Fundamental properties of delafossite CuFeO2 as photocatalyst for solar energy conversion

Photocatalysis technology can meet the two global issues of energy shortage and environmental pollution at the same time. Due to the unique layered quasi-two-dimensional superlattice structure, and the specific functions of structural motifs, delafossite compounds have become a popular candidate family for photoelectric conversion applications. In this article, 3R-delafossite CuFeO2 microcrystals with complete stoichiometry, high crystallinity and purity, uniform composition, cubic size of ∼1.47 μm, single crystal phase were obtain by the optimized hydrothermal process. Combined with optical measurement and density functional theory calculation, the electron transition mechanism of CuFeO2 was analyzed in depth and systematically. CuFeO2 has obvious multi-band spectral absorption characteristics, which are helpful to clarify the controversy about band gap values of CuFeO2. CuFeO2 microcrystals exhibit potential hydrogen production from photocatalytic water-splitting to and photocatalytic degradation of pollutants. Tetracycline hydrochloride degradation testing was adopted to further verify the potential of CuFeO2 microcrystals for wastewater purification. CuFeO2 microcrystals not only exhibit excellent photocatalytic degradation performance, but also present Fenton reaction activity in dark conditions after adding H2O2. It is particularly important that the removal rate of tetracycline hydrochloride was significantly enhanced by the coupling of photocatalytic reaction and Fenton reaction, suggesting that CuFeO2 emerges excellent Photo-Fenton reaction activity. Finally, this article not only provides the fundamental physical chemical properties of CuFeO2 for solar energy conversion, but also points out the development direction of further improving the efficiency. An optimized hydrothermal process was adopted to prepare single-phase, high-purity, and high-crystallinity 3R-delafossite CuFeO2 microcrystals. Its electronic structure and optical properties are analyzed in detail, and the disputes and contradictions about its basic band gap and optical band gap are clarified. The photoelectrochemical performances and photocatalytic degradation of tetracycline hydrochloride exhibit the potential of CuFeO2 microcrystal as solar energy converter. The possible directions of further improving its efficiency are also discussed. [Display omitted] •3R-delafossite CuFeO2 with single phase was prepared facile hydrothermal method.•Some controversies about the fundamental pr