MnFe2O4 and MnO2 nanoparticle-based high-temperature, air-stable, long-term antioxidation cermet solar selective absorbers

Abstract

Concentrated solar power (CSP) systems need to complement the photovoltaic (PV) technology via energy storage to better integrate solar electricity in to power grids. The efficiency of CSP systems can improve with high optical absorption in the solar spectrum regime and low emittance in the infrared (IR) spectrum, thereby reaching higher operation temperatures for lower levelized cost of energy. High-temperature, air-stable solar selective absorbers made with cermet composite materials that have optimal properties of both ceramic and metal can be the solution to this goal; however, this achievement has been difficult due to metal oxidation at high temperatures. Current state-of-the-art product such as the Pyromark 2500 black paint has a significantly high solar absorbance (α solar =97%) in the solar spectrum regime but also has a high thermal emittance loss (e=88%) in the IR spectrum at 750 °C.[1] Here, we demonstrate outstanding optical responses of thermodynamically-stable, high-temperature, low-cost long-term antioxidation cermet solar selective absorber coatings with MnFe 2 O 4 and MnO 2 nanoparticles and silicone precursors as Si-rich matrices that undergo inter-diffusion reaction with Stainless Steel 310 (SS310). It has been shown that absorbers with MnFe 2 O 4 nanoparticles have solar absorbance of ~92.5%, thermal emittance of 55%, and thermal efficiency of 88-89% posterior to annealing at 750°C for 700 hours in air, and those with MnO 2 nanoparticles have solar absorbance of ~91.5%, thermal emittance of 52.5%, and thermal efficiency of 88% posterior to annealing at 750°C for 700 hours in air. We expect that the solar selective absorber coatings with such high thermal efficiencies and high-temperature stability in air will lead to a breakthrough in the market of CSP systems.