Tunable broadband absorbers with ultra-high thermal emissivity for the MXene/Ti-based Metamaterial

Solar energy was widely used in lots of fields, such as the heat pump technology, seawater desalination, wastewater treatment and photoelectric detection, where efficient use of solar energy was always the goal pursued by mankind. In the work, we proposed a simple and efficient MXene/Ti-based metamaterial absorber and investigated the optical and thermal radiation properties by using the finite-difference time-domain (FDTD) method. The results showed that the average absorption of the MXene/Ti-based metamaterial absorber was higher than 97.6% from 400 nm to 1600 nm, the maximum absorption reached 99.6%, and the solar spectrum weighted absorption was close to 98.5%, and the physical mechanism of the broadband absorption was also explored by theoretical analysis. Compared with the latest reported absorbers, the MXene/Ti-based metamaterial not only had the advantages of low energy loss, high efficiency, and good thermal stability, but also its broadband absorption showed excellent robustness to structural parameters. Moreover, a 75° wide-angle absorption was obtained for the MXene/Ti-based metamaterial, which was independent of polarization. Last but not least, the MXene/Ti-based metamaterial achieved an ultra-high thermal emissivity of 98.3 % at 1600 K, which matched the blackbody radiation curves at 1600 K. These studies had significant implications for catalysis, solar photovoltaics, photovoltaic conversion and other fields.