Facile synthesis of flower-like Ag nanocube@mesoporous SiO2 and their sensitive SERS performance

Nanoarchitecting Hierarchical Mesoporous Siliceous Frameworks: A New Way Forward

“…Among various naturemimicking models, the MSN-based dendritic silica constructs with flower-shaped packing and radial-like direct mesoporous channels offer the advantages of direct and convenient access to the encapsulated guest species due to the presence of a combination of highly tunable small-as well as large-sized pores (Gao et al, 2017;Zheng et al, 2018). These structures can be fabricated by appropriately monitoring the reaction conditions, such as altering of solvent, adding the co-solvent like diethyl ether, structure-directing template, and hydrolysis additives, emulsification of reaction solution, and utilization of catalyst (for instance, triethanolamine), which iScience Review would substantially influence the reorganization of deposited silica on the pre-MSN core (Gao et al, 2017;Wang et al, 2019a;Zheng et al, 2018). In this vein, the utilization of diethyl ether as a co-solvent had resulted in the multiple morphologies using the biphasic emulsion (O/W) system, in which the wrinkle-shaped architectures were also evident (Du and Qiao, 2015;Wang et al, 2019b).…”

“…Nevertheless, this approach suffers from a shortcoming of the detachment of the resultant unstable cones during their application, which requires strict optimization of the processing parameters for the fabrication of highly stable architectures. Further, several efforts have been put forward to address the issues through certain advancements such as the addition of hydrolysis additives, for instance, urea, as well as a co-solvent (cyclohexane) and surfactants (cetyl pyridinium bromide) (Das et al, 2019;Gao et al, 2017;Wang et al, 2019a;Zheng et al, 2018). In addition, an external stimulus, for instance, light, can be applied, in which the light-assisted decomposition of urea to ammonium hydroxide resulted in the hydrolysis of added silica precursor.…”

“…The self-assembly of resultant silicate molecules on CTAB micelles during the condensation reaction would lead to the dandelion flower-like geometrical morphology with elongated spikes and different architectures for carbon dioxide (CO 2 ) capture (Figures 8E and 8F) (Das et al, 2019). In addition to surfactants, several surface ligands (4-mercaptophenylacetic acid and poly (acrylic acid)) can be used to support in the establishment of multi-nucleation sites over the core materials, such as MNPs, that support in the formation of overlapped silica islands, resulting in the flower-like morphology (Wang et al, 2019a). Utilization of different solvents, such as n-butanol and cyclohexane, leads to the formation of bicontinuous microemulsion at the low surfactant concentrations, referring to the so-called ''Winsor III system'', resulting in the altered condensation of silica hydrolyzed by urea over the CTAB aggregated on the MNP cores.…”