富表面氧空位Fe2O3/ZnO催化剂在光催化合成氨中的应用

光催化合成氨是一种绿色节能的合成氨技术,设计制造丰富的表面氧空位和异质结构是促进氮分子活化和抑制电子-空穴复合的重要方法。我们以乙二醇作为还原剂,采用溶剂热法制备合成了Fe2O3/ZnO光催化剂,利用X射线衍射(XRD)、透射电镜(TEM)、电子顺磁共振(EPR)、紫外-可见漫反射(UV-Vis DRS)、荧光光谱(PL)及光电流(PC)对Fe2O3/ZnO催化剂进行表征,并考察了Fe2O3/ZnO催化剂在常温、常压下的光催化合成氨的性能。4%Fe2O3/ZnO催化剂在无牺牲剂下用于光催化合成氨,有较好的光催化效率和稳定性,其合成氨效率达到2059μmol·L-1·g-1·h-1。其高催化效率归因于:可见光区域吸收的提高、氮分子在表面氧空位与Fe3+活性中心上的协同活化及光生电子与空穴的高分离效率。

Photocatalytic Synthesis of Ammonia over Fe2O3/ZnO with Rich Surface Oxygen Vacancy

Photocatalytic synthesis of ammonia is a sustainable and energy-saving synthetic ammonia technology.Rich oxygen vacancies and heterostructures are important to increase the photocatalytic nitrogen to ammonia.We synthesized Fe2O3/ZnO nanocomposites by solvothermal method using ethylene glycol as the reducing agent.X-ray diffraction(XRD),transmission electron microscopy(TEM),electron paramagnetic resonance(EPR),UV-Vis DRS,photoluminescence(PL)and photocurrent(PC)were used to characterize the Fe2O3/ZnO catalysts.The performance of photocatalytic synthesis of ammonia by Fe2O3/ZnO catalysts was tested at room temperature.The results show that heterostructure was formed between ZnO nanorods and Fe2O3 nanoparticles while abundant surface oxygen vacancies were produced over the Fe2O3/ZnO catalysts.Fe2O3 nanoparticles not only provide rich N2 chemical adsorption sites,but also promote the light absorption of ZnO in the visible region.The introduction of Fe2O3 reduces the concentration of bulk oxygen vacancies and inhibits the recombination of photogenerated electrons and holes.The 4%Fe2O3/ZnO catalyst exhibited enhanced photocatalytic nitrogen fixation efficiency with a NH3 rate of 2059μmol·L-1·g-1·h-1 with better stability.The high catalytic efficiency is attributed to the enhancement of visible light absorption,the activation of nitrogen molecules on surface oxygen vacancies and Fe3+active sites,and the high separation efficiency of photogenerated electrons and holes.