Construction,Characterization And Photoelectrochemical Water Splitting Performance Of Hematite Heterojunction Photoanode

Photoelectrochemical water splitting,which converts solar energy into hydrogen,is considered to be one of the best ways to solve the current energy shortage and environmental pollution because of its environment-friendless,non-pollution,high-quality products,the scale of controllable and mild reaction conditions,etc.Among many photoelectrode materials,it makes Hematite??-Fe₂O₃?received widespread attention that hematite??-Fe₂O₃?possesses many advantages,such as suitable band structure,low cost,environmental non-toxic,good stability,high theoretical photoelectric conversion efficiency?15.6%?and photocurrent density(12.6 mA cm^-2).However,the incident photon-to-current efficiency of Hematite is still low due to the inherent defects,such as low separation efficiency of photogenerated carriers and sluggish kinetics of oxygen evolution.In this paper,the hematite heterojunction photoanodes were used to enhance the photo-induced charge separation,transfer efficiency and the kinetics of oxygen evolution,aiming to enhance the incident photon-to-current efficiency of?-Fe₂O₃.The main contents of this paper are as follows:?1?Preparation and study of Au-Pt core-shell nanoparticles/?-Fe₂O₃ composite photoanodes for photoelectrochemical water splittingThe core-shell nanoparticles containing Au-Pt were prepared by successive reduction method.Then the Au-Pt core-shell nanoparticles were grafted onto the?-Fe₂O₃ surface by spin coating following calcination.Electrochemical tests showed that the Schottky barrier was formed between the Au-Pt core-shell nanoparticles and?-Fe₂O₃,which promotes the separation and transmission of the interface charge.In addition,the Photoelectrochemical Performance of the composite photoelectrode is greatly influenced by the the content of platinum.The photoelectric conversion efficiency of?-Fe₂O₃ modified the AuPt_0.2.2 nanoparticles was increased from 5%to 58%.?2?Study on in-situ synthesis and performance of Zn Fe₂O₄/?-Fe₂O₃ heterojunction composite photoanodes for photoelectrochemical water splittingThe Zn Fe₂O₄/?-Fe₂O₃ heterojunction photoanodes were synthesized by in situ high-temperature solid-state reactions,and the charge separation efficiency of the?-Fe₂O₃ was enhanced by the in-built electric field in the heterojunction interface.The crystal structure,morphology and optical absorption of ZnFe₂O₄/?-Fe₂O₃ composite photoelectrodes were characterized by XRD,UV-vis DRS,FESEM,and HRTEM.The photoelectrochemical performance test showed that the introduction of ZnFe₂O₄ improved the photocurrent density and the incident photon-to-current efficiency of the?-Fe₂O₃.The incident photon-to-current efficiency was raised from 5%to 65%.A possible charge transfer mechanism was proposed based the electrochemical test.?3?Preparation and study on Co₃O₄/?-Fe₂O₃ composite photoanodes for the photoelectrochemical water oxidationIn this chapter,the Co₃O₄ nanorods were used to modify?-Fe₂O₃ by facile in-situ synthesis method.The composite photoelectrodes with different content of Co₃O₄ nanorods were prepared by changing the soaking time of?-Fe₂O₃ in the precursor containing cobalt ions.Compared with the original Fe₂O₃,the incident photon-to-current efficiency of optimal 45 Co₃O₄/?-Fe₂O₃photoanodes was raised from 6.5%to 21%.Enhanced photoelectrochemical performance could be attributable to that Co₃O₄ promoted the kinetic process of water oxidation.