

We report a liquid metal gallium−aluminum (Ga− Al) composite water splitting reaction, where gallium nanoparticles (Ga NPs) and nanocrystalline aluminum hydroxide [Al(OH) 3 ] are generated simultaneously with the coproduction of green H 2 fuel. This reaction involves the formation of Ga NPs originating from Lewis acid−base nanoclusters composed of Ga and Al NPs. The initial Ga−Al NP liquid composite possesses the ability to cleave the H−O−H bonds of water, resulting in the formation of Ga−H and Al−OH bonds. Under ambient conditions, the Ga−H bonds subsequently metathesize into Ga NPs and H 2 . Interestingly, these Ga NPs undergo gradual oxidation in air, resulting in the doping of the nanoaluminum hydroxide byproduct. Remarkably, this reaction occurs under atmospheric conditions without the need for caustic chemicals, electrolysis, reverse osmosis, inert atmosphere, or external energy input. The reaction products were characterized using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (PXRD), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). We further investigated the influence of various reaction conditions, such as composition of the binary alloy, volume of water used, and temperature, on the resulting byproducts. The nano-Al(OH) 3 byproduct could be successfully calcined to value-added nanocrystalline α-Al 2 O 3 at 1100 °C.