| As a clean new energy,solar energy can effectively alleviate the energy shortage and environmental pollution caused by fossil fuels.Due to the special band structure of semiconductor,the utilization of solar energy is possible,which can be used in the fields of photocatalytic degradation,hydrolysis and hydrogen production.Traditional corrosion protection methods mainly include protective coating and sacrificial anode.The sacrificial anode is a common and simple corrosion protection method.However,the sacrificial anode method has some shortcomings,such as short life,can not be reused,so it will consume a lot of anode protection materials.It is a relatively new field of solar energy utilization to use photogenerated electron hole in semiconductor photoelectrochemical process for metal corrosion protection.In this paper,titanium dioxide nanotubes were prepared by anodizing.After hydrothermal loading of strontium titanite,strontium titanite/titanium dioxide composite films were formed.On this basis,a new type of composite film was formed by continuously loading the cocatalyst material.The relationship among microstructure,photoelectrochemical properties and corrosion resistance of the above materials was explored.The conclusion is as follows:(1)The structure of strontium titanite/titanium dioxide nanotubes with maximum photocurrent can be obtain by controlling the conditions that titanium foil was anodized at 40 V for 45 h,the strontium hydroxide solution is 20 mmol/L(2)The corrosion protection performance of the prepared SrTiO3/TiO2 composite film was tested.It is found from Tafel polarization curve that when the area of stainless steel is three times that of photoanode material,the self corrosion potential of stainless steel is-450 mV.With the decrease of stainless steel area,corrosion potential continued to move negative.When the area of stainless steel is one third of the area of photoanode material,the corrosion potential of stainless steel moves from negative to-520 mV.The protection current density of the photoanode material to stainless steel is higher than the minimum protection current required by stainless steel.Under the condition that the contact area between the metal and the liquid surface is constant,it is found that the charge transferred from the photoanode material to the stainless steel is in a positive proportion to the difference between the light and dark equilibrium potentials of the photoanode material at OCP potential.Therefore,the potential difference of OCP in light and dark state can be used as a simple descriptor of the corrosion resistance of photoanode materials.(3)The self-corrosion potential of stainless steel was shifted from-481 mV to-542 mV,compared with that of SrTiO3/TiO2 composite film.The results show that the band gap width of the composite can be reduced and the absorption of visible light can be increased by loading the cocatalyst.At the same time,the cocatalyst with OER activity can promote the separation of photogenerated charge,reduce the recombination of photogenerated electron hole pair,and improve the photoelectric performance and enhance the electrochemical protection of stainless steel.In addition,through the study of the stability of this kind of photoanode material under the condition of long-term dark state(simulating the real environment without sufficient sunlight,such as night),it is found that the load of cobalt hydroxide is a double-edged sword:under the condition of light,it can greatly improve the photoelectrochemical corrosion performance;under the dark state,due to the low equilibrium potential of cobalt hydroxide,the photoanode will be shaped like stainless steel The battery can accelerate the corrosion of stainless steel. |
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