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

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.