title: Superior Catalytic Performance of Gold Nanoparticles Within Small Cross-Linked Lysozyme Crystals.
abstract: Bionanomaterials synthesized by bioinspired templating methods have emerged as a novel class of composite materials with varied applications in catalysis, detection, drug delivery, and biomedicine. In this study, two kinds of cross-linked lysozyme crystals (CLLCs) with different sizes were applied for the in situ growth of Au nanoparticles (AuNPs). The resulting composite materials were characterized by light microscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The catalytic properties of the prepared materials were examined in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). It was found that the size of the AuNPs increased with an increase in Au loading for both small and large crystals. In addition, small crystals favored homogeneous adsorption and distribution of the metal precursors. And the size of the AuNPs within small crystals could be maintained below 2.5 nm by managing the HAuCl4/lysozyme molar ratio. Furthermore, the lysozyme functional groups blocked the AuNP activity sites, therefore reducing their catalytic activity. This effect was more pronounced for small AuNPs. Moreover, the mass transfer of reactants (4-NP) from solution to AuNPs within the crystals restricted their catalytic reduction, leading to superior catalytic performance of the AuNPs within small cross-linked lysozyme crystals (Au@S-CLLCs) compared to those within large cross-linked lysozyme crystals (Au@L-CLLCs) at similar Au loadings. Finally, an increase in Au loading clogged the crystal channels with increased quantities of larger AuNPs, thus impeding the catalytic performance of Au@S-CLLCs.
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.
authors.forename: Libing
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Tianjin University , Tianjin 300072, P. R. China.
authors.forename: Renliang
authors.initials: R
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.|Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072, P. R. China.
authors.forename: Rongxin
authors.initials: R
authors.lastname: Su
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.|Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Qi
authors.affiliation: State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, P. R. China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: He