| Photoelectrochemical(PEC)water decomposition system can convert solar energy into clean hydrogen energy,which is one of the ideal ways to solve the current energy and environmental crisis.As one of the important components of PEC water decomposition cell,the photoelectrode has excellent properties which can effectively improve the conversion efficiency of the cell to light.Therefore,in order to improve the water decomposition efficiency of PEC,looking for semiconductor materials with application potential and the design and construction of semiconductor photoanode are the core issues of current research in this field.Tungsten trioxide(WO3)has been widely used as a photoanode because of its strong electron transport capacity,moderate carrier diffusion distance(～150 nm)and good stability.However,the gap width of WO3 is relatively large,and the utilization efficiency of sunlight is low.On the other hand,the high recombination rate of photogenerated carrier of WO3 leads to the low water decomposition efficiency of PEC in photoanode.To solve the above problems of WO3,WO3 photoanode was improved and optimized by constructing heterostructures in this paper.WO3 nanoarray was modified with Prussian blue(PB)to obtain WO3@PB composite photoanode.After heat treatment,Fe2O3 nanoparticles were synthesized in situ on the WO3 surface to form WO3@Fe2O3 core-shell heterostructures with WO3 nanorods as the center,and used as the photoanode to study the photochemical properties.Specific research contents are as following:(1)Design and preparation of WO3@PB core-shell nanostructures.WO3 nanorods were grown on FTO substrates by hydrothermal method.The WO3 nanorods with the best photoelectric properties were obtained by adjusting the content of acetonitrile and the deposition time.The WO3@PB core-shell composite was prepared by electrochemical deposition of PB.The phase and morphology of the prepared samples were characterized by SEM,XRD,XPS and TEM.The photoelectric chemical properties of the prepared samples were tested by LSV,i-t,EIS and IPCE.The results show that the size of WO3 nanorods is 50-150 nm,and PB grows on the surface of WO3 nanorods,forming WO3@PB cored-shell nanorods array.Compared with pure WO3,WO3@PB composite showed better photocatalytic performance.The photocurrent density of WO3@PB-100 photoanode at 1.23 V vs.RHE is 0.49 mA/cm2,which is 2 and 40 times that of pure WO3 and PB,respectively.This is because while the existence of PB improves the light absorption efficiency,WO3 and PB form heterojunction,which promotes the separation and transfer of charge carriers and improves the life of photoelectric carriers,thus significantly improving the photoelectric performance.(2)WO3@Fe2O3 core-shell nanostructure was designed and fabricated.Using WO3@PB prepared in the previous chapter as the precursor material,Fe2O3 particles with high surface binding force were synthesized in situ on the surface of WO3 nanorods by heat treatment method.Due to the better light absorption capacity and effective electron transfer of Fe2O3,the photocatalytic performance of WO3 matrix was improved.In the UV-Vis figure,the absorption efficiency of the WO3@Fe2O3 composite anode to sunlight increased,and the separation efficiency and migration rate of the photogenerated electrons and holes improved the photocatalytic performance of the composite significantly.The initial potential of WO3@Fe2O3 photoanode prepared at 400℃ is 0.6 V at 1.23 V vs.RHE,which is significantly lower than that of WO3 and Fe2O3 electrode.The photocurrent density is 1.22 mA/cm2,which is 5 times higher than that of pure WO3. |
