Photocatalytic degradation performance for high-entropy oxide (La0.2Ce0.2Gd0.2Zr0.2Fex)O2 enriched with defects

High-entropy oxides (HEOs) have been considered promising novel photocatalytic materials due to their tunable compositions, bandgaps, and excellent thermal stability. Investigating the effects of molar ratio of single atoms in HEOs on their crystal structure, defects, and band structures is crucial for realizing their potential photocatalytic applications. We designed and synthesized (La0.2Ce0.2Gd0.2Zr0.2Fex)O2 HEOs by varying the molar ratio of Fe to study its influence on the atomic arrangement, crystal structure, defects, and optoelectronic properties. With increasing molar ratio of Fe, the valence band position of (La0.2Ce0.2Gd0.2Zr0.2Fex)O2 gradually decreased, the crystal structure became more ordered, and the defects decreased. Among them, (La0.2Ce0.2Gd0.2Zr0.2Fe0.05)O2 (H-1) had an appropriate band structure and abundant defects, exhibiting excellent photocatalytic performance. The results showed that the degradation rate of tetracycline reached 95.4% under visible light irradiation for 3 h. After five cycles, its structure and photocatalytic performance remained unchanged. This study lays the foundation for further exploration and optimization of high-entropy oxides for photocatalytic applications.