Ma Yingzhen, Nagy Gergely, Siebenbürger Miriam, Kaur Ravneet, Dooley Kerry M, Bharti Bhuvnesh
Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
J Phys Chem C Nanomater Interfaces. 2022 Feb 10;126(5):2531-2541. doi: 10.1021/acs.jpcc.1c09573. Epub 2022 Jan 26.
The assembled state of nanoparticles (NPs) within porous matrices plays a governing role in directing their biological, electronic, and catalytic properties. However, the effects of the spatial confinement and environmental factors, such as salinity, on the NP assemblies within the pores are poorly understood. In this study, we use adsorption isotherms, spectrophotometry, and small-angle neutron scattering to develop a better understanding of the effect of spatial confinement on the assembled state and catalytic performance of gold (Au) NPs in propylamine-functionalized SBA-15 and MCM-41 mesoporous silica materials (SiO). We carry out a detailed investigation of the effect of pore diameter and ionic strength on the packing and spatial distribution of AuNPs within SiO to get a comprehensive insight into the structure, functioning, and activity of these NPs. We demonstrate the ability of the adsorbed AuNPs to withstand aggregation under high salinity conditions. We attribute the observed preservation of the adsorbed state of AuNPs to the strong electrostatic attraction between oppositely charged pore walls and AuNPs. The preservation of the structure allows the AuNPs to retain their catalytic activity for a model reaction in high salinity aqueous solution, here, the reduction of -nitrophenol to -aminophenol, which otherwise is significantly diminished due to bulk aggregation of the AuNPs. This fundamental study demonstrates the critical role of confinement and dispersion salinity on the adsorption and catalytic performance of NPs.
纳米颗粒（NPs）在多孔基质中的组装状态在决定其生物学、电子学和催化性能方面起着主导作用。然而，空间限制和环境因素（如盐度）对孔隙内NP组装体的影响却知之甚少。在本研究中，我们使用吸附等温线、分光光度法和小角中子散射来更好地理解空间限制对丙胺功能化的SBA - 15和MCM - 41介孔二氧化硅材料（SiO）中金（Au）NP组装状态和催化性能的影响。我们详细研究了孔径和离子强度对SiO内AuNP的堆积和空间分布的影响，以全面了解这些NP的结构、功能和活性。我们证明了吸附的AuNP在高盐度条件下具有抗聚集的能力。我们将观察到的AuNP吸附状态的保持归因于带相反电荷的孔壁和AuNP之间的强静电吸引。结构的保持使AuNP在高盐度水溶液中对模型反应（此处为对硝基苯酚还原为对氨基苯酚）保持催化活性，否则由于AuNP的大量聚集，催化活性会显著降低。这项基础研究证明了限制和分散盐度对NP吸附和催化性能的关键作用。
