The Synthesis And Electrocatalytic Water Splitting Performance Of Noble Metal-modified FeNi Metal-Organic Frameworks Derivatives

Under the guidance of the"dual carbon"strategy,energy structure transformation is the only road,so hydrogen energy has ushered in a new development opportunity.Hydrogen production from electrocatalytic water splitting is a promising way,as it’s green,clean,efficient and simple.At present,water splitting still relies on precious-metal based catalyst（Pt,Ru O₂,Ir O₂ and so on）.However,it has not been widely adopted,because of high cost,scarce reserves and low atomic efficiency.In addition,catalysts used in industrial production should achieve high current density in a lower overpotential,with robust catalytic performance and corrosion resistance.Therefore,researchers are committed to developing efficient,robust and inexpensive catalysts to improve the overall efficiency of water electrolysis.To a great extent,the electronic structure of catalyst determines the adsorption/desorption capacity of active intermediates and reaction energy barrier.In this paper,noble metal element was modified in Fe Ni Metal-Organic framework material,which effectively modulates the electronic structure and rationally constructs excellent electrocatalyst.The specific research content is shown as follows:I.We used Fe Ni MOF as precursor due to its abundant metal active centers and regular pore structure.After high-temperature calcination and partial phosphorization treatments,we prepared a hybrid catalyst of Pt doped Fe Ni alloy/Fe Ni phosphide-Pt-Fe Ni@C,P.The introduction of Pt element appropriately regulates the electron properties of Pt-Fe Ni@C,P,which is favorable to enhancing the intrinsic catalytic activity.By virtue of the rough and porous morphology,electrochemically active sites were adequately exposed.Pt-Fe Ni@C,P exhibits the outstanding catalytic activity towards HER in 0.5 M H₂SO₄ and 1 M KOH,which rivals the performance of commercial Pt/C.II.Herein,an innovative Ru-modified Ni Fe metal-organic framework（MOF）nanoflake array on Ni foam（Ru-Ni Fe-x/NF）was elaborately designed via spontaneous galvanic replacement reaction（GRR）.To effectively adjust Ru content and optimize catalytic performance,the Ni Fe MOF/NF precursor was soaked in a set of Ru Cl₃ solution at different concentrations.Specifically,these interconnected hierarchical nanoflake array vastly enlarge the contact area of electrocatalyst with electrolytes,and expose more catalytically active sites towards HER.Significantly,the strong electronic interaction between Ru and Ni element can effectively modulate the electronic structure of the material and promote the catalytic activity,as the GRR proceeds.Ru-Ni Fe-（3）/NF only requires the ultralow overpotential of 90 m V and 150m V to reach 100 and 200 m A cm^-2,respectively,with great durability in 1 M KOH solution.III.On this basis,we further explored Ru-Ni Fe-（3）/NF as superior multifunctional electrocatalyst towards OER and UOR.Therefore,Ru-Ni Fe-（3）/NF was functioned as both cathode and anode catalyst for overall water splitting and urea-assisted water splitting,respectively.Ru-Ni Fe-（3）/NF||Ru-Ni Fe-（3）/NF electrode only requires 1.63 V and 1.47 V to attain the current density of 100 m A·cm^-2,preceding Pt/C-NF||Ru O₂/NF.Thanks to the spontaneous GRR,more abundant high-valence Ni species are beneficial to OER and UOR electro-catalysis.Three-dimensional Ni foam（NF）was chosen as the self-supporting substrate,for its multi-channel network structure and great electrical conductivity,then ensuring the rapid liberation of a great deal of gases and long-term operation of electrode material.