Preparation And Properties Research Of Superhydrophobic Rhodium Films On Metal Substrates

In recent years,a variety of functional materials based on bionics research developed rapidly in various fields.Inspired by lotus leaf,water strider,butterfly wings in nature,artificial superhydrophobic materials have attracted wide attention of scientists.Superhydrophobicity is a kind of solid surface wettability,which determined by the morphology and surface chemical composition of the solid surface.Due to its unique properties,superhydrophobic surface has broad application in people's daily life and industrial and agricultural production.At present,there are many methods of fabricating superhydrophobic surface,but most of them are complex,and need harsh conditions.As a member of the platinum group metals,rhodium metal has good catalytic activity,which can catalyze a variety of reactions,but the report of the catalytic performance of the superhydrophobic materials is very little.we obtained Rh-ZnO/Zn and Rh/Cu superhydrophobic surface via chemical displacement and simple electrochemical deposition,annealing treatment without any organic low surface energy materials modification on zinc substrate and copper substrate respectively.The catalytic property of Rh-ZnO/Zn superhydrophobic surface was studied.The main results are as follows:?1?On the zinc substrate,we fabricated micro/nano Rh-ZnO/Zn superhydrophobic surfaces by chemical replacement and followed by thermal annealing.These surfaces display water contact angles?CA?of 171°and sliding angles?SA?of 0°.A series of influencing factors should be considered to prepare optimized superhydrophobic surfaces.These include etching time,the concentration of RhCl₃,the concentration of HCl,annealing time and annealing temperature.The annealing treatment is the most critical factor,which lead the transformation from hydrophilic state to superhydrophobic state.The morphology and chemical composition of the resulting surfaces were characterized using scanning electron microscopy,X-ray diffraction pattern,and energy-dispersive spectroscopy analysis.Then the principle and the growth mechanism of Rh-ZnO/Zn micro-nano superhydrophobic were studied.In order to evaluate the catalytic performance of the prepared rhodium superhydrophobic materials,the reduction of PNP to PAP was chosen as a model reaction in the presence of sodium borohydride aqueous solution.The Rh-ZnO/Zn superhydrophobic surfaces not only showed good catalytic activity but also exhibited excellent reusability.Through the corrosion test,they showed good corrosion resistance.?2?On the copper substrate,we fabricated micro/nano Rh/Cu superhydrophobic surfaces by electrodeposition and followed by thermal annealing.These surfaces display water contact angles?CA?of 168°and sliding angles?SA?of 0°.The factors that may affect the hydrophobicity of the copper coating and how they work were studied with a series of experiments,including etching time,concentration of aqueous solution,reaction time,anneal temperature and anneal time.The hydrophobicity,surface morphologies and chemical compositions of the as-prepared surfaces were investigated using contact angle meter,scanning electron microscope and X-ray diffractometer.The Rh/Cu superhydrophobic surfaces showed self-cleaning property.