Comparative study of photothermal conversion efficiency of laser-ablated Ag, Au, and CuO nanoparticles for solar steam generation applications

Due to freshwater scarcity, the urgent need for affordable, effective, and scalable seawater and wastewater purification technologies has gained significant attention. Solar steam generation (SSG) presents a sustainable solution for freshwater production. Noble metal nanoparticles showed higher photothermal conversion efficiencies than conventional materials, drawing considerable interest in SSG applications. In this study, silver (Ag), gold (Au), and copper oxide (CuO) nanoparticles were synthesized using a one-step, environmentally friendly technique called laser ablation in liquid. The impact of varying the laser average power on nanoparticle size, concentration, and photothermal activity were studied. The nanofluids were then applied to SSG, and their evaporation rates were evaluated in comparison to pure water. Under the same 1-sun irradiation circumstances, Au NPs exhibited the highest evaporation rate, achieving 2.29 times the rate of pure water with the highest photothermal efficiency among other prepared nanofluid that reach 80 %. Ag NPs demonstrated an evaporation rate 2.08 times higher, while CuO NPs increased the evaporation rate by 1.73 times compared to pure water. While silver nanofluid photothermal conversion efficiency (PTE) enhancement was 243 % and copper oxide PTE enhancement was 190 %, the optimal performances were achieved with gold nanofluids, exhibiting a (PTE) enhancement of 306 % relative to the base fluid. These results highlight the superior performance of Au NPs in photothermal applications and underscore the potential of metal and metal oxide nanoparticles in developing pure water production by solar energy.