Synthesis And Photocatalytic Activity's Study Of Defect Nano Magnesium Oxide

MgO has photocatalytic activity based on its surface intrinsic defect structure.Our group synthesised nano MgO with surface oxygen vacancies by solution-combusting method,but its photocatalytic activity was low.The surface oxygen vacancies based on the appropriate amount could not only broaden the light absorption range of the material to reduce the band gap width,but also increase the number of adsorbed oxygen on the surface of the material and promote surface hydroxylation to produce reactive oxygen species such as superoxide anion and hydroxyl radicals.In this paper,the concentration of oxygen vacancies on the surface was improved by surface modification and non-metallic element doping to improve its photocatalytic activity.Surface modification was performed with ammonia and ethylene glycol as modifiers to modify the surface of nanometer MgO to increase its surface oxygen vacancy concentration.The HRTEM results showed that the modified nano MgO mainly exposed{111} crystal faces.The surface oxygen vacancies are easier to form on the {111} crystal plane than the {200} crystal planes.The results of liquid-phase electron paramagnetic resonance spectroscopy,nitroblue tetrazolium chloride reduction reaction and capture agent experiments showed that the modified nanometer MgO could produce more superoxide anion reactive oxygen species.Nano MgO was doped with carbon and boron,which are non-metal elements with low electronegativity.The results showed that the doping of carbon and boron could inhibit the crystal growth of MgO,and reduced the band gap width of the MgO and caused red shift of the absorption edge of the light.Compared with pure nano-magnesia,the concentration of oxygen vacancies on the surface of doped magnesia increased,and the main active oxygen species were superoxide anion and hydroxyl radical.Therefore,under the same degradation conditions,the photocatalytic activity of the modified and doped nano MgO was significantly higher than that of unmodified and undoped nano MgO.