Construction Of Doped TiO₂ Nanostructures On FTO Substrates And Study Of Their Photoelectrochemical Water Splitting Performance

In the context of energy and environmental issues,it is much promising to produce hydrogen through solar light driven photoelectrochemical?PEC?water splitting by using semiconductor materials as photo-electrodes.Titanium dioxide?TiO₂?is a kind of material that is considered to be very suitable for PEC water splitting because of its advantages of low price,non-toxicity and harmlessness,high chemical stability and strong photo-corrosion resistance.However,due to the disadvantages like weak absorption to visible light and high carrier recombination rate,the application of TiO₂ in PEC water splitting is still limited.To improve its PEC performance,modification toward TiO₂ is usually employed.In this thesis,we prepared TiO₂ doped with several elements,including F,Sn and Ce.The study focuses on the dopants quantity,control of the morphology and the PEC water splitting performance.At the same time,the mechanism of PEC performance improvements caused by element doping as well as the basic theory of charge transfer at the semiconductor/electrolyte interface is systematically investigated.Specifically,it includes the following aspects:?1?F/Sn co-doped TiO₂ nanorod arrays were grown on fluorine-doped tin dioxide?FTO?conductive substrates by hydrothermal synthesis.The morphology and PEC properties of TiO₂nanorods were studied through the doping amount and molar ratio of F and Sn elements.It is found that the F and Sn elements are successfully doped into the lattice of TiO₂ and a large number of Ti³⁺are generated in the TiO₂ matrix due to F^-doping.F/Sn co-doped TiO₂ nanorods have a strong ultraviolet response to light from 295-420 nm,therefore,the PEC water splitting performance of TiO₂ materials have greatly improved.For example,the photocurrent density reaches 0.61 mA/cm²?1.23 V vs.RHE?,which is more than 4 times that of undoped TiO₂photoanode.?2?Ce doped TiO₂ nanorod arrays were grown on FTO conductive substrates by hydrothermal synthesis.The morphology and PEC properties of TiO₂ nanorods were studied through the doping amount of Ce,reaction time,heat treatment temperatures and atmosphere.The PEC performance of TiO₂ nanorods improved effectively due to Ce doping.The photocurrent density of Ce-doped TiO₂ photoanode can reach 0.48 mA/cm²?1.23 V vs.RHE?,which is much higher than that of undoped TiO₂ photoanode.The effects of reaction conditions on the PEC properties of the materials were also explored.It is found that the optimal conditions for synthesis TiO₂ photoanode include:Ce doping quantity of 0.5 atm%,a hydrothermal reaction time of 2 hours and a temperature of 450°C as well as a vacuum atmosphere.