Titanium Dioxide Nanotubes/Electricity-Assisted Application Of Titanium Mesh In Photothermal Water Evaporation

The shortage of fresh water is an urgent problem for human society to solve.With the development of sustainable energy,photothermal water evaporation as a fresh water production technology has attracted wide attention.Efficient evaporation rate and stable structure are the key to the application of photothermal water evaporation technology in practical production and life.Compared with carbon and polymer materials,the mechanical properties of metal materials are stable,and the structure is not easy to be destroyed by external impact.Titanium is the ninth most abundant element on Earth,and the titanium has strong corrosion resistance in seawater.Titanium dioxide（TiO₂）can be widely used in photothermal water evaporation technology because of its low cost,stable physical and chemical properties and environmentally friendly characteristics.In this work,TiO₂nanotube films were prepared on the surface of titanium mesh,and the photothermal water evaporation performance of TiO₂nanotube supported on the surface of titanium mesh was studied.The application potential of photothermal water evaporation of titanium mesh supported by TiO₂nanotubes with electrical assistance was further explored.The work content and conclusions are as follows:（1）TiO₂nanotube films were generated on the surface of titanium mesh by anodic oxidation method.Compared with directly calcined and pure titanium mesh samples,the titanium mesh loaded with TiO₂nanotube thin film on the surface has better light absorption ability and hydrophilicity,and the evaporation enthalpy of water is reduced.The experimental results of photothermal water evaporation show that under simulated solar light intensity of1.0 k W·m^-2,the photothermal water evaporation rate of titanium mesh loaded with TiO₂nanotube film on the surface is 1.98 kg·m^-2·h^-1,which is 65%and 50%higher than that of pure titanium mesh and calcined titanium mesh,respectively.（2）Apply a direct DC voltage of 0～1.2 V to the titanium mesh with TiO₂nanotube film.As the voltage increases,the photothermal water evaporation rate increases gradually.The water evaporation rate is the highest at 1.2 V,reaching 2.48 kg·m^-2·h^-1.The electrothermal effect and internal electric field are the main factors to improve the rate of photothermal water evaporation.On the one hand,the electrothermal effect caused by applied voltage can promote water evaporation.At the same time,because of the semiconductor properties of TiO₂,solar irradiation can reduce the resistance of TiO₂,enhance its electrothermal effect,and generate more heat for water evaporation.On the other hand,under the action of internal electric field,the enthalpy of evaporation of water decreases.The internal electric field also leads to self-doping of TiO₂,which improves the optical absorption ability of the sample and reduces the enthalpy of evaporation of water.In addition,the applied voltage also improves the salt resistance of titanium mesh loaded TiO₂nanotube thin films.