Graphene aerogel is a sponge-like material composed of a three-dimensional graphene network. This new type of porous material has huge technological prospects. Its unique potential is based on combining the nanoscale properties of exfoliated graphene with the adjustable macroscopic properties of aerogel materials, including controllable porosity, large surface area, flexible mechanical properties and ultra-low density. Therefore, graphene-based aerogels have been successfully applied in a series of technologies, including environmental remediation, structural composite materials, biological materials, electronics, sensors, energy storage and other fields. In addition, the composite of inorganic nanoparticles into graphene aerogels is expected to greatly improve the performance of aerogels in the prior art. Recently, graphene-based aerogel composite hydrotalcite-like compounds have undergone many studies and have considerable application prospects. Hydrotalcite-like compounds, also known as layered double hydroxide (LDH), are layered anionic clays containing divalent and trivalent metal ions. Due to its flexible chemical composition and excellent atomic metal dispersion, LDH particles are ideal precursors for functional inorganic nanoparticles.
Robert Menzel of the University of Leeds and Diana Iruretagoyena of the Imperial College of Technology in the United Kingdom reported that graphene oxide (rGO) aerogels are hydrotalcite-derived nanoparticles (MgAl-Mixed Metal Oxide MgAl) in two important commercial adsorption applications. -MMO) provides a highly stable multifunctional porous carrier. Compared with the unsupported nanoparticle powder, the aerogel-supported MgAl-MMO nanoparticle exhibits a significant enhancement in adsorption and desulfurization performance, and the organic sulfur absorption capacity increases by more than 100%. In addition, the CO2 adsorption performance of the composite aerogel was evaluated under high temperature and high CO2 pressure. Its total CO2 capacity is more than twice that of unsupported nanoparticles, reaching 2.36 mmol·CO2 g−1 ads, which is better than other high pressure CO2 Adsorbent. The research was published on "Advanced Functional Materials" as a paper entitled "Electrically Heatable Graphene Aerogels as Nanoparticle Supports in Adsorptive Desulfurization and High-Pressure CO2 Capture".
In order to load nanoparticles on high-load rGO aerogels, the authors prepared composite aerogels by the LDH-modified GO polymer-assisted wet chemical assembly method. The aerogel is synthesized in three stages (Figure 1). In the first stage, the pre-synthesized LDH particles are thoroughly dispersed in the GO/polymer aqueous solution, and the positively charged LDH nanoparticles are adsorbed onto the negatively charged GO sheets through electrostatic interaction, thereby forming LDH-modified GO nanosheets in the solution. Then the aqueous solution is poured into a cylindrical mold, with the help of polymer additives, LDH/GO hydrogel is formed. In the second stage, the LDH/GO hydrogel is unidirectionally frozen to obtain the large pores in the aerogel. In the third stage, the sample is annealed at a high temperature in a reducing atmosphere to obtain the final composite aerogel. Annealing treatment can remove polymer additives, promote covalent crosslinking, and enhance the structural stability of hybrid aerogels. In addition, the annealing treatment can also restore the graphite crystallinity of the nano-carbon framework, so that the final composite aerogel adsorbent has conductivity, so electric heating can be realized.
Summary: The author reported a simple method to support metal oxides and metal nanoparticles on a porous rGO aerogel carrier with a loading capacity of up to 20% through the polymer-assisted assembly of LDH-modified GO nanosheets. In this study, LDH-derived nanoparticles are loaded in macroporous aerogels, which can significantly improve its organic sulfur adsorption properties. At the same time, the aerogel adsorbent has excellent CO2 adsorption capacity, up to 2.36 mmol CO2 g-1 ads. The excellent performance of the aerogel-loaded MgAl-MMO in two independent adsorption applications clearly proves that rGO aerogel has excellent stable support function. The reliable loading of LDH-derived nanoparticles on GO aerogel effectively suppresses the damage and deactivation of nanoparticles during the use and regeneration of the adsorbent.
Original link:
https://onlinelibrary.wiley.com/doi/10.1002/adfm.202002788