Nanoarray Materials:surface Regulation And Electrochemical Properties

With the developments of society and economy,the demands of clean energy and technology are in hurry.Some new cleaned and cycled energies have been put into use,such as solar energy,tidal energy,wind energy,biogas et al.Hydrogen energy has been considered as the most potentials clean energy due to its pollution-free during the producing or using periods.Another candidate is the metal-air battery which use air as fuel and no pollution during electric generation progress.The aim of this paper is to develop the hydrogen energy and metal-air battery with high efficiency and low energy consumption.One more thing is two electrode reactions of the overall watersplitting system and cathodic reaction of metal-air battery during charging and discharging progress are gas involving reactions.To develop the performance of gas-involving electrochemical reactions,two ways should be paid in attention.First,we should develop some new and efficiency materials as catalysts.Then,we should also pay some attentions on restructuring the structure and surface morphology.The regulation of surface wettability of electrode surface can improve gas leaving and adsorption behavior.Both of the two electrode reactions are gas evolution reactions,the nano structured electrode can promote gas production leave the surface as soon as possible.While for the metal-air battery,two different reactions are included during charge and discharge process.During the discharge process,a superaerophilic surface can accelerate the oxygen adsorption rate,while for the charge process,a superaerophobic surface is better to promote the gas bubble release from the surface.Herein,we synthesized and regulated some nanoarrays materials as the electrode for overall water splitting system and the metal-air battery to improve the efficiency of the systems.The research contents and conclusions are shown as following:1.We developed an overall watersplitting system with the superaerophobic nanostructures materials as the electrodes,which showed ultrahigh current density(400 mA cm-2),and a quite stable for 100 hours.For the OER side,we synthesized the nanostructured NiFe-LDH by a hydrothermal method,and the size of oxygen bubble leaving the surface was only 29 ?m.For the HER side,we developed an electroplating method to construct a NiMo-alloy on Cu foam which showed a superaerophobic surface.The size of hydrogen bubble leaving this surface was only 25 ?m.2.We developed a hydrothermal method to construct the nanowired arrays of cobalt hydroxide on nickel foam substrate.The Ni-Co-O@Ni-Co-S nanoarrays was synthesized by soaked in NaS2 solution.We assumed that nickel and cobalt were considered to be the active sites for OER,but S doped with hydroxides or oxides can improve the activity of OER by affecting the electronic structure.After the vulcanization,the material showed an outstanding OER performance in alkaline electrolyte due to more surface area and active sites,also the coordination of doped S.The sulfide electrode material reduced the OER overpotential by 50 mV.In the long-term running,the sulfide electrode also maintained more than 95%stability at the current density of 200 mA cm-2.3.We developed a carbon nanotubes arrays on carbon fiber paper with a superaerophilic surface by a multi-step method.The cobalt hydroxide nanosheets array were grown as the precursors and catalysts for carbonization.Melamine was used as nitrogen and carbon source and after calcined at high temperature,the cobalt and nitrogen doped carbon nanotubes were synthesized.After the modification of PTFE,the surface of this electrode became superaerophilic.The superaerophilic electrode showed an outstanding ORR performance in alkaline solution and the current density was 200 mA cm-2.We believed this was benefit from its superaerophilic surface.4.On consideration of two different reactions occurred in charging and discharging process,we developed a rechargeable zinc-air battery with three electrodes in high concentration alkaline solution.For the charging process,we chose superaerophobic NiFe nanoarrays as the cathode,on which the oxygen bubbles left the surface in small size.While for discharging process,we developed the superaerophilic carbon nanotubes arrays as the cathode which can supply the sufficient oxygen for ORR.The three electrodes rechargeable zinc air battery reached power density of 250 mW cm-2,and showed a good stability after a 100 cycles running.