| Cuprous delafossite oxides are a family of copper-based complex oxides uniquely structured with alternating layers of linearly coordinated O-Cu I-O and MIIIO6 edge-shared octahedra. This structure is responsible for several interesting properties, such as p-type conductivity through a delocalized Cu 3d- and O 2p- orbital valence band, susceptibility to both extrinsic acceptor doping and oxygen intercalation, and high optical transparency. However, reported applications of these oxides have been relatively limited, especially compared to perovskite-structured oxides. One reason for this is likely the difficulties faced controlling morphology, impurities, and doping in their syntheses. The work presented here starts with this synthetic challenge, first focusing on the synthetic chemistry in understanding the phase formation and crystallization of CuScO2, then from the observed properties of CuScO2, the potential application of delafossite oxide as oxygen electrocatalysts is proposed and investigated.;The properties of CuScO2, a potential p-type transparent conducting oxide, lead to several synthetic challenges. Significant oxygen intercalation within copper layer means control of oxidation proves difficult by the conventional solid state syntheses. Through consideration of copper and scandium species hydrolysis, the first hydrothermally synthesized pure-phase CuScO2 is reported. Post-annealing treatments were used to investigate the influence of oxygen intercalation and were found to increase copper oxidation, leading to increased light absorption, and flat-band potential shifts.;The observed oxygen intercalation in CuScO2 led to an original research proposal and subsequent demonstration of cuprous delafossite oxides as catalysts for the alkaline oxygen reduction reaction. The delafossite structure possesses several key elements that could potentially make it desirable for ORR catalytic applications: the presence of lowcoordination Cu-sites, accessible by O2 molecules, and the ability to alter lattice space around Cu-sites by changing the size of the MIII cation. CuLaO 2 was found to have the most prevalent complete reduction of oxygen out the oxides tested.;Finally, preliminary studies on the use of CuLaO2+x as a potential low temperature solid oxide fuel cell cathode material for low temperature oxygen reduction are presented. The experimental setup and custom fabricated cell holder are detailed, followed by electrochemical impedance spectroscopy tests to compare the oxide to commercially available cathode materials. The CuLaO2+x phase shows potential at very low temperature (< 400 °C), and promising new directions are discussed.;Cuprous delafossite oxides provide a unique framework for tuning chemical and catalytic properties. Focus on individual copper and scandium species hydrolysis led to the first reported phase-pure CuScO2 hydrothermal synthesis. The presented rationale can be applied to other delafossite oxides, allowing for improved morphology and doping control. The first demonstration of cuprous delafossite oxides as alkaline oxygen reduction catalysts and investigation of their low temperature catalytic properties show the potential for tunable copper sites in a variety electrocatalytic processes involving oxygen species. |
