The Construction Of Layered Double Hydroxides-Based Hybrid Materials For Electrochemical Application

Two-dimensional?2D?materials have attracted increasing interest in electrochemical energy storage andconversion.As typical 2D materials,layered double hydroxides?LDHs?display large potential in this areadue to the facile adjustableof their composition,structure and morphology.Various preparationstrategies,including in situ growth,electrodeposition and layer-by-layer?LBL?assembly,have beendeveloped to directly modify electrodes by using LDHs materials.Moreover,several composite materialsbased on LDHs and conductive matrices have also been rationally designed and employed in supercapacitors,batteries and electrocatalysis with largely enhanced performances.This paper focus on the construction of LDHs-based composites and its application in electrocatalytic hydrolysis and electrochemical energy storage carried out in a series of trial and research.The controllable synthesis of LDHs-based composites was realized by the method of multi-step hydrothermal process and liquid phase self-assembly.As a result,the electrochemical performance was enhanced.The main contents of this paper are as following:?1?Study on the construction of NiFe LDH@NiCo₂O₄ compositesHerein,for the first time,we demonstrate NiFe-LDH ultrathin sheets with several atomic layers grown on nickel cobalt oxide?NiCo₂O₄?nanowire arrays as an efficient bifunctionalcatalyst toward both HER and OER reaction.Nickel?Ni?foam was used as the electrode scaffold support because of its earth abundance and porous three-dimensional structure.NiCo₂O₄,a typical OER electrocatalyst with high conductivity,was deposited on the Ni foam in the form of rhombus/hexagonal plates interconnected into perpendicular nanowire array morphology,efficientlyfacilitating electron transfer and electrolyte permeation.The electrical conductivity in NiCo₂O₄ has been believed to originate from the presence of Ni³⁺and the electron transfer between Ni²⁺and Ni³⁺.Importantly,the surface of Ni Co₂O₄ was a Ni-rich layer,which served as the seed for the following hierarchical growth of Ni Fe-LDH,ensuring close contact and strong coupling at the interface.?2?Study on the properties of electrocatalytic water splitting of Ni Fe LDH@NiCo₂O₄compositesHerein,the NiFe-LDH sheets were ultrathin of only several atomic layers,combined with its strong coupling with NiCo₂O₄ and the unique hierarchical structure,enabled the hybrid electrode a remarkable overall water splitting performance of only 1.60 V to achieve 10 m A cm^-2 current in single alkaline KOH eletrolyte.