Tuning the Electrical and Solar Thermal Heating Efficiencies of Nanocarbon Aerogels

Abstract

Nanocarbon aerogels display outstanding electrical and solar-thermal heating efficiencies. However, little is known about the relationship between their microstructure and the heating performance. In this study, two different types of carbon nanotube (CNT) aerogels were synthesized via an ice-templating (IT) and emulsion-templating (ET) approach, respectively, which induces drastic difference in internal microstructures, crosslinking densities and porosities. These structural differences give rise to substantial efficiency differences in electrical aerogel heating (e.g. 46 o C/W for rET-CNT aerogel, 75 o C/W for rIT-CNT aerogel). Systematic comparison of nanocarbon aerogel microstructure in terms of nanocarbon type, envelope density, and nanocarbon graphiticity shows that the Joule-heating efficiency is highly correlated with the thermal conductivities of the aerogels, where aerogels with lower thermal conductivities exhibit higher Joule-heating efficiencies. This relationship is also observed for solar-thermal aerogel heating, with the aerogels of lowest thermal conductivity (rIT-CNT aerogel) exhibiting a 30% higher efficiency in solar water evaporation, compared to rET-CNT aerogels. These results demonstrate that the heating properties of nanocarbon aerogels can be readily tuned and enhanced through structural control alone. The findings provide a new perspective for the design of nanocarbon aerogel for applications that involve electrical or solar-thermal heating, such as temperature-dependent separation, sorption, sensing, and catalysis.

Light-induced levitation of ultralight carbon aerogels via temperature control

“…CNTs also absorb a range of wavelengths of sunlight, and research on the use of sunlight on CNT aerogels is currently underway 17 . The ultralight aerogel fabricated in this study can be levitated using actual sunlight (see Supplementary Video S4 online).…”

“…Owing to their high electrical, thermal, and mechanical properties, carbon aerogels have been studied for use in many applications 10 – 16 . Recently, research has also been conducted on the utilization of the light absorption and heating properties of such materials 17 .…”

Recent advances in structural regulation and optimization of high-performance solar-driven interfacial evaporation systems

“…Furthermore, the effects of ice-templating and emulsion-templating methods on the pore structure of CNT aerogels were studied in comparison. 195 The ice-templating CNT (rIT-CNT) aerogel exhibited a highly interconnected 3D network with pores originating from interstitial spaces of the entangled CNTs with an average pore size of ∼0.1 μm, while the network of emulsion-templating CNT (rET-CNT) aerogel had a lower cross-linking density and consisted of loose CNT microspheres with open gaps and channels with an average size of ∼5.6 μm (Fig. 8b).…”

Aerogels in passive solar thermal desalination: a review

“…In this review, we assessed the applicability and overall performance of several engineered aerogels in producing pure water using solar steam generation systems. , (d) 47 , (e) 48 , (f) 49 , (g) 50 , (h) 51 , (i) 52 , (j) 53 , (k) 54 , and (l) 55 .…”

“…2 Summary of a dozen recently published papers with corresponding evaporation rate (ER) values. The references are (a) 45 , (b) 37 , (c) 46 , (d)47 , (e)48 , (f) 49 , (g) 50 , (h) 51 , (i)52 , (j) 53 , (k)54 , and (l)55 .…”