Harnessing intrinsic defect complexes for visible-light-driven photocatalytic activity in Delafossite CuAlO2

This study significantly enhances the photo(electro)catalytic capabilities of CuAlO2, a wide bandgap semiconductor, through targeted defect engineering. By employing a tailored solid-state reaction under a mixed oxygen-argon atmosphere, an intrinsic defect complex of [Oi+CuAl] into has been successfully integrated into CuAlO2, thereby expanding its light absorption to the visible spectrum. The optimized CuAlO2 sample, containing the [Oi+CuAl] complex, demonstrates a remarkable 2.13-fold increase in photocatalytic degradation of tetracycline hydrochloride under visible-light irradiation. The maximum incident photon-to-current conversion efficiency value is elevated from 0 to 3.27%, and the photocatalytic water splitting hydrogen production rate is increased by 10.78-fold. Density functional theory calculations, in conjunction with experimental data, elucidate the role of the [Oi+CuAl] complex in facilitating visible-light absorption and improving the separation of photogenerated electron-hole pairs. Under simulated sunlight, the modified CuAlO2 sample exhibits a substantial 2.26-fold enhancement in photocatalytic degradation of tetracycline hydrochloride, a photocurrent density increase from 0.80 to 8.20 µA·cm−2, and a 1.13-fold increase in photocatalytic hydrogen production rate compared to defect-free CuAlO2. This research underscores the potential of strategic defect engineering to enhance visible-light-driven photo(electro)catalysis in wide bandgap semiconductors.