| Spin and charge properties are the inherent properties of electrons.In the past,people paid more attention on traditional microelectronics that uses electric charge as information storage and transmission medium.However,with the advancement of society and the development of science and technology,tranditional electronic devices can not meet the demands of emerging fields.Therefore,in order to prepare nanosized electronic devices,people began to reconsider and study the spin properties of electrons.The introduction of intrinsic spins and magnetism in nano-sized materials will be an important step in the future development of spin devices.Therefore,the rational development and utilization of electron spin not only has a profound influence on the information industry,but also has important research significance on the regulation of the physical and chemical properties of the materials.In this dissertation,inorganic solid materials are selected as the research object,and the spin-related properties in the materials are regulated to optimize physical and chemical properties.In this paper,we focus on exploring the correlation between spin properties and magnetoelectric transport properties as well as electrocatalytic reaction performance.Through the introduction of dual defects,coordinated regulation of oxygen vacancies and doping,stress engineering,and the formation of strong coupling bonds between the sample and the substrate,the magnetoelectric transport properties performance and electrocatalytic activity can be enhanced.The specific content of this paper includes the following points:1.Due to the advantage that the transition-metal-dichalcogenide can be exfoliated into ultrathin nanosheet,it is considered as a promising material to prepare a nano-sized spin device.However,due to its lack of intrinsic magnetism and spin,the two-dimensional transition metal chalcogenide cannot be used to prepare spin devices.In this paper,a dual-defect method of introducing a single Se anion defect and a Ti atom intercalation into TiSe2 material is proposed to successfully introduce high spin polarization and local magnetic moment into the framwork,realizing 2D half-metalic properties in TiSe2 nanosheets with high spin polarizability and intrinsic ferromagnetism.The formation of Se defects and self-doping of Ti atoms introduce unpaired 3d1 electron into the Ti-based framework,achieving a transition from Ti4+ to Ti3+,and thus forming a local magnetic moment that benefits from external field adjustment.Through magnetic transport properties,dual-defects T-TiSe1.8 nanosheets achieve large negative magnetoresistance effect of-40%was obtained at a temperature of 10 K and a magnetic field of 5 T,which is expected to be applied in spintronic field.2.By hydrogen treatment method to produce oxygen defects in the Yb-doped perovskite Ca0.9Yb0.1MnO3 to regulate the Mn spin states,synergistically optimizing high conductivity and a 0.81 eg electron-filled degree.The process of forming oxygen defects can adjust the valence of Mn in B site,gradually transform Mn4+ into Mn3+,and achieve synergistic optimization of the eg filling-level of the electron and the conductivity of the material.Compared to the original sample,Ca0.9Yb0.1MnO3-?hydrogen treatement under the temperature of 350? showed a lower overpotential and high current density.The Ca0.9Yb0.1MnO3-? sample had a 100 fold higher OER activity than the untreated bulk material.3.By strain engineering,LaCoO3(100)with a stable intermediate spin state was prepared and demonstrated pure spin state modulation.First,magnetic properties and corresponding XANES spectral results confirmed that LaCoO3 epitaxial films with different lattice orientations(recorded as LaCoO3(100),LaCoO3(110),and LaCoO3(111)films)can bring CoO6 octahedra distortion with different degrees,which induces the transition of the spin configuration from a low spin state(LS t2g6eg0)to an intermediate spin state(IS t2g5eg1),further optimizes the electrical conductivity,eg electron filling-state and adsorption free energy.Thanks to the synergistic optimization of these three factors,the prepared LaCoO3(100)film exhibits better OER catalytic activity than the other two oriented films..4.Aiming to solve the problem that there are no strong coupling bonds as fast electron transport channels between the substrate and the catalyst,we developed a strongly-coupled catalysts:oxygen-vacancies-rich CoO nanoparticles grown on boron and nitrogen co-doped graphene substrates with strong coupling Co-N-C bonds(named CoOx NPs/BNG).Due to the strong coupling Co-N-C bonds between the carbon atoms in the graphene and the Co atom in CoOx nanoparticles,the CoOx NPs/BNG composites have excellent electron transfer ability.Moreover,strong coupling Co-N-C bonds can protect the CoOx nanoparticles from agglomerating together and easily expose more active sites,and further promoting bifunctional electrocatalytic activity.This material exhibits excellent OER catalytic activity and high ORR performance comparable to commercial Pt/C. |
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