Mechanically Robust and Flame-Retardant Silicon Aerogel Elastomers for Thermal Insulation and Efficient Solar Steam Generation

Abstract

In this work, we report the synthesis of silicon aerogel elastomers (SAEs) by one-pot hydrolytic condensation of silanes, followed by drying at room temperature. The as-synthesized SAE features excellent flexibility and mechanical robustness, for example, a high compressive strength of up to 40 kPa at 75% strain was achieved. Combined with their thermal insulation properties (a low thermal conductivity of ca. 0.02 W m −1 K −1 in air), for the first time, such SAEs were used as a porous platform for both flame-retardant measurement and solar steam generation. By coating with Mg(OH) 2 via a facile coprecipitation method, the treated SAEs show excellent flame retardancy with a peak heat release rate of 25.61 kW m −2 , in addition to high fire resistance and excellent smoke suppression. When used as a solar steam generator, their evaporation efficiency was measured to be 82.7% (1 kW m −2 ), which could compete with that of other high-performance bilayered photothermal materials reported so far. Taking advantage of their simple and cost-efficient manufacture and superior mechanical robustness and flexibility, such SAEs with multifunctionalities may have great potential for a wide variety of energy-saving applications, for example, especially for thermal insulation coatings with better flame retardancy and efficient solar steam generation for desalination or freshwater production.

Versatile Direct Writing of Aerogel-Based Sol–Gel Inks

“…To assess the water evaporation performances of 3D-printed CAs and bulk CA, the evaporation efficiency was calculated by the ratio of the harvested energy to the total solar energy based on the previous method. ,, Bulk CA, 3D-printed CA-1, and 3D-printed CA-2 had evaporation efficiencies of ∼69.82, ∼84.48, and ∼88.38%, respectively (∼15.15% for pure water). The significantly high evaporation rate (>1.4 kg m –2 h –1 ) and efficiency (>84%) of 3D-printed CAs for solar steam generation had a relatively considerable magnitude among the research work of recent years under 1 sun illumination (Figure f). ,− Thus, there is plenty of space to achieve a higher evaporation rate and evaporation efficiency using DIW to purposefully stack 3D structures, demonstrating the versatility and flexibility of DIW in the production of high-efficiency evaporators.…”

Aerogels in passive solar thermal desalination: a review

“…Silicon aerogel elastomers (SAEs) with excellent flexibility and mechanical robustness are other potential candidates for the efficient solar steam generation process. 73 SAEs were synthesized via a facile one-pot reaction, and their top surfaces were treated with magnesium hydroxide as a flame-retardant coating layer. These SAEs showed a high compressive strength of 40 kPa at 75% strain and low thermal conductivity of 0.02 W m −1 K −1 .…”

Recent Progress on the Solar‐Driven Interfacial Evaporation Based on Natural Products and Synthetic Polymers

“…Sun and colleagues [ 158 ] reported layered Ag–PSS–Ag/AG, which was obtained by modifying the agarose gel (AG) with silver NPs and sodium PSS ( Figure a). The evaporation rate of Ag–PSS–Ag/AG was 2.10 kg m −2 h −1 and solar thermal efficiency was 92.8% under 1 sun irradiation.…”