Preparation And Study On The Properties Of Photocathode For Metal Oxidation/Sulfur Compounds

The excessive use of fossil fuels leads to the depletion of non-renewable resources and brings some severe pollution.So it's necessary to find a new clean energy to meet the demands of human's development and protect global environment.Hydrogen with merits of high burning value,no carbon footprint and no burning product,is considered as a new kind of clean energy.With the development of hydrogen technology,photochemical decomposition water become the most promising way to prepare hydrogen.Recently,the research of photoelectric anode material become more and more popular.But the research on photocathode materials is relatively less,which hinders the rapid development of photochemical decomposition water.As a result,designing a efficient and stable photocathode for hydrogen production is significant in the area of water splitting.In my work,according to the principle of energy level matching,the sulfur compounds were applied to build a new type of photocathode,and the photoelectric chemical properties were studied.The following is the main research content of this paper:1.Preparation and properties of MoO₃/CdSe photocathodeMolybdenum oxide was n-type in nature,and its apparent hole-selectivity was due to the formation of a highly p-type doped interface with conjugated polymers having ionization energies?IE?lower than the oxide work function?WF?.Its large band gap?3.0 eV?and high transmittance enabled illumination through the hole-selective layer.Recently,amorphous molybdenum oxide had emerged as a promising hole-selective for high-efficiency OPVs.FTO/MoO₃/CdSe photocathode was prepared by using CdSe instead of organic dye as absorbent material.The composite films were characterized by SEM,UV-Vis and chronoamperometry.Results showed that the electrode hasd a good optical absorption capacity and perfect photoelectric conversion.Moreover,the electrode performed high stability for 10000 s.2.Preparation and properties of Co₃O₄/CdSe/MoS₂ photocathodeCobaltosic oxide?Co₃O₄?was a typical and environmentally friendly p-type metal oxide,with the excellent physical-chemical properties,which had been widely used in lithium batteries,super capacitors catalysts and photoelectrochemical devices.At present,the Co₃O₄with p-type behavior had been mostly served as catalyst and co-catalyst in the oxygen evolution reaction,but the researches on cobaltosic oxide for photoelectrochemical hydrogen evolution reaction was few.In this work,cobalt oxide?Co₃O₄?nanowires were used as the hole-selective layer mater.The FTO/Co₃O₄/CdSe electrode was prepared by using inorganic semiconductor nanomaterial,CdSe as the absorbent material and Co₃O₄ as the hole conduction layer material.Then,MoS₂ was deposited on the face of FTO/Co₃O₄/CdSe electrode.As a result,FTO/Co₃O₄/CdSe/MoS₂ electrode exhibited higher catalytic activity than FTO/Co₃O₄/CdSe electrode.Fuethermore,the FTO/Co₃O₄/CdSe/MoS₂ electrode showed photocurrent of-70?A·cm^-2 and operational activity of several hours.3.Preparation and properties of ITO/PbS photocathodeTin-doped indium oxide?ITO?was a n-semiconductor with a band gap about 3.7-3.8 eV.Planar ITO thin film had been widely used as the transparent conductive substrate in organic photovoltaic devices and organic light-emitting diodes.Recently,Tin-doped indium oxide had emerged as a promising hole-selective layer for high-efficiency OPVs.In this photocathode,holes were injected into the conduction band?CB?of ITO,instead of the valence band?VB?of the traditional p-type semiconductor.In this work,we reported a novel photocathode employing PbS as photoactive material and tin-doped indium oxide?ITO?as hole selective layer.FTO/PbS electrode showed photocurrent of-75?A·cm^-2 and operational activity of 9hours.The key factors for hole transfer were investigated.These results showed that ITO was a promising holes transfer material for photoelectrochemical photocathode.