Preparation Of Ni₃S₂ Materials And Reserch On The Performance Of Photothermal Conversion

Fresh water is one of the most important material resource for human survival and development.Solar-driven water evaporation technology is a potentially promising method and a feasible and effective fresh water resource production technology.In the new interfacial heating system,the capture of solar energy and the generation of water vapor can be completed at the water-air interface,which greatly improves the efficiency of photothermal conversion.Therefore,it is of great significance to prepare photothermal materials with good properties and apply them to the interface system.Co₃O₄ and Ni₃S₂ are two types of semiconductor materials with low band gap width.Their absorption spectrum covers the UV-V-NIR band,which can capture a large amount of solar energy and have great application potential in the field of photothermal conversion.In this paper,two kinds of semiconductor photothermal conversion materials,Co₃O₄ and Ni₃S₂,were prepared by hydrothermal method on the Ni-foam substrate and applied in the field of interfacial heating,and the basic characterization such as morphology and phase composition and photothermal conversion properties of the materials were studied.The morphologies and properties of the two kinds of materials prepared under different conditions were compared,and the most significant and practical material was obtained and further studied.The effects of hydrothermal time,hydrothermal temperature and reactant content on the morphology,phase composition,light absorption characteristics and photothermal conversion performance of the material were studied.The characteristics of interfacial evaporation process,cycling stability and practical application potential were also studied.The results showed that the Co₃O₄ material prepared on the titanium mesh substrate showed the most excellent surface morphology,and the evaporation rate si the highest in all prepared materials,reaching 1.48 kg·m-2·h-1.However,the bonding strength of the material is poor,which makes it difficult to guarantee the stability of the performance of repeated experiments.However,the Ni₃S₂ material prepared in situ on the Ni-foam substrate has better binding force,and the evaporation rate of the material is close to Co₃O₄ material prepared on the titanium mesh substrate.Moreover,the water evaporation performance can be further improved by optimizing the process conditions,indicating that the material has greater research value and application potential.During the research of the Ni₃S₂ material prepared in situ on the Ni-foam substrate,the hydrothermal time and thiourea content only affect the microstructure of the prepared samples,while the composition are not affected,and the products are all Ni₃S₂.However,the hydrothermal temperature affects both the microscopic morphology and phase composition of the samples.When the temperature is 160?,the product changes into Ni7S6.When the hydrothermal time is 6 h,the hydrothermal temperature is 140?,and the thiourea content is 2.5 g,the surface of the sample shows perfect flower-like structure,and the absorption rate is as high as 93.13%.At the same time,it also shows the highest water evaporation performance and the evaporation rate can reach 1.53 kg·m-2·h-1.The water evaporation rate and photothermal conversion efficiency of the sample in 5 cycles were basically maintained at about 1.5 kg·m-2·h-1 and 84.5%,indicating that the sample has good photothermal stability and reusability.After desalination,the concentration of major ions in the solution decreases to less than 2 mg/L,indicating good practical application potential.