Solar Driven Water Evaporation Based On Titanium Dioxide Nanosheets

With economic growth and increased energy demand,solar energy presents opportunities for sustainable development around the world.The vigorous development of interface solar-driven water evaporation technology has made it widely used in steam power generation,seawater desalination,and sewage purification.At present,there are three main influencing factors in this technology:improving the light absorption of solar evaporation systems,reducing heat loss,and optimizing water supply.Titanium dioxide,as a semiconductor material,has been widely used in the field of photocatalysis due to its low cost,stable physical and chemical properties,and environmental friendliness.However,the application of solar driven water evaporation is still lacking,and its potential has yet to be tapped.Therefore,titanium dioxide nanosheets were prepared and modified in this study to further explore potential of TiO₂nanosheet in the application water evaporation of IISDWE on water purification.The main research contents and conclusions are as follows:（1）Ultrathin TiO₂ nanosheet films were prepared on the surface of titanium sheets by hydrothermal method.Compared with the titania films obtained by direct calcination,it had enhanced light-harvesting ability and water-conducting ability.Under one solar intensity,compared with the evaporation rate of 0.58 kg·m^-2·h^-1of directly calcined titanium dioxide film,the evaporation rate of titanium dioxide nano film is 1.09 kg·m^-2·h^-1.The reason was mainly due to the excellent solar light-harvesting ability,water conductivity,and increased specific surface area of TiO₂ nanosheet films.（2）C,N co-doped TiO₂ nanosheet films were prepared in an aqueous solution containing methionine by hydrothermal method.Compared with pure TiO₂ nanosheet films,the C,N co-doped films showed excellent light absorption ability.Molecular dynamics simulation calculations and thermal analysis results also showed that the water evaporation enthalpy on the surface of TiO₂ nanosheets decreases after C,N co-doping.Benefiting from the enhanced solar light absorption capacity and reduced water evaporation enthalpy,the C,N co-doped TiO₂nanosheets achieved a water evaporation rate of 1.57 kg·m^-2·h^-1 and a solar-to-vapor conversion efficiency of 72%.At the same time,the C,N co-doped TiO₂ nanosheets had a good photocatalytic ability,and the degradation rate reached about 40%.（3）TiH₂ composite TiO₂ nanosheets were prepared by hydrothermal method using Ti/TiH₂powder as the precursor.Compared with TiO₂ nanosheets,TiH₂ composite TiO₂ nanosheets had stronger solar light absorption and photothermal conversion performance.Compared with TiH₂,the TiH₂-complexed TiO₂ nanosheets had excellent hydrophilicity,which can provide sufficient water for solar-driven water evaporation.The results of the solar-driven water evaporation test showed that the water evaporation rate of TiH₂ composite TiO₂ nanosheets reached 1.68 kg·m^-2·h^-1,which was higher than 1.54 kg·m^-2·h^-1 of TiH₂ and 1.07 kg·m^-2·h^-1 of TiO₂.