Influence of doping Fe on performance of calcium-based doped materials for thermochemical energy storage: A DFT study

In this paper, the optical and thermodynamic properties of Fe-doped Ca-based materials were revealed by the Density Functional Theory method. The results showed that the doped Fe atom was oxidized by O2− to form inert structures, enhancing the resistance of CaO to sintering at high temperatures. More importantly, the doping of Fe enabled the electrons to jump between energy levels more easily, improving the light absorption ability of Ca-based composites. Meanwhile, a qualitative analysis of the thermodynamic parameters of the composites was carried out. It was found that the thermal conductivity and specific heat capacity of the composites decreased with increasing iron content, while the Debye temperature increased. Besides, the doping of Fe leads to the reduction of activation energy of the reaction due to the formation of electron-deficient O sites on the surface, resulting in a suppression of the reaction rate between CaO and CO2.