Spinel Cu-Mn-Cr Oxide Nanoparticle-Pigmented Solar Selective Coatings Maintaining >94% Efficiency at 750 degrees C

Abstract

High-temperature concentrating solar power (CSP) system is capable of harvesting and storing solar energy as heat towards cost-effective dispatchable solar electricity. Solar selective coating is a critical component to boost its efficiency by maximizing solar absorptance and minimizing thermal emittance losses. However, maintaining a high solar-thermal conversion efficiency >90% for long-term operation at >750 degrees C remains a significant challenge. Herein, we report spray-coated spinel Cu-Mn-Cr oxide nanoparticle-pigmented solar selective coatings on Inconel tube sections maintaining >94% efficiency at 750 degrees C and >92.5% at 800 degrees C under 1000x solar concentration after 60 simulated day-night thermal cycles in air, each cycle comprising 12h at 750 degrees C/800 degrees C and 12h cooling to 25 degrees C. The solar spectral selectivity is intrinsic to the band-to-band and d-d transitions of non-stoichiometric spinel Cu-Mn-Cr oxide nanoparticles by balancing the lattice site inversion of Cu2+ and Mn3+ on tetrahedral vs. octahedral sites. This feature offers a large fabrication tolerance in nanoparticle volume fraction and coating thickness, facilitating low-cost and scalable spray-coated high-efficiency solar selective absorbers for high-temperature CSP systems.

This is the orginal version of our paper later published in ACS Applied Materials and Interfaces. Some revisions are made in the final version, which is provided in the DOI and journal reference info