Achieving optically selective coatings of silica fixated carbon nanotubes for solar energy applications
Year: 2024
Type: article
Abstract: Solar collectors have the potential for significant climate change mitigation by substituting heat produced with fossil fuels. To achieve this, collectors with highly efficient solar absorbers are essential. Carbon nanotubes are highly absorbing, sustainable, cheap, and thermally stable, making them a promising material for solar absorbers. However, achieving a high solar absorptance and low thermal emittance (solar selectivity), while maintaining good thermal stability and scalability is challenging. Here, we present a selective coating based on multi-walled carbon nanotubes and silica (SiO2). A water-based dispersion enabled by carboxyl functionalization of the carbon nanotubes (CNTF) is spray coated on a stainless steel (SS) substrate and covered by a sol-gel dip coated silica layer. The SS/CNTF/SiO2 surface exhibits a high solar absorptance and an optical selectivity dependent on the CNTF area load, which improves when exposed to elevated temperatures. The coating also demonstrates excellent thermal stability, with an estimated lifetime of >25 years at working temperatures ≤222°C. All together, we show that by using scalable and cheap technology, concurrent with sustainable materials and a simple structural design, we can manufacture a coating that exhibits properties suitable for low- to mid-temperature applications. Our study thus highlights the potential of carbon-based solar absorbers.
Institutions: Absolicon Solar Collector (Sweden), Umeå University
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,430
OpenAlex ID: W4403351090