Preparation Of ?-Fe 2 O 3 /rGO Composite And Study Of Its Photoelectrocatalytic Properties

With the development of the economy,energy shortage and environmental pollution is more and more severe.The increasing demand for sustainable green energy directly promotes the development of solar energy conversion and storage technology.Hydrogen is a highly efficient and environmentally friendly energy.Photoelectrochemical is a promising method to get oxygen and hydrogen from water,which use solar energy as the driving force and semiconductor oxide served as the medium.The fabrication and design of semiconductor oxide electrodes has become a hot spot.?s a new material,graphene has been widely used in the field of energy.In this thesis,we focus on the preparation of graphene and one-dimensional ?-Fe₂O₃ arrays.Moreover modified one-dimensional ?-Fe₂O₃ arrays with ultra-thin reduced graphene oxide.In this paper,graphene oxide was prepared by the improved Hummers method,and graphene was prepared by thermal reduction method.Graphite was used as raw material,concentrated sulfuric acid was used as intercalation and KMnO4 was used as oxidant.By controlling the reaction time,the effect of time on the oxidation degree of oxidation products was studied.?fter the reaction of 4 h,the content of oxidation group did not increase with the increase of reaction time.The effects of substrate difference,ultrasonic time,sample preparation methods and fragmentation on the morphology of graphene oxide were investigated by atomic force microscopy??FM?.The reduction of graphene oxide was studied by thermal reduction method.The effect of reduction time and temperature on the recovery of sp2 in graphite was investigated.The conductivity of graphene reached 10000 S/m at 400?? and 30 min.One-dimensional ?-Fe₂O₃ nanorod arrays were prepared through two steps procedure?hydrothermal-annealing?on FTO substrate.The influence of hydrothermal temperature on the morphology of nanorod arrays has been explored,it shows that samples which grows at 80-90?? have the best morphology.The paper choose 90?? as hydrothermal temperature.The ?-Fe₂O₃/rGO composite was prepared by the spin coating-reduction two steps method.The effects of spinning velocity and the size of graphene oxide on the morphology of the composite were studied.The effects of the amount of graphene on the optical and photocatalytic properties of ?-Fe₂O₃/rGO were investigated by using different spinning times.?fter three times of spin coating,the optical absorption performance reached the maximum.?t-0.17 V the photocurrent density of ?-Fe₂O₃ was about 0.015 m?/cm2,and the photocurrent density of ?-Fe₂O₃/3rGO was 0.095 m?/cm2.In the meantime the conversion efficiency was increased by a factor of 7.4.The J-t curves under intermittent illumination show that the instantaneous photocurrent density of ?-Fe₂O₃ is 0.018 m?/cm2,and the photocurrent density of ?-Fe₂O₃/3rGO is 0.052 m?/cm2 when the external bias voltage is 0 V.?-Fe₂O₃ has a series of advantages as a kind of anode material,its disadvantages restrict its application.In this paper,?-Fe₂O₃ modified by graphene.Graphene,firstly,served as a fast channel of photogenerated electrons in ?-Fe₂O₃/rGO composites to suppress the recombination of photogenerated electrons and holes.Secondly,as the surface passivation film,which results in the increase in the kinetics of oxygen evolution and reduction in the initial bias voltage.Meanwhile,the introdaction of graphene narrowed the band gap of ?-Fe₂O₃ and improved the absorption performance.