Cu2FeO3

Cu2FeO3 is a copper–iron oxide with a 2:1 copper-to-iron ratio. It has attracted attention as a functional oxide for electronics and catalysis. The compound can host copper in mixed valence states (Cu+ and Cu2+) and iron in variable oxidation states, with the precise valence distribution controlled by synthesis conditions and oxygen activity.

Synthesis and structure: Cu2FeO3 is typically prepared by high-temperature solid-state reaction from CuO and Fe2O3 in air or oxygen, often above 800–1000 °C, sometimes with post-annealing to improve phase purity. It has been reported to crystallize in more than one polymorph; structural descriptions include delafossite-like and other oxide frameworks depending on temperature and preparation method. Non-stoichiometry and secondary phases can complicate synthesis and interpretation of measurements.

Properties: It is a semiconducting oxide with absorption in the visible region; optical band gaps reported in the literature generally fall in the range of about 1.5–2.0 eV. The material often shows p-type conductivity, with transport influenced by copper valence and oxygen vacancies. Stability under reducing conditions can be limited, potentially leading to phase changes or decomposition.

Applications: Research has focused on photocatalysis for degradation of pollutants and for visible-light driven water splitting, as well as potential use as an electrode material in energy storage. Practical devices remain challenged by issues such as phase purity, long-term stability, and scalable synthesis.

See also: related copper–iron oxide systems such as CuFeO2, CuFe2O4, CuO, and Fe2O3.