Study On Synthesis Of Manganese Based Catalyst And Hydrogen Production Of Electroiysis Water

Increased concern over environmental pollution has triggered an urgent need for finding clean and sustainable energy carrier alternatives to fossil fuels.Solar energy,wind energy,geothermal energy and so on for power generation has become a hot research direction,but energy storage has also become particularly important.As an energy carrier,hydrogen is considered to be the most promising clean energy to replace fossil fuels because of its wide distribution,high combustion efficiency and clean combustion products.The conversion of electric energy to hydrogen energy can not only store energy well,but also use pollution-free energy.Electrocatalytic water splitting is a very promising candidate for large-scale sustainable hydrogen production due to its high purity,environmental friendliness and zero carbon emission.Nevertheless,because of its slow kinetic process,it is often necessary to consume great electricity during the preparation process.Currently,various noble metal-based materials have been used as electrocatalysts for HER（e.g.Pt）and OER（e.g.Ru）to reduce overpotential in order to achieve considerable energy conversion efficiency.unfortunately,the high cost and scarcity greatly limit their wide application in commercial water electrolyzers.In order to solve such problems,reduce the cost of catalysts,and realize the large-scale industrialization of catalysts,this paper studies the cheap transition metal Mn,through the transformation of its structure,morphology and electronic structure,to develop a series of cheap and efficient electrolytic water catalysts.（1）We have prepared novel Mn₂P-Mn₂O₃ heterogeneous nanoparticles hosted in a P,N-doped three-dimensional porous carbon framework.Of these,Mn₂P-Mn₂O₃/PNCF displayed ultrahigh stability as a bifunctional electrocatalyst for efficient hydrogen evolution reactions（HERs）and oxygen evolution reactions（OERs）in alkaline electrolytes.These properties are a result of the abundant heterogeneous interfaces,optimized electronic configurations and hierarchical pore structure of the Mn₂P-Mn₂O₃/PNCF catalyst.This material has a closed zero calculated Gibbs free energy for adsorbed H of-0.013 e V,and can achieve current densities of 10 m A cm^-2 and 100 m A cm^-2for HER and OER,respectively,whilst requiring only low overpotentials of 98 m V and 330 m V,respectively.In addition,an alkaline electrolyzer with Mn₂P-Mn₂O₃/PNCF as both the anode and cathode demonstrates a nearly comparable activity and higher stability than the present state‐of‐the‐art,Pt/C||Ru O₂/C,for full water splitting.Mn₂P-Mn₂O₃/PNCF shows great potential for the economical,large-scale production of H₂.（2）We synthesized a nanocuboidal MnCO₃ precursor using microemulsion precipitation and coated in situ with dopamine;thereafter,we processed it using simultaneous carbonization,sulfization.Accordingly,we obtained Mn–MnO@NSC,avoiding the traditional multi-step synthesis process of sulfization and subsequent carbonization.In contrast to the structure of bulk materials,that of the MnS–MnO nanocube,owing its large specific surface area,enhances the catalytic efficiency by fully exposing the catalytic active sites.MnS–MnO@NSC has rich heterogeneous interfaces and an optimized electronic structure,which greatly promotes electrochemical reactions.The encapsulation of MnS–MnO nanocubes in a N,S-co-doped carbon shell significantly improved the durability and catalytic activity.MnS–MnO@NSC exhibited excellent stability as an efficient bifunctional electrocatalyst for the hydrogen evolution reaction（HER）and the oxygen evolution reaction（OER）in KOH solution.In the HER,the overpotential was as low as 124 m V at a current density of 10 m A cm^-2,while in the OER,it was only 340 m V at 100 m A cm^-2 under the same conditions.Moreover,a MnS–MnO@NSC||MnS–MnO@NSC electrolyzer exhibited almost comparable activity and higher stability compared to those exhibited by the state-of-the-art Pt/C||Ru O₂/C system for full water splitting in KOH solution.