Study On Hydrogen Evolution Reaction Efficiency Of Flexible Single Crystal Manganese Oxide Film

Perovskite-type oxides have the advantages of cheap price,abundant reserves,good conductivity,stable state,etc.,and become the most valuable candidate materials in the field of electrocatalysis.In the transition metal oxides,due to the strong correlation,the electron-electron and electron-lattice interactions are strong and cannot be ignored.The stress can also greatly modulate the lattice field of the transition metal oxides.Profound physical problems such as coulon,John-Teller effect,coexistence and competition of double exchange and super exchange can also be designed to degenerate the energy band through the modulation of stress,thereby modulating the occupation and conductivity of specific electrons,Strive to use this modulating power to seek means and methods to improve the efficiency of hydrogen evolution.In addition,in the flexible system,manganese oxide has 100% spin polarization,and its cruising electrons can be qualitatively characterized by the magnetic information of the material,which is of great significance for understanding and finding active sites.Secondly,the valence state of Mn is rich,and it is expected to understand the charge transfer process of transition group metal oxides in the electrocatalysis process based on the multivalent state of Mn.Based on this,we mainly study the perovskite structure manganese oxide from the inside and outside.1.Inside: Study on the influence of perovskite oxide film growth process on its physical propertiesPLD was used to prepare a series of perovskite-type oxide thin-film catalysts,and the oxygen vacancy and crystal lattice were adjusted by adjusting the film growth environment,including the selection and processing of substrates,buffer layer preparation and sample preparation process Wait.Studies have shown that when the perovskite-type oxide film increases with oxygen pressure,the roughness increases and the particle size increases.Secondly,the electrocatalysis results show that the LSMO film has good catalytic activity in both oxygen-deficient and oxygen-rich environments.When the ratio of Mn3+/Mn4+ is fixed under moderate oxygen conditions,the catalytic efficiency has a minimum value,which proves that VO,Mn4+ are all catalytically active sites.The magnetic measurement results show that with the increase of oxygen pressure,the saturation magnetization and Curie temperature increase first and then decrease.There is an optimal growth oxygen pressure of 200 m T.At this time,the Curie temperature is about 370 K.2.External: Study on the influence of external stress on the electrocatalysis and magnetic properties of perovskite oxidesUsing the perovskite-type oxide La_0.7Sr_0.3MnO₃ as the model compound,a flexible heterostructure based on the thin film manganate epitaxially grown on the flexible mica substrate was prepared by the PLD method.The effect of different stresses on the lattice structure,magnetic properties and electrocatalytic properties of LSMO thin films was investigated by bending samples.Compared with the traditional substrates using rigid substrates for electrocatalytic devices,the flexibility combined with flexible substrates can show Give more competitive advantage.The experimental results show that during the repeated bending of the substrate for multiple cycles,the magnetic properties are almost the same under different bending states,no large-scale changes in magnetic interaction are seen,and the exchange type and strength are basically unchanged.And the study found that the CFO buffer layer thickness is greater than the critical thickness of 50 nm will reduce the saturation magnetization of the heterostructure,but at the same time can also increase the coercive force.The measurement results of electrocatalysis showed that with the increase of curvature,the hydrogen evolution reaction activity of the catalyst showed a continuous decrease in potential and an increase in current density.