UBC Theses and Dissertations
Amorphous electrocatalysts formed by near-infrared-driven decomposition Salvatore, Danielle Aline
The splitting of water into hydrogen and oxygen is widely viewed as the most sustainable option for storing energy produced by intermittent renewable energy sources such as solar or wind. Economically feasible large-scale deployment of this type of system requires the discovery of efficient electrocatalysts, particularly for the kinetically slow oxygen evolution reaction (OER). Transition metal oxides are the most durable and active water oxidation catalysts, and there is a growing body of evidence showing amorphous metal oxide films mediate the OER more efficiently than the crystalline phases of the same compositions. Notwithstanding, there is a limited set of fabrication methods available for making amorphous films, particularly in the absence of a conducting substrate. I introduce herein a scalable preparative method for accessing oxidized and reduced phases of amorphous films that involves the efficient decomposition of molecular precursors, including simple metal salts, by exposure to near-infrared (NIR) radiation. The NIR-driven decomposition process provides sufficient localized heating to trigger the liberation of the ligand from solution-deposited precursors on substrates, but insufficient thermal energy to form crystalline phases. This method provides access to state-of-the-art electrocatalyst films, as demonstrated herein for the electrolysis of water, and extends the scope of usable substrates to include non-conducting and temperature-sensitive platforms. Because crystalline ruthenium oxide is one of the most efficient electrocatalysts in acidic media, it would be highly advantageous to be able to readily access the amorphous phase of the material. I also document two facile preparation techniques for accessing amorphous ruthenium oxide, a state-of-the-art electrocatalyst. The formation of amorphous ruthenium oxide films is triggered by the decomposition of a film of spin-cast molecular ruthenium precursors on conducting glass by either ultraviolet (UV) and near infrared (NIR) light.
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