Synthesis And Photoelectrochemical Performance Of WO₃ Composite Photoanodes

Photoelectrochemical(PEC) water splitting provides the capability of capturing the solar energy and transferring it directly into chemical bonds. As one of the promising ways to solve the global energy crisis, PEC water splitting for hydrogen production has aroused people's attention. Nowdays, extensive attention have been focused on finding appropriate semiconductor materials. Here we innovatively propose a simple synthetic method for preparing highly photoactive WO3 films, which were used to modify the surface of ?-Fe2O3 nanorod arrays to achieve ?-Fe2O3@WO3 composite photoanode. The most important part was that PEC splitting of natural seawater with pristine WO3 and composite ?-Fe2O3@WO3photoanodes were reported firstly in the thesis, respectively.WO3 films were prepared on fluorine-doped tin oxide(FTO) coated glass by a new deposition-annealing(DA) process from WCl6-C2H5 OH precursor, and were used as photoanode for PEC splitting of natural seawater. The PEC performance was optimized simply by varying the concentration of precursor solution and(or) DA cycles. A maximum photocurrent density of 1.9 m A/cm2 was achieved in the sample from 40 m M precursor solution and 25 DA cycles. After 3 h continuous illumination, 90% of the initial photocurrent density still remained, which imply the good photostability for PEC splitting of seawater.Through simple hydrothermal growth and DA process, ?-Fe2O3@WO3 nanorod arrays were grown on the surface of FTO coated glass. We adjusted the mole ratio of W/Fe to optimize the PEC performance by varying DA cycles. The photocurrent density reaches about1 m A/cm2 at 1.23 V vs RHE under the illumination of 100 m W/ cm2(AM 1.5G), which is 50 times as that of the pristine Fe2O3 nanorod arrays under the same conditions. More importantly,when the materials were used as photoanode for PEC splitting of natural seawater, the performance was kept as well. After 5 h continuous illumination, 65% of the initial value of photocurrent density still remained. A possible mechanism for the improved performance of the hybrid photoanode was proposed based on our experimental results.