Efficient solar-thermal energy conversion with surfactant-free Cu-oxide nanofluids

High-specification nanofluids can potentially enable cost-effective and highly efficient solar-to-thermal energy conversion. However, their implementation is adversely affected by poor absorption spectral range and stability challenges of the nanoparticles. Here we demonstrate the synthesis, full characterization and application of Cu -oxide nanoparticles with high optical absorption and long-term stability over many months. The synthesis method, based on a hybrid plasma-liquid non-equilibrium electrochemical process, ensures a very limited environmental impact as it relies on a solid metal precursor while avoiding the use of additional chemicals such as surfactants and other reducing agents. We further investigate the fundamental links between the nanofluid performance and the material and optical properties and produce a theoretical model to determine the energy conversion efficiency. The results show that nanofluids produced with our Cu-oxide nanoparticles can achieve exceptional solar thermal conversion efficiencies close to similar to 90% and can provide a viable solution for an efficient solar thermal conversion technology.

Automated summary

High-specification Cu-oxide nanoparticles with high optical absorption and long-term stability have been synthesized and characterized for efficient solar-to-thermal energy conversion. The synthesis method based on a hybrid plasma-liquid non-equilibrium electrochemical process has limited environmental impact and avoids the use of additional chemicals. Investigation of the nanofluid performance and optical properties has led to the development of a theoretical model to determine the energy conversion efficiency. The results show that nanofluids produced with the Cu-oxide nanoparticles can achieve exceptional solar thermal conversion efficiencies close to 90%.