Electrodeposition Of Photoelectrodes?Cu₂O/CuI?CuO? And Their Photoelectrochemical Performance

With the development of current society,developing clean energy is becoming more and more necessary.The photoelectric effect of semiconductor can effectively transform the inexhaustible solar energy into the energy that people can use.Therefore,the development of photoelectric response materials with high photoelectric conversion efficiency have been widely concerned by researchers.In this thesis,we chose photoelectric materials,such as Cu₂O,CuI and CuO as research objects,focusing on the preparation process of two materials through electrodeposition in solution,the effect of CuI layer on photoelectrochemistry of Cu₂O films and the photoelectrochemistry of electrodeposited CuO electrode.The main contents and results are as follows:In the first part,thin Cul layer has been deposited on the electrodeposited Cu₂O film through adsorption I-in acid solution and its effect on the photoelectrochemical properties of Cu₂O has been studied.Cu₂O film was electrodeposited on ITO substrate by reduction of Cu²⁺ from 0.4M Cu?NO₃?₂ solution.The electrodeposited Cu₂O shows[200]preferential orientation and the thickness of the film is about 1.2 um,on the top of Cu₂O is the[111]oriented CuI layer exposed as triangular faces and the thickness is about 500nm.The photoelectrochemical behaviors of Cu₂O and Cu₂O/CuI electrodes were investigated in 0.1 M Na₂SO₄ solution by LSV under dark and light condition.The photocurrent were-0.16 mA/cm² for Cu₂O and-0.55 mA/cm² for Cu₂O/CuI electrodes at-0.25 V vs.Ag/AgCl under illumination,respectively.In addition,electrodeposited Cu₂O and chemical deposition CuI were both p-type semiconductor.By electrochemical impedance spectroscopy?EIS?test,we studied the hole-electron recombination process at the semiconductor/electrolyte interface.The electron lifetime of Cu₂O and Cu₂O/CuI electrodes are 1.34ms and 2.33 ms,respectively.The CuI layer on Cu₂O improves its photoelectrochemical properties resulting from longer electron lifetime and less electron-hole recombination.In the second part,we developed an electrodeposition process to grow CuO electrode onto ITO in Cu?NO₃?₂ solution containing NH₃ ·H₂Oas complexion agent at room temperature.By CV test of the deposition solution,we found that the[Cu?NH₃?₄]²⁺ plays as a catalyst for oxidation of NH3·H20 or H₂O during the electrodeposition.The possible mechanism was discussed.In addition,the structure and composition of CuO film were characterized by XRD,SEM,EDX and XPS.The electrodeposited CuO can perform good stability in 0.1 M KOH solution by transient photoelectrochemical test.Through M-S plot,the carrier concentration of CuO electrode was obtained.