Research On The Mechanism Of Water Splitting For Hydrogen And Anodizing Reaction By Optimizing The Electronic Structure Of Spinel Oxides

Hydrogen energy is considered to be the most promising new clean energy to replace the fossil fuels.Water splitting for hydrogen is one of the most promising green technologies.Spinel-type oxide catalysts have received much attention in the field of electrocatalytic hydrogen production due to their unique performance characteristics.Optimizing the electronic structure of the active sites is the key factor for controlling catalytic performance.However,the conventional synthesis methods and regulation strategies have limited the ability to further regulate the electronic structure of catalysts.The introduction of external fields,such as light and magnetic fields,has gradually gained the interest of researchers.In addition,electrochemical synthesis using organic small molecules or biomass oxidation coupled with hydrogen production has become a new research direction.It not only effectively reduces the overpotential,but also generates high-value products,reducing the cost of hydrogen production.However,the mechanism of the complex multi-coordinate spinel structure catalyst remains to be explored,particularly whether there is commonality between aldehyde oxidation mechanisms.Hence,the spinel oxide catalysts were used for investigating the magnetic field HER and the biomass（glucose）oxidation as a replacement for the OER,respectively.The main research content is as follows:（1）In order to break the limit of the conventional catalyst regulation methods,a magnetic field was innovatively introduced into the synthesis process of（Ni,Zn）Fe₂O₄spinel catalysts.Under the influence of the magnetic field,the growth of nano-particles resulted in a nanowire-like structure.This may be due to the local solution concentration being supersaturated under the action of the Lorenz force on the magnetic metal particles,accelerating nucleation reactions.Furthermore,the nucleated nanoparticles were influenced by the magnetization force,causing them to grow in the direction of the magnetic force.The results show that the external magnetic field mainly affects the ferromagnetic Fe metal ions on the surface of the catalyst,thereby affecting the surface morphology of the catalyst and changing its microelectronic structure.In 1 M KOH solution,M-（Ni,Zn）Fe₂O₄ only requires 67 m V to achieve a hydrogen evolution current density of 10 m A cm^-2.When M-（Ni,Zn）Fe₂O₄ is used as both the cathode and anode to form a dual-electrode test system,a voltage of only 1.76 V is required to achieve a current density of 50 m A cm^-2,and this maintains high stability even after 10 hours.（2）The strategy of coupling aldehyde hydroxy small molecule oxidation instead of OER reaction with hydrogen production is an effective method for reducing the overpotential of water splitting.However,the catalytic mechanism of organic small molecules needs to be further explored.The copper-based inverse spinel（Cu Fe₂O₄）,mixed spinel（Cu Al₂O₄）,and normal spinel（Cu Co₂O₄）were synthesized by the solvothermal methods.The structure-performance relationship of catalytic active sites at the atomic level during aldehyde oxidation was study.Experimental results showed that under a potential lower than 1 V,Cu Fe₂O₄>Cu Al₂O₄>Cu Co₂O₄ in terms of electrochemical performance during glucose and various aldehyde biomass catalysis,indicating that the copper-based inverse spinel structure exhibited the best electrochemical performance in catalyzing aldehyde biomass solutions,followed by the mixed spinel structure,with both structures showing better performance than the normal spinel structure.This suggests that for the aldehydes oxidation,the octahedral center copper metal is the active center,and its activity is significantly higher than that of the tetrahedral center copper metal.This experiment provides a new idea for exploring the mechanism of biomass molecule oxidation.