| Spinels have controllable composition,structure,valence and morphology.They have attracted great attention due to their potential applications in catalysis and electrochemical systems.However,due to their poor intrinsic activity,the catalytic performance of such materials is not good,and how to improve the catalytic performance is an urgent problem to be solved.In this paper,by selectively etching the materials,controlling the concentration of oxygen vacancies,the Mn-based spinel synthesized by hydrothermal treatment with subsequent calcination was used in high-efficiency electrocatalytic 5hydroxymethylfurfural(HMF)reaction and electrocatalytic methanol reactions.The main research contents are as follows:(1)An urchin-like spherical structure CuMn2O4 spinel was prepared by hydrothermal treatment with subsequent calcination.Successively,Cu ions were selectively etched by ammonia to increase the oxygen vacancy concentration.The phase and morphology were characterized by XRD,SEM,TEM,XPS,Raman and other characterization methods,The HMF electrocatalytic oxidation was used to evaluate its performance.The test results show that CuMn2O4 with urchin-like spherical structure that was treated by ammonia etching.for 40 min has superior electrocatalytic performance.The current density of 20 mA·cm-1 was achieved with only 1.31 V vs RHE potential.It had high HMF conversion rate(100%)and Faraday efficiency(98.4%).And in five consecutive cycles of constant potential electrolysis,the Faraday efficiency value obtained ranged from 92.5%to 98.4%,which shows that the catalyst has good electrocatalytic stability.(2)The NiMnO3 spinel with hierarchical nano-sheet spherical structure was prepared by the hydrothermal process with subsequent calcination.The dimethylglyoxime solution was used to selectively etch Ni ions to increase the concentration of oxygen vacancies.The phase and morphology were characterized by XRD,SEM,TEM,XPS and some other characterization methods.The methanol electrocatalytic oxidation was used to evaluate its performance.The material exhibits good electrocatalytic performance:only 1.63 V vs RHE potential was required to achieve a mass activity of 197.4 mA·mg-1,After 35000 s of reaction under chronoamperometry,the mass activity is still 149.2 mA·mg-1.The prepared catalyst had good electrochemical properties and stability. |
