Water is essential for living organisms and consequently for human beings to sustain life. As the World Health Organisation (WHO) and the United Nations Children's Fund (UNICEF) reports 1,2 indicate, the world, especially in developing countries, is not blessed with the quantity and quality of water necessary for human activity and healthy living. In 2021, over 2 billion people live in water-stressed countries, which is expected to be exacerbated in some regions as a result of climate change and population growth. In 2022, globally, at least 1.7 billion people use a drinking water source contaminated with feces. Microbial contamination of drinking water as a result of contamination with feces poses the greatest risk to the drinking water safety. Prospects of access to clean drinking water are getting grimmer towards mid-century or just one generation away by 2050. Moreover, due to warming climate, the temperature of underground water is increasing rendering it undrinkable by 2100 (3.5 • C increase is predicted) due to higher solubility of toxic contaminants which are kept at safe levels at current global level temperature of 21 • C. As a means of securing water, water supply facilities have been developed in only 49% of developing countries and 12% of least developed countries. In other words, access to the safe-to-drink water is limited. In particular, African and Southeast Asian countries have low coverage of water supply to each household. In this situation, it is important to improve water quality and secure sustainable water sources, as stated in the Goal 6 of the Sustainable Development Goals (SDGs). On the other hand, although water safety and quantity are ensured in Japan, situations arise in which water supply is needed in the event of a disaster such as a major earthquake or flooding caused by heavy rains or typhoons. Under these global conditions of scarcity of drinking water, there is a need for a stable and safe source of water supply. As a solution to this problem, technology that utilizes photothermal conversion of sunlight to produce pure water by distilling used contaminated water or abundant seawater has been attracting increasing attention. Several photoelectric conversion devices have been proposed for high-efficiency water evaporation. Among those devices, use of TiN nanoparticles. TiN nanoparticles (TiN NPs) are selected as lossy plasmonic nanocavities and showed that the solar absorption efficiency of TiN NPs was higher than that of gold and black carbon NPs. Furthermore, by creating a structure in which TiN NPs were chemically fixed with ceramic fiber wool (CFW), it was easy to handle and reuse. The CFW effectively supplied water through capillary forces so that the TiN NPs were always kept close to the water surface. When sunlight illuminates the structure, the TiN NPs absorbed the sunlight, and the CFW suppresses the unnecessary heating of the remaining water. A solar heat conversion efficiency of over 80% was obtained at 100 mW.cm -2 exposure flux.