Tailoring europium-doped CuBi2O4 nanorods for enhanced solar steam generation and desalination

Abstract

Freshwater scarcity is a growing global challenge, and solar-driven steam generation offers a promising, eco-friendly solution for desalination and water purification. However, its efficiency is often hindered by poor light absorption, high charge carrier recombination, and thermal losses. To address these limitations, we synthesized europium-doped copper bismuth oxide (Eu-CuBi₂O₄) nanorods using a hydrothermal method, enhancing photothermal conversion efficiency. By integrating these nanorods into a 2D evaporation structure where they were coated onto cotton gauze and insulated with polystyrene foam for better thermal confinement we achieved a highly efficient solar steam generator. Under 1 kW/m² solar illumination, our system demonstrated an outstanding evaporation rate of 2.33 kg/m²⋅h, with an impressive solar-to-vapor conversion efficiency of 96 %, ensuring rapid and effective water evaporation. The system remained stable over 20 continuous cycles, maintaining efficiency without salt accumulation or performance loss. Thermal imaging confirmed that the material retained heat efficiently, reaching surface temperatures of 75.5 °C, further boosting evaporation rates. More importantly, this solar evaporator effectively removed over 95 % of dissolved salts (Na⁺, K⁺, Mg²⁺, Ca²⁺) and organic contaminants like Methylene Blue and Rhodamine B, even when processing high-salinity water up to 20 wt% brine. These results highlight Eu-CuBi₂O₄ nanorods as a powerful and sustainable photothermal material, paving the way for scalable, low-cost solar desalination and water purification technologies to meet the growing demand for clean water worldwide.