Regulating the Co₃O₄@NiMn-LDH nano heterojunction for efficient photoelectrocatalytic water purification

Photoelectrocatalytic (PEC) degradation of refractory antibiotics has attracted great interest in recent years, thereinto, the selection and design of efficient catalysts is particularly pivotal. With the in-depth study of semiconductor materials, the composite electrodes which can inhibit the recombination between electrons and holes have made significant progress in the field of PEC. Herein, the Co₃O₄@NiMn-LDH photoanode with stratified core-shell heterostructure was prepared and its removal process of sulfamethoxazole (SMX) was evaluated. The study showed that the constructed heterostructures had the following advantages: (i) the nutrient transporting arteries of Co₃O₄ nanoneedle acted as charge transport channels to promote the induced charge migration and separation; (ii) The petal-like NiMn-LDH nanosheets were significantly adjustable and had excellent charge storage capabilities, which could remarkably collect solar energy leading to more active species; (iii) the pollutants could be gathered on the "spider network" surface of Co₃O₄@NiMn-LDH by electrostatic adsorption proved by DFT calculations, which was conducive to electrolyte penetration and utilization of the active site. The optimized Co₃O₄@NiMn-LDH-3.00 catalyst showed excellent PEC degradation activity and stability for SMX (initial removal rate of 98.00 %, removal rate of 75.12 % after five cycles). Based on the energy band matching and morphology construction proposed in this study, this unique layered core-shell heterostructure could be expected to achieve excellent PEC performance through synergistic effects.