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采用离子液体[Bmim]Br为溶剂,溶剂热后处理法制备了具有大比表面积和氮空穴的石墨相氮化碳催化剂。采用X射线衍射(XRD)光谱、扫描电镜(SEM)、氮气吸附、紫外-可见(UV-Vis)光谱、X射线光电子能谱(XPS)、荧光光谱(PL)、电子顺磁共振谱(EPR)、程序升温脱附(TPD)等分析手段对制备的催化剂进行了表征。结果表明经过溶剂热后处理的催化剂形貌由无规则的层状结构变为尺寸为30-40 nm的纳米颗粒,导致比表面积从8.6 m~2?g~(-1)增加到37.9 m~2?g~(-1)。从N_2-TPD、荧光光谱及密度泛函理论(DFT)模拟计算的结果得出,氮空穴不仅能捕获光生电子促进电子空穴的有效分离,还能吸附并活化反应物氮气分子。溶剂热处理后,增加的比表面积导致更多的氮空穴作为反应活性位暴露在催化剂表面,是固氮活性显著提高。本文还探讨了可能的反应机理。
Graphitic carbonitride carbon catalysts with large specific surface area and nitrogen vacancies were prepared by solvothermal post-treatment using ionic liquid [Bmim] Br as solvent. The microstructure and mechanical properties were characterized by XRD, SEM, N2 adsorption, UV-Vis, XPS, PL, EPR ), Temperature-programmed desorption (TPD) and other analytical methods were used to characterize the prepared catalyst. The results showed that the morphology of the catalyst after solvothermal post-treatment changed from a random layered structure to a nanoparticle size of 30-40 nm, resulting in a specific surface area increased from 8.6 m 2? G -1 to 37.9 m ~ 2? G ~ (-1). From the results of N 2 -TPD, fluorescence spectroscopy and density functional theory (DFT) simulation, it was found that nitrogen hole can not only capture the photogenerated electron but also promote the effective separation of electron hole, and also can adsorb and activate the reactant nitrogen molecule. After solvent heat treatment, the increased specific surface area led to more nitrogen vacancies as reactive sites exposed to the catalyst surface, which markedly increased the nitrogen fixation activity. This article also explored the possible reaction mechanism.