The Preparation Of Solar Light-responsive TiO₂ Film Electrode And Its Hydrogen Production Performance

With the shortage of traditional energy sources and the environmental pollution caused by combustion.Solar energy and hydrogen energy have the advantages of large reserves,clean,renewable and so on.Seeking to use solar energy to catalyze hydrogen production to solve environmental and energy problems is attracting more and more attention.In recent years,more and more research on the catalyst photolysis of water,but due to the performance limit of the catalyst,its practical application is also narrow,with low band,high surface area,has the important significance of TiO2 photocatalysts with high catalytic activity.In this study,graphene and magnesium nitrate are used for TiO2 prepared electrolyte.The process of element doping and composite modification and the self growth of TiO2 in the anodic oxidation process.Short time anodic oxidation at room temperature.A kind of TiO2 composite film electrode doped with graphene and N element can be prepared by in situ growth of titanium substrate.The electrode has a strong optical absorption in the range of 200-2500 nm,and exhibits higher photocatalytic performance under UV light and sunlight.The effects of electrolyte composition,oxidation voltage,oxidation time and calcination conditions on the morphology,hydrogen production and electrochemical properties were studied.The main achievements are as follows:(1)Preparation and characterization of solar light responsive TiO2 film electrodeThrough the systematic study of anodic voltage,oxidation time,electrolyte composition,concentration of graphene,the optimal conditions for the preparation of graphene:determine the electrolyte composition of 0.10 mg mL-1 and concentration of 0.10 mg mL-1 Mg(NO3)2·6H2O solution,the oxidation time is 5 min,the oxidation voltage is 40 V the calcination conditions of 450 ?,2 h.FE-SEM observation showed that the surface of the electrode film is a three-dimensional flower shaped structure,the lower the well-proportioned porous film is a special combination of film structure,and the effects of electrolyte composition,graphene concentration,oxidation voltage and oxidation time on the morphology of the film structure of the electrode surface significantly.The results of XRD show that the oxide film prepared by anodic oxidation is anatase at 450 ? and has good crystallinity.The results of XPS show that the thin film electrode mainly contains four elements:Ti,O,N and C,and the N element is doped into the TiO2 lattice in the form of substitution and gap.UV-vis-NIR tests show that the films have good optical absorption properties from ultraviolet to near infrared(200-2500 nm).The results show that the TiO2 thin film electrode can respond well to the sunlight.Especially in the role of 800 nm has a very strong absorption,calculated by the formula to obtain the lowest band gap can be reduced to 0.52 eV.(2)Photoelectrochemical properties of solar light responsive TiO2 film electrodeThe increase of the thickness,the specific surface area and the porosity of the TiO2 film will increase the photocurrent density.The TiO2 film electrode has higher photocurrent density under UV light,simulated sunlight and solar light were 2.5 mA cm-2,0.35 cm-2and1.1 mA cm-2.Linear-sweep showed that the TiO2 membrane electrode flat band potential is-0.85 V,the carrier can produce more,under the condition of light on light response can quickly generate electron hole pairs,and the light is turned off after the very slow decay shows that the recombination of electron hole slow.It embodies excellent photoelectrochemical properties.(3)Photocatalytic hydrogen production of solar light responsiveTiO2The better hydrogen production by using Pt as anode and NaOH as electrolyte.The hydrogen production rate of TiO2 film electrode under different preparation conditions was studied.Increase the thickness of the TiO2 film,specific surface area,porosity,can better achieve hydrogen production.Different light sources also affect the hydrogen production effect,the TiO2 membrane electrode can be used to simulate the sunlight,as well as the actual concentration of sunlight,the use of solar light.The results show that the TiO2 thin film electrode can respond well to the sunlight.In the accumulation of solar irradiation,hydrogen production rate can achieve 65 ?mol h-1 cm-2,showed that the sun has better hydrogen production activity response type TiO2 membrane electrode,has practical application in the direct conversion of solar energy into hydrogen energy potential.