Enhanced and Selective Absorption of Molybdenum Nanostructured Surfaces for Concentrated Solar Energy Applications

Year: 2022

Authors: Santagata Antonio; Pace Maria Lucia; Bellucci Alessandro; Mastellone Matteo; Bolli Eleonora; Valentini Veronica; Orlando Stefano; Sani Elisa; Failla Simone; Sciti Diletta; Trucchi Daniele Maria

Autors Affiliation: Zona Industriale, FemtoLAB, UOS Tito Scalo, CNR ISM, I-85050 Tito, Italy: UOS Montelibretti, DiaTHEMA Lab, CNR ISM, Via Salaria Km 29-300, I-00015 Monterotondo, Italy; CNR INO, Largo Enr Fermi 6, I-50125 Florence, Italy: CNR ISTEC, Via Granarolo 64, I-48018 Faenza, Italy

Abstract: Surfaces of commercial molybdenum (Mo) plates have been textured by fs-laser treatments with the aim to form low-cost and efficient solar absorbers and substrates for thermionic cathodes in Concentrated Solar Power conversion devices. Morphological (SEM and AFM), optical (spectrophotometry), and structural (Raman spectroscopy) properties of the samples treated at different laser fluences (from 1.8 to 14 J/cm(2)) have been characterized after the laser treatments and also following long thermal annealing for simulating the operating conditions of thermionic converters. A significant improvement of the solar absorptance and selectivity, with a maximum value of about four times higher than the pristine sample at a temperature of 800 K, has been detected for sample surfaces treated at intermediate fluences. The effects observed have been related to the light trapping capability of the laser-induced nanotexturing, whereas a low selectivity, together with a high absorptance, could be revealed when the highest laser fluence was employed due to a significant presence of oxide species. The ageing process confirms the performance improvement shown when treated samples are used as solar absorbers, even though, due to chemical modification occurring at the surface, a decrease of the solar absorptance takes place. Interestingly, the sample showing the highest quantity of oxides preserves more efficiently the laser texturing. The observation of this behaviour allows to extend the applicability of the laser treatments since, by further nanostructuring of the Mo oxides, it could be beneficial also for sensing applications.

Journal/Review: MATERIALS (BASEL)

Volume: 15 (23)      Pages from: 8333-1  to: 8333-20

KeyWords: solar absorbers; nanotexturing; ultra-short laser pulses; concentrated solar power; solar selectivity; thermionic converters
DOI: 10.3390/ma15238333