Interfacial solar vapor generation using sawdust hydrochar/titanium dioxide composite as photothermal conversion material

Abstract

Carbon based composite has gained interest as a photothermal conversion material for interfacial solar vapor generation towards the generation of clean water through solar– thermal conversion. In this study, successful synthesis of a carbon/ceramic composite containing sawdust hydrochar (SHC) and titanium dioxide (TiO₂) was obtained through a simple mixing method. The SHC/TiO₂ composite was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), Fourier-Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible spectrophotometry (UV–Vis). SEM showed the simple mixing method only minimally damaged the SHC structure, while TEM revealed the integration of TiO₂ on the surface of SHC. The existence of the TiO₂ elements and various functional groups detected in the EDX, FTIR, and XPS proved the successful integration of TiO₂. UV-Vis displayed the SHC/TiO₂ had improved light absorption ability in contrast to the SHC and TiO₂. The SHC/TiO₂ based solar absorber (SHC/TiO₂–SA) was fabricated using dip-coating method and utilized for interfacial solar vapor generation in seawater desalination. The interfacial solar vapor generation was conducted outdoors with an average solar intensity of 1.15 kW/m² where the SHC/TiO₂–SA showed the highest average efficiency (76.3 ± 4.6%) and evaporation rate (1.29 ± 0.15 kg/m².h). While the salinity (180 ppm) and pH (6.97) of the collected clean water was within the World Health Organization drinking water standard.