Surface/Interface Structural Regulation Of NiFe-LDH And Corresponding Electrocatalytic Water Splitting

Fossil energy can cause a lot of carbon dioxide and greenhouse gas.Electrolysis of water to produce hydrogen is a simple,low-cost and environmentally friendly method.Electrolysis of water involves two half-reactions:hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).OER is the bottleneck of water electrolysis because of slow kinetics of the OER reaction and the four-electron process involing H-O bond breaking and O-O bond recombination.Development of efficient and stable OER catalysts is a hot issue.In the past,traditional industrial OER catalysts were mostly noble metal catalysts(Pt,Ir,Ru,etc.),and their catalytic activity and stability were difficult to meet practical applications.Therefore,transition metal-based materials with outstanding OER properties under alkaline conditions have received extensive attention,among which Nickel-iron double layer hydroxide(NiFe-LDH)has the best OER property.However,there are some problems restricting its OER activity,such as the small specific surface area,poor electrical conductivity,and poor stability of the stack-structure.In this paper,NiFe-LDH is taken as the research object.After exfoliation,doping elements adjust the surface structure and hetero-interface recombination to improve its charge transfer rate and further enhance the OER activity.The characterization and electrochemical properties were explored to explain the reaction mechanism of NiFe-LDH’s surface-interface structure regulation to enhance its OER properties.1.Spin-state Inversion in Non-precious Na Single Atoms Decorated NiFe-LDH Monolayer for Efficient Electrocatalytic Water OxidationPreparing highly efficient electrocatalysts via structural or electronic manipulation always holds great interest in water electrolyzers.Here,we introduce the non-precious Na atoms to NiFe-LDH and investigate the effect of electronic configuration changes on electrocatalytic water oxidation.The electrochemical tests reveal that the NiFe-LDH monolayer decorated with Na atoms(Na/NiFe-LDH)possesses superior oxygen evolution reaction(OER)performance,achieving an overpotential of 279 mV at the current density of 100 mA cm-2 with a loading amount of 1 mg cm-2.The experimental characterizations and theoretical calculations highlight the effect of the Na-O3 motif on improving the intrinsic OER activity and facilitating surface charge transfer kinetics.Particularly,the formation of the Na-O3 motif reduces the strength of the Fe-O bond in the NiFe-LDH skeleton,and the increased local charge around the adjacent Fe atom induces the spin-state inversion for Fe 3d orbitals,which accounts for the enhanced OER performance.This work demonstrates an effective method to enhance the OER activity of NiFe-LDH through spin-state regulation.2.Pt Nanoparticle-Decorated NiFe-LDH Monolayer nanosheet toward overall water splittingDesigning effective bifunctional catalysts for water electrolysis becomes a key research issue.Through different electrodeposition times,Pt atoms were modified onto NiFe-LDH monolayer nanosheets to obtain bifunctional water electrolysis catalyst Pt/NiFe-LDH.Due to the surface synergy,the presence of Pt atoms enhanced the conductivity and HER Catalytic activity.Through electrochemical tests,it can be seen that Pt/NiFe-LDH exhibits excellent properties of total water splitting.Compared with traditional commercial IrO2-Pt/C electrodes,the Pt/NiFe-LDH electrocatalyst has excellent properties and has broad application prospects.