Sonication enabled liquid marble frameworks: synthesis, characterizations and applications
Creators: name: Zhang, Wei
Publisher: name: RMIT University
Year: 2024

description: The ‘liquid marble frameworks’ which are made of micro– to nano–sized liquid marbles are developed using sonication. It is shown that the size, the surface chemical/physical compositions and the order of coating of the developed liquid marbles can be tuned. To obtain various functionalities, different types of liquid cores and coatings are utilized to develop liquid marble frameworks made of micro– to nano–sized coated spheres using. The synthesized frameworks provide enhanced performance for heavy metal ion sensing, photocatalysis, hydrogen gas sensing and surface enhanced Raman scattering (SERS). The work is conducted in four distinct stages. <br><br>In the first stage, liquid metal/metal oxide (LM/MO) frameworks are developed by sonicating liquid metal galinstan. <br>The developed frameworks are characterized. It is found that their surface morphology and chemical composition are functions of the sonication duration. The LM/MO framework, made with sonication duration of 20 min show enhanced photocatalytic efficiency of ~47 % h–1. WO3 nanoparticles are incorporated to LM/MO frameworks to obtain high sensitivity towards low concentrations of heavy metal ions. The sensitivity towards Pb2+ as low as 100 ppb is obtained, which is about 80 times improvement compared to bulk liquid marbles. The detection limit is lower than the hazardous thresholds of heavy metal ions for humans.<br><br> In the second stage, gallium oxide (Ga2O3) is synthesized using a solvothermal method. The synthesized Ga2O3 are incorporated to the LM/MO frameworks to realize enhanced photocatalytic systems. The surface stoichiometry of these systems can be tuned by changing the loading of incorporated Ga2O3 nanoparticles. With 1 wt% loading of incorporated Ga2O3, the photocatalytic efficiency of the systems is ∼100 % h−1, which is much higher than the efficiency of either LM/MO frameworks or pure Ga2O3.<br><br> In the third stage, WO3 nanoparticles are incorporated to liquid metal (LM) frameworks in order to form liquid metal/tungsten oxide (LM/TO) hydrogen (H2) gas sensors. The results of characterization shows that the incorporated WO3 nanoparticles are partially reduced when incorporated to the surface of liquid metal cores. The optimum operating temperature for the LM/TO sensor is found to be 200 ºC. At this temperature, the response time of the LM/TO sensor towards 1% H2 at is 90 s, which is approximately 2.5 times faster than H2 gas sensors based solely on WO3 nanoparticles. The LM/TO H2 gas sensors also show excellent reproducibility when exposed to increasing concentrations of H2 gas. In the final stage, silver (Ag) nanoparticle/oleic acid liquid marble frameworks are developed by encapsulating Ag nanoparticles to micro–sized oleic acid liquid spheres, which is achieved via sonication.<br><br> Optimum order of Ag nanoparticle coating can be obtained when the frameworks are sonicated for 60 min. The SERS responses of frameworks towards an organic thiolate are measured. The frameworks with sonication of 60 min show the strongest response. Efficient solar energy absorption of the frameworks is also demonstrated. Results show that frameworks with sonication of 60 min experience the largest temperature rise (11.8 ºC) after being illuminated under a simulated solar source for 30 min.<br><br>