Study on preparation and performance of TiN modified vertically aligned carbon fiber evaporator

The application of solar photothermal conversion is currently one of the main ways to utilize solar energy, therefore it is crucial to find effective materials for photothermal conversion. In this study, carbon fiber evaporators (C-EVAP and R-EVAP) with vertically aligned carbon fiber structure were prepared from ramie and cotton using fiber bundling and carbonization, and then TiN-C-EVAP and TiN-R-EVAP were further obtained by modifying with TiN. The effects of precursor materials and TiN modification on the performance of the evaporators were discussed. The vertically aligned carbon fiber structure facilitates rapid moisture transport similar to the tree stem, enhances the internal reflection of light and improves light absorption. Compared to the short carbon fibers of cotton evaporators, ramie evaporators (R-EVAP and TiN-R-EVAP) with the long vertically aligned carbon fibers and multi-stage hollow structure have better photothermal conversion efficiency. Owing to the wide plasma resonance absorption spectrum and high absorbance of TiN, the TiN modification improves photothermal conversion efficiency of the carbon evaporators. The combination of long vertically aligned carbon fiber structure and TiN modification gives the ramie evaporator efficient photothermal conversion performance. The prepared TiN-R-EVAP has the best photothermal conversion efficiency with an evaporation rate of 1.96 kg·m ⁻²h ⁻¹ and an evaporation efficiency of 91.29 % under 1 sunlight. It also has seawater desalination capability and excellent cycling stability, and the typical ion content of the TiN-R-EVAP desalinated condensate can meet the World Health Organization (WHO) standard for usable freshwater salinity. The vertically aligned ramie evaporators similar to the tree stem can be applied to the fields of photothermal conversion and seawater desalination.