Mineralization and Self-assembly of Gold Nanoparticles using Sulfur Amino Acid Modified Hierarchically Porous Metal-Organic Frameworks

摘要

In this work, we modified the hierarchically porous metal-organic frameworks (HP-MOFs) HP-UiO-66 with sulfur-containing amino acid cysteine and methionine, respectively. The cysteine or methionine modified HP-MOFs, HP-UiO-66-C and HP-UiO-66-M, can be used for the adsorption and mineralization of Gold nanoparticles. Au nanoparticles will form in HP-MOFs when the concentration of chloroauric acid is relatively low. Intriguingly, when the concentration of the chloroauric acid solution was increased to 5 mgml~(-1), hexagonal gold micro flakes appeared in the system after adsorption by the HP-UiO-66-C and HP-UiO-66-M. Transmission electron microscope revealed that the hexagonal gold micro flakes are formed by the ordered self-assembly of gold nanoparticles induced by the HP-UiO-66-C and HP-UiO-66-M. The obtained AuNP@HP-UiO-66-C and AuNP@HP-UiO-66-M can catalyze the reduction of 4-NP. The apparent reaction rates constant of unit mass catalyst k_(cat) are 0.0356 mg~(-1) min~(-1) and 0.0265 mg~(-1) min~(-1), respectively.