【作者】 李娜；

【导师】 胡适；

【作者基本信息】 天津大学 ， 化学， 2020， 硕士

【摘要】 电解水制氢是缓解能源短缺与环境问题的有效方法之一。析氧反应（OER）因其缓慢的动力学和较大的过电位阻碍了电解水的发展。因此,设计具有高催化活性和稳定性的催化剂去实现电解水的进一步应用势在必行。RuO₂和IrO₂被认为是OER的理想催化剂,但高成本和稀缺性阻碍了它们在商用电解水中的大规模应用。基于以上讨论,本论文就低成本的二维水合锰酸钠(Na_0.55Mn₂O₄·1.5H₂O)进行实验,通过调控与活性材料的复合、不同层间离子,实现了催化剂反应活性的提高。具体内容如下:1.采用简单的两步合成步骤合成了双金属层状氢氧化物（LDHs）和Na_0.55Mn₂O₄·1.5H₂O（NaMnO）复合的电催化剂。该复合物在电化学测试中表现出良好的OER活性。具体地讲,NiFe LDHs/NaMnO的过电势为260 m V,塔菲尔斜率为21 m V dec^-1,都优于单纯的NiFe LDHs(330 m V,53 m V dec^-1)和NaMnO(490 m V,74 m V dec^-1),同时也优于商业RuO₂(330 m V,52 m V dec^-1)。催化性能的提高在于两个带相反电荷的NiFe LDHs和2D NaMnO纳米片结合。两者直接界面接触缩短了电子转移距离,加快了电子转移速率。同时,有效地阻止了自身的团聚,暴露更多的NiFe LDHs活性位点。2.以2D NaMnO纳米片为基底,利用[M（N₂H₄）_y（H₂O）_z]^x+(M=Co²⁺,Ni²⁺,Fe³⁺)配合物有效地将Co²⁺,Ni²⁺,Fe³⁺输送到含Na⁺的2D Na_0.55Mn₂O₄·1.5H₂O纳米片的层间区域。通过X射线衍射（XRD）和X射线光电子能谱（XPS）证明阳离子成功地插入了2D Na_0.55Mn₂O₄·1.5H₂O纳米片。插层Co,Ni,Fe的NaMnO其OER活性显著提高,过电势分别为400 m V、420 m V、320 m V,其中插层Fe的NaMnO所需过电势远低于原始的NaMnO（450 m V）。OER活性的提高归因于层间间距变小,很好地加快了层间电子转移的速率。更多还原

【Abstract】 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.更多还原