Preparation of Amine-Modified Cu-Mg-Al LDH Composite Photocatalyst.

Cu-Mg-Al layered double hydroxides (LDHs) with amine modification were prepared by an organic combination of an anionic surfactant-mediated method and an ultrasonic spalling method using N -aminoethyl- γ -aminopropyltrimethoxysilane as a grafting agent. The materials were characterized by elemental analysis, XRD, SEM, FTIR, TGA, and XPS. The effects of the Cu 2+ content on the surface morphology and the CO 2 adsorption of Cu-Mg-Al LDHs were investigated, and the kinetics of the CO 2 adsorption and the photocatalytic reduction of CO 2 were further analyzed. The results indicated that the amine-modified method and appropriate Cu 2+ contents can improve the surface morphology, the increase amine loading and the free-amino functional groups of the materials, which were beneficial to CO 2 capture and adsorption. The CO 2 adsorption capacity of Cu-Mg-Al N was 1.82 mmol·g -1 at 30 °C and a 0.1 MPa pure CO 2 atmosphere. The kinetic model confirmed that CO 2 adsorption was governed by both the physical and chemical adsorption, which could be enhanced with the increase of the Cu 2+ content. The chemical adsorption was suppressed, when the Cu 2+ content was too high. Cu-Mg-Al N can photocatalytically reduce CO 2 to methanol with Cu 2+ as an active site, which can significantly improve the CO 2 adsorption and photocatalytic conversion.