| Nowadays,the global energy crisis and the increasingly serious environmental problems have prompted people to accelerate the development and utilization of clean and sustainable new energy.Hydrogen energy is considered as the most potential renewable energy in the future because of its high energy density and clean and pollution-free characteristics.The technology of hydrogen production by electrocatalytic water decomposition is considered to be one of the most mature and potential hydrogen production technologies because of its advantages of convenience,high efficiency and no pollution.The electrocatalytic water decomposition consists of two semi reactions,hydrogen evolution reaction(HER)in the cathode and oxygen evolution reaction(OER)at the anode.Oxygen evolution reaction(OER)is considered as the speed determination step of electrocatalysis process.It is a multi-step and four electron process uphill reaction.Its reaction dynamics is poor and the over potential is high,which limits the overall energy conversion efficiency,and greatly hinders the development of hydrogen production by electrolysis water in industry.Therefore,it is necessary to develop the high catalytic performance and high stability catalytic materials needed for the decomposition of electrocatalytic water.Layered double hydroxide(LDH)is commonly known as hydrotalcite,which has the characteristics of chemical composition and corresponding physicochemical properties.The layered nickel iron double hydroxide(NiFe-LDH)has become a hot research hotspot in recent years because of its advantages,such as the adjustable chemical composition,high ionic conductivity and good stability in alkaline environment.Meanwhile,transition metal phosphates(TMP)is considered as good substitutes for noble metal catalysts because of its metal properties,excellent activity,high stability and high conductivity.In this paper,the layered nickel iron double hydroxide(NiFe-LDH)is synthesized by a simple hydrothermal method,and then nickel iron double incomplete phosphide(NiFeP)is prepared by low temperature phosphating.A layered electro catalyst NiFe-LDH is designed and constructed.The electrocatalytic properties of the layered nickel iron double hydroxide(NiFe-LDH)layer are further improved by hydrothermal synthesis on the surface of NiFeP.The preparation method,morphology,element composition and electrocatalytic oxygen evolution performance of the catalysts are further studied.The research content of this paper mainly consists of the following parts:In the first chapter,the layered nickel iron double hydroxide(NiFe-LDH)is synthesized by hydrothermal method at 120℃ for 12 h.Then NiFe P incomplete phosphides are obtained by low temperature phosphating modification of NiFe-LDH precursor at different phosphating temperature and time.After a series of characterization of the obtained NiFe P incomplete phosphide,the NiFeP-350 ℃-3 h incomplete phosphide with the best oxygen evolution performance is obtained.In the second chapter,based on the research of NiFe P incomplete phosphide in the first part,in order to obtain the electrocatalyst with better oxygen evolution performance,firstly,the layered nickel iron double hydroxide(NiFe-LDH)is prepared by hydrothermal method at 120℃for 12 h.Then,NiFeP-400℃-5 h complete phosphide is obtained by phosphating NiFe-LDH precursor at 400℃ for 5 h.Finally,a layer of NiFe-LDH precursor is coated on the surface of NiFe P-400℃-5 h by hydrothermal synthesis.NiFeP-LDH with layered structure is prepared by changing the addition amount of NiFeP-400℃-5 h complete phosphide,hydrothermal reaction time and temperature,and a series of characterization of the prepared catalyst is carried out.Finally,the best OER performance of NiFeP-LDH-0.25 g catalyst is obtained by adding 0.25 g NiFeP complete phosphide. |
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