Optical nanofluids for direct absorption-based solar-thermal energy harvesting at medium-to-high temperatures

Direct absorption-based solar collectors, which rely on volumetric absorption of sunlight by optical nanofluids, have emerged as a superior way to conventional surface absorption-based collectors for harvesting solar-thermal energy. In this short review, we summarize the recent progress on preparing medium-to-high-temperature solar-thermal nanofluids that can be potentially used in direct absorption-based solar collectors under concentrated solar fluxes. Emphasis is placed on discussing the challenge and strategies to achieve stable dispersion of the optical nanofluids.