Size dependence of silver nanoparticles in carboxylic acid functionalized mesoporous silica SBA-15 for catalytic reduction of 4-nitrophenol

Zhang

et al. 2018

Adv Funct Materials

Microorganisms are widely used as the biotemplates for producing micro/ nanomaterials owing to their unique features, such as exquisite morphology, renewable, and environmentally friendly. However, mass intracellular synthesis of uniformly dispersed nanoparticles (NPs) inside microorganisms is still challenging, especially in a predictable and controllable manner. Here, a facile and efficiency strategy is proposed to controllably produce highly dispersed and surfactant-free Pd@Ag core-shell NPs within the Spirulina platensis (Sp.) cells. In this approach, the Sp. cells' permeability is enhanced by the hydrochloric acid treatment first, which enables the Pd NPs penetrate the cell envelope and distribute uniformly inside the cells, and then they can work as the catalytic seeds for the following electroless silver deposition, resulting in the intracellular fabrication of Pd@Ag core-shell NPs with no agglomeration. The Pd@Ag NPs show excellent catalytic activity (turnover frequency is up to 2893 h −1 for the 6.32 nm Pd@Ag NPs), good stability, and recyclability toward the 4-nitrophenol reductions. The excellent properties are attributed to the asymmetrical core-shell structure, small size, and good dispersion of Pd@Ag NPs. Due to its facility, cost-effectiveness, and versatility, this method can be expanded to other microorganisms, so it opens tremendous opportunities for various metallic nanoparticles intracellular synthesis as well as the practical application.

Section: Resultscontrasting

confidence: 54%

Facile Fabrication of Highly Dispersed Pd@Ag Core–Shell Nanoparticles Embedded in Spirulina platensis by Electroless Deposition and Their Catalytic Properties

Zhang

et al. 2018

Adv Funct Materials

“…Moreover, the use of copper nanoparticles (CuNPs) is restricted by Cu’s inherent instability under atmospheric conditions, which makes it prone to oxidation. Some supporting materials increase the stability of CuNPs by altering their sensitivity to oxygen, water, and other chemical entities, which has encouraged the exploration of alternative Cu-based NPs with more complex structures [ 12 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Dual Stimuli-Responsive Copper Nanoparticles Decorated SBA-15: A Highly Efficient Catalyst for the Oxidation of Alcohols in Water

et al. 2020

In the present work, a temperature and pH-responsive hybrid catalytic system using copolymer-capped mesoporous silica particles with metal nanoparticles is proposed. The poly(2-(dimethylamino)ethyl methacrylate)(DMAEMA)-co-N-tert-butyl acrylamide) (TBA)) shell on mesoporous silica SBA-15 was obtained through free radical polymerization. Then, copper nanoparticles (CuNPs) decorated SBA-15/copolymer hybrid materials were synthesized using the NaBH4 reduction method. SBA-15 was functionalized with trimethoxylsilylpropyl methacrylate (TMSPM) and named TSBA. It was found that the CuNPs were uniformly dispersed in the mesoporous channels of SBA-15, and the hybrid catalyst exhibited excellent catalytic performance for the selective oxidation of different substituted benzyl alcohols in water using H2O2 as an oxidant at room temperature. The dual (temperature and pH-) responsive behaviors of the CuNPs/p(DMAEMA-co-TBA)/TSBA catalyst were investigated using the dynamic light scattering technique. The conversion of catalytic products and selectivity were calculated using gas chromatographic techniques, whereas the molecular structure of the products was identified using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The catalyst showed excellent catalytic activity toward the oxidation of alcohol to aldehyde in an aqueous medium below the lower critical solution temperature (LCST) and pKa values (7–7.5) of the copolymer. The main advantages of the hybrid catalyst, as compared to the existing catalysts, are outstanding alcohol conversion (up to 99%) for a short reaction time (1 h), small amount of the catalyst (5 mg), and good recyclability equal to at least five times.

“…Very recently, Kao et al [46] reported the formation of Ag NPs inside the mesoporous silica SBA-15 functionalized with -COOH groups as the support. The acetate (-COO − ) groups effectively interacted with the Ag + ions, thus allowed for a facile fabrication of small-sized Ag NPs down to 3.0 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the catalytic activities of Ag NPs-loaded silica SBA-15 composites toward the reduction of 4-NP in the presence of NaBH 4 was investigated by Guo and coworkers [47]. The particle size of Ag plays a definitive role in determining their catalytic activity [46,47]. Furthermore, uniform sized spherical, and rod-shaped Ag NPs have been successfully deposited inside the mesochannels of SBA-15 via a simple chemical method [48].…”

Section: Introductionmentioning

confidence: 99%

Study on catalytic efficiency of platinum and silver nanoparticles confined in nanosized channels of a 3-D mesostructured silica

et al. 2020

A scalable route to encapsulate homogeneously fine Pt and Ag nanoparticles (NPs) inside amine-functionalized KIT-6 mesochannels via two different reduction routes as heterogeneous mesoporous catalysts is demonstrated. The active amine groups functionalized KIT-6 mesochannels act as anchor sites to immobilize the homogeneous Pt and Ag NPs catalysts with small-sized NPs of approximately 6.0 and 3.0 nm, respectively. The catalysts were fully characterized, and the surface areas were relatively decreased after deposition of the metals NPs. Even after metal NPs deposition, the mesochannels are readily accessible for enhancing their catalytic activity. The meso-KIT-6-Pt catalyst synthesized with ascorbic acid (AA) reduction route shows a higher catalytic efficiency for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a reaction rate almost 2 times higher than that of the meso-KIT-6-Ag synthesized using formaldehyde. The as-prepared mesoporous catalysts exhibit a good reusability, with a high catalytic efficiency for at least 5 successive cycles without an obvious loss in their catalytic activity. The influences of reaction parameters, such as catalyst dose, reaction temperarture and nature of solvent on the catalytic performance of the mesoporous catalysts are of the main study.