Construction of a flower-like MgAlZn-LDO@ZnO composite via Zn-assisted structural regulation for enhanced adsorption-assisted photocatalytic removal of basic fuchsin

A flower-like MgAlZn layered double oxide/zinc oxide composite (MgAlZn-LDO@ZnO) was prepared through the thermal conversion of a Zn-regulated MgAlZn layered double hydroxide (MgAlZn-LDH) precursor and subsequent coupling with ZnO obtained by a deep eutectic solvent (DES)-assisted route. Different from conventional LDH/LDO-based composites mainly constructed by direct component combination, this work uses Zn²⁺ as a structural regulator to control the growth and assembly of LDH nanosheets, reduce excessive stacking, and promote the formation of a more dispersed three-dimensional flower-like architecture. After calcination, the hierarchical morphology of the precursor was largely retained, and ZnO was uniformly attached to the surface of MgAlZn-LDO. Compared with MgAl-LDH, the obtained MgAlZn-LDO@ZnO composite showed a larger specific surface area, a more developed pore structure, and improved surface hydrophilicity. Photoelectrochemical results showed that MgAlZn-LDO@ZnO possessed a higher photocurrent response and lower charge-transfer resistance than the corresponding LDH precursor, indicating improved separation and migration of photogenerated charge carriers. Under identical reaction conditions, 95.3% of basic fuchsin (BF) was removed within 50 min by MgAlZn-LDO@ZnO, whereas the removal efficiencies of MgAl-LDH and pure ZnO were 52% and 59%, respectively. Radical trapping experiments showed that ·OH was the dominant active species, while ·O₂⁻ also participated in the photocatalytic oxidation process. DFT calculations indicated that the amino groups and adjacent conjugated regions of BF were more likely to be attacked by reactive species. The enhanced adsorption-assisted photocatalytic removal performance was mainly ascribed to the combined effects of Zn²⁺-regulated structural dispersion, LDO-assisted interfacial enrichment, and ZnO-driven charge separation, which together promoted the adsorption–photocatalytic degradation of BF. Download: Download high-res image (192KB) Download: Download full-size image