Preparation And Modification Of 2D Nanomaterials Based On Hydrated Layered Sodium Manganite And Electrocatalytic Performance For Oxygen Evolution Reaction

Electrolysis of water to produce hydrogen is one of the effective methods to alleviate energy shortages and environmental problems.Oxygen evolution reaction（OER）hindered the development of electeolysis water due to its sluggish kinetics and high overpotential.Therefore,it is imperative to design catalysts with high catalytic activity and stability to realize the further application of electrolytic water splitting.RuO₂ and IrO₂ are considered ideal catalysts for OER,but their high cost and scarcity prevent large-scale application in commercial electrolytic water.Based on the above discussion,our research mainly based on low-cost two-dimensional hydrated sodium manganate(Na_0.55Mn₂O₄·1.5H₂O).The catalytic activity was improved by controlling the nanocomposite of the material and the ions between layers.The specific contents are as follows:1.Using simple two-step synthethic method to fabricate layered double metal layered hydroxide（LDHs）and Na_0.55Mn₂O₄·1.5 H₂O（NaMnO）nanocomposite.The compounds showed good OER activity in electrochemical tests.To be specific,the overpotential of NiFe LDHs/NaMnO is 260 m V,Tafel slope is 21 m V dec^-1,which is superior to the pure NiFe LDHs(330 m V,53 m V dec^-1)and NaMnO(490 m V,74 m V dec^-1),and the commercial RuO₂(330 m V,52 m V dec^-1).The catalytic performance was improved by the direct interface contact between the NiFe LDHs and 2D NaMnO nanosheets with opposite charge,which shorten the electron transfer distance and accelerate the electron transfer rate.Meanwhile,the direct interface contact by electrostatic attraction,which effectively prevents its agglomeration and exposes more active sites of NiFe LDHs.2.The Co²⁺,Ni²⁺,Fe³⁺were effectively transported to the interlamellar region of2D Na_0.55Mn₂O₄·1.5H₂O nanosheets containing Na⁺by[M（N₂H₄）_y（H₂O）_z]^x+(M=Co²⁺,Ni²⁺,Fe³⁺)complexes.The cations were confirmed to insert into the 2D Na_0.55Mn₂O₄·1.5H₂O nanosheets successfully by X-ray diffraction（XRD）and X-ray photoelectron spectroscopy（XPS）.The OER performance of Co,Niand Fe confined in the layer region of NaMnO is significantly improved,and the overpotential is 400m V,420 m V and 320 m V respectively,among which the overpotential required by Fe confined in the layer region of NaMnO is much lower than the original NaMnO（450m V）.OER performance improved due to the reduced interlayer spacing,accelerated the rate of interlayer electronic transfer.