Silicon oxide (SiOx) has long been recognized as a versatile material due to its exceptional mechanical strength, thermal stability, low toxicity, and potential for functionalization. It has found applications in various industries, from gels and lubricants to plastics and composites. The conventional Stöber reaction has historically been the go-to method for producing spherical silica nanoparticles, which, while effective, limits the morphology of the particles to spherical shapes. However, the demand for more complex shapes, such as nanosheets and nanorods, has driven researchers to explore alternative synthesis methods. Templating reactions have emerged as a successful strategy for obtaining 2D nanomaterials, where an existing material, such as graphene oxide (GO), serves as a template for the nucleation and growth of the desired nanomaterial. This approach allows for replicating the template’s morphology while simultaneously restricting growth in at least one dimension.
To this account, a new study published in the Journal Nanoscale, a team of researchers from the KTH Royal Institute of Technology in Sweden, led by Dr. Richard Olsson, demonstrated a pioneering approach to fabricating 2D silicon oxide (SiOx) nanosheets with nearly identical dimensions as the graphene oxide (GO) template, opening up exciting possibilities for a wide range of applications, including electronics, semiconductors, energy storage, and catalysis materials.
The research team’s study focuses on the use of graphene oxide (GO) as a template for the synthesis of 2D silicon oxide (SiOx) nanosheets. The methodology involves a controlled condensation reaction using low concentrations of GO (<0.5 wt%) to obtain SiOx nanoflakes with remarkable precision. These nanoflakes closely mimic the lateral dimensions and thickness of the GO sheets, with lateral diameters of approximately 500 nm and thicknesses of around 1.5 nm.
The authors managed to perform successful covalent bonding of silanes with the GO sheets, which replaces the oxygen groups on the GO surface. This bonding ensures the stability and integrity of the resulting SiOx nanosheets. Importantly, the GO template can be entirely removed through thermal treatment without compromising the nanoflake morphology of the pure SiOx material. This scalability is a crucial aspect of the research, as it provides a pathway for large-scale production of SiOx-based 2D nanosheets, a feat not previously reported.
The research team explored two different silane precursors, (3-aminopropyl) triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS), and demonstrated that both precursors effectively templated the graphene oxide template. Molecular modeling revealed that the choice of silane precursor influenced the number of layers coated on the GO sheets, providing a degree of tunability to the synthesis process. Additionally, rheological measurements revealed that the relative viscosity of the resulting particle suspensions was significantly affected by the specific surface area of the synthesized particles.
The synthesized SiOx nanosheets possess several unique properties that make them promising candidates for various applications. Their uniform size, reproducible morphology, and large surface area are particularly noteworthy. The large surface area, a characteristic often associated with 2D nanoparticles, can be advantageous in applications where high surface area is desirable, such as in barrier materials and as carriers for catalysts.
The study also highlights the durability of the SiOx nanosheets under thermal treatment conditions, demonstrating their robustness and suitability for diverse applications. Furthermore, the research reveals that the choice of silane precursor impacts the stiffness of the resulting SiOx material, opening up opportunities to fine-tune material properties for specific applications.
According to the authors, the scalability of this synthesis method holds immense potential for industrial implementation. Future work could focus on optimizing the production process to meet industrial demands while maintaining the integrity of the nanosheet morphology.
In summary, the research conducted by Dr. Richard Olsson and colleagues at the KTH Royal Institute of Technology in Sweden represents a significant breakthrough in the field of nanomaterials synthesis. Their innovative approach to templating SiOx nanosheets using GO as a template offers a scalable and precise method for producing 2D silicon oxide materials. These materials exhibit exceptional uniformity, large surface area, and durability, making them promising candidates for a wide range of applications across industries.
Birdsong BK, Hoogendoorn BW, Nilsson F, Andersson RL, Capezza AJ, Hedenqvist MS, Farris S, Guerrero A, Olsson RT. Large-scale synthesis of 2D-silica (SiOx) nanosheets using graphene oxide (GO) as a template material. Nanoscale. 2023;15(31):13037-13048. doi: 10.1039/d3nr01048a.