Plasmonic group IV transition metal carbide interfaces for solar-driven desalination

Abstract

To combat the dwindling supply of freshwater, solar-driven desalination using plasmonic nanomaterials has emerged as a promising and renewable solution. Effective materials must exhibit high solar-to-vapor conversion efficiencies, be inexpensive, chemically stable, and maintain performance over time. Refractory plasmonic carbide nanomaterials are exciting candidates that could meet these demands but have not been as widely explored. Here, we investigate plasmonic carbide interfaces made of TiC, ZrC, and HfC nanoparticles loaded onto to a mixed cellulose ester (MCE) membrane gain insight into their solar-vapor generation and desalination potential. Evaporation rates and efficiencies were determined for tap water and saltwater with varying salt concentrations. Desalination using Atlantic Ocean water under 1 sun intensity yielded rates of 1.26 ± 0.01, 1.18 ± 0.02, and 1.40 ± 0.01 kg m-2 h-1, with efficiencies of 86, 80, and 96% for TiC, ZrC, and HfC, respectively, under 1 sun illumination. Carbide interfaces effectively removed salt and metal ions from the water and were able to reject salt over extended periods of desalination and high salt concentrations of up to 35%. The effect of ambient temperature and relative humidity on the desalination process was also investigated which showed that the evaporation rates and efficiencies decrease with increasing humidity and decreasing room temperature. However, the performance of HfC was less affected by the changes in the ambient conditions compared to TiC and ZrC.