Preparation And Photoelectrochemical Performance Investigation Of Semiconductor Photoanode For Water Splitting

In order to prevent the further deterioration of the energy crisis,people began to excavate and study the new energy.Compared to wind energy,water energy,tidal energy and other renewable energy,solar energy is the most popular energy.Currently,the research mainly focus on the photochemical reaction method,which uses solar energy to split the water and generate hydrogen and oxygen to achieve the conversion of solar energy into hydrogen energy.TiO2 is widely used as a photo anode semiconductor material because of its good stability,safety and non-toxic.But the band gap of TiO2 is relatively wide(about 3.2 eV).this property makes it can only use 5%less than UV in sunlight.In addition,the recombination of photo generated electrons and holes,therefore,carries on the modification to improve its response to visible light to enhance the photocatalytic activity can become the main work at now.This paper focuses on the TiO2 semiconductor material,the modification of TiO2 to enhance the light response and enhance the photocatalytic performance become a popular research field.In this paper,our work was centered on optimized modification of the TiO2 semiconductor material in two parts.The one is surface modification quantum dot sensitized TiO2 nanotube arrays by atomic layer deposition coating passivation layer and study the photoelectrochemical properties;the second is to synthesize MoSe2/TiO2 composite materials and study the photocatalytic properties.In the first experiment,titanium dioxide nanotube arrays(TNTAs)were prepared by anodic oxidation,and TNTAs/QDs was prepared by successive ionic layer adsorption and reaction.Finally,atomic layer deposition(ALD)technology was used to deposit different oxide covering layers of the same thickness(1.5nm)on TNTAs/QDs,and the photoelectrochemical properties of each sample were compared.Under 100 mW/cm2 simulated solar light,the photocurrent of the Al2O3 layer electrode shows the highest photocurrent density of 5.6 mA/cm2,the photocurrent density of the ZnO layer electrode is 5 mA/cm2,and the photocurrent density of the TiO2 layer is 4.3 mA/cm2.Three kinds of oxide passivation layers enhance the photoelectrochemical performance of TNTAs/QDs system,aslo the potential mechanism was studied by electrochemical impedance spectroscopy(EIS)and Mott Schottky(Mott-Schotty)test.The second experiments is using sodium molydate,selenium powder as raw material and sodium borohydride as to synthesize flower like MoSe2 by hydrothermal method.The samples were characterized by SEM,TEM and Raman.Synthesize MoSe2/TiO2 composites by hydrothermal method by using the prepared samples and tetrabutyl titanate.The composites were further characterized by UV-vis,XRD and PL spectroscopy,and the photocatalytic mechanism were also analyzed.