High entropy spinel oxide for synchronized solar-driven evaporation and water purification

High entropy spinel oxide (HESO) with five or more metal elements randomly distributed in the crystalline oxide lattice, can exhibit unique physical and chemical characteristics. Herein, we present a HESO composed of Ni, Cu, Zn, Co, and Mn as a multi-functional photocatalyst for synchronized photothermal-photodegradation reactions. Experimental evaluation and density functional theory (DFT) calculation analysis reveal that the HESO with optimized quasi-metallic properties affords high solar energy harvest efficiency with an excellent solar evaporation rate of 2.6 kg·m⁻²·h⁻¹ and 83.9% evaporation efficiency under 1 sun irradiation. Simultaneously, the diverse metal ions in the octahedral sites facilitate long-distance charge carrier transfer pathways within HESO, achieving the 94.3% removal of tetracycline (TC) within 20 min via photocatalysis at a concentration of 0.3 g·L⁻¹ assisted by visible-light-driven activation of peroxymonosulfate (PMS). Long-term cycling tests for photothermal-photodegradation demonstrate the reliability and reusability of HESO in practical applications. This finding provides a new perspective to design the multi-functional photothermal photocatalysts for simultaneous photodegradation and clean water production.