LAUSR

Abstract MgAlCr-CrO42−-LDHs materials were prepared via a hydrothermal method by doping Cr3+ in hydroxide laminates and inserting colored CrO42− to replace the interlayer anions of LDHs materials. This method can optimize the performance of photocatalysis. The samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy, Fourier infrared spectrometry, X-ray photoelectron spectroscopy, and UV–VIS–NIR spectrophotometry. Density functional theory was used to calculate the electron density of states. The effects of Cr3+ and CrO42− on the structure, morphology, electronic structure, VIS-NIR spectrum, and photocatalytic properties were systematically studied, especially the synergistic enhancement effect on the spectrum and catalysis property of MgAl-LDHs materials. The results indicated that the impurities of Cr3+ introduced double characteristic absorption peaks at 400 nm and 570 nm, which improved the absorption of the visible light spectrum of MgAl-LDHs. The CrO42− anion reduced the band gap width, thus enhancing the absorption of low-energy photons. Under the synergistic influence of these effects, the VIS absorptance of MgAl-LDHs was enhanced by 57%, and the color changed from white to dark brown, which proved that the absorption of solar radiation was significantly enhanced. Finally, the interaction between cations and anions enhanced the photocatalytic performance, leading to an apparent photodegradation rate (Kapp) and half-life (t1/2) of methylene blue that reached 0.0174 min−1 and 40 min, respectively. This study is expected to provide a new approach for designing high-performance hydrotalcite photocatalytic materials.