Research On The Fabrication Of Fe₂O₃ And Cu₂O Oxide Semiconductor Nano-materials For Photoelectrochemical Water Splitting

One of the efficient approaches to resolve the energy crisis and environmental pollution is developing clean and sustainable energy.Among the clean energy,solar energy and hydrogen energy are the cleanest energy.How to make use of the solar energy and convert it to the hydrogen energy is crucial.Inspired by the photosynthesis,the photoelectrochemical（PEC）water splitting was exploited to convert solar energy to hydrogen energy.It is the most promising energy conversion technology due to the low cost and environmentally friendly.In this Master thesis,we focused on the synthesis of hematite（Fe₂O₃）and cuprous oxide（Cu₂O）nanomaterials,which serve as the photoanode and photocathode respectively.In addition,we deeply explored the PEC water splitting performance of the as prepared photoelectrode.The main work and findings of the thesis are listed as follows:1.Ti-Fe₂O₃-FeOOH photoanode was prepared successfully.The Ti dopant and FeOOH surface modification could improve the PEC performance of the Fe₂O₃ indubitably.The photocurrent density of the Ti-Fe₂O₃-FeOOH(2.31 mA cm^-2 at 1.23 V_RHE)shows a 4.6-fold increase compared with that of pure Fe₂O₃ photoanode(0.50 mA cm^-2 at 1.23 V_RHE)under AM1.5 G solar illumination.The as prepared photoanode presents a synergistic effect between Ti dopant and FeOOH surface modification;the Ti dopant could improve the electron-hole separation efficiency of the Fe₂O₃ efficiently.With Ti doping,the separation efficiency of Ti-Fe₂O₃ and pure Fe₂O₃ photoanode is 31.2%and 21.3%respectively,in addition,the separation efficiency of Ti-Fe₂O₃-FeOOH and Fe₂O₃-FeOOH photoanode is 35.9%and 17.5%respectively.After modifying with FeOOH,the transfer efficiency of Fe₂O₃-FeOOH and pure Fe₂O₃ photoanode is 66.8%and 31.5%respectively,in addition,the transfer efficiency of Ti-Fe₂O₃-FeOOH and Ti-Fe₂O₃ photoanode is 81.9%and 70.6%respectively.Moreover,the improvement of electron-hole separation efficiency and transfer efficiency result in the increase of the PEC performance.2.Cu₂O photocathode was prepared successfully.The PEC performance of the Cu₂O improved significant after atomic layer deposition（ALD）of TiO₂.The photocurrent density of the as prepared photocathode(-0.43 mA cm^-2 at 0 V_RHE)shows a 4.3-fold increase compared with that of pure Cu₂O photocathode(-0.10 mA cm^-2 at 0 V_RHE)under AM 1.5 G solar illumination.However,the PEC performance of the as prepared photocathode decayed sharply due to the instability.The protection of TiO₂ alone is limited due to the non-uniformity and pinholes of the TiO₂ layer.The Cu₂O will be reduced during the PEC measurement.