石墨烯量子点辅助合成Cu-MOFs及CO_(2)吸附行为

Synthesis and CO_(2) adsorptive storage of Cu-MOFs by graphene quantum dots-assistant route

选用一种成本低、可大规模合成的Cu基MOFs(Cu-MOFs)材料作为CO_(2)吸附剂,在原位合成过程中添加石墨烯量子点以调控其晶体结构.结果表明:适量石墨烯量子点的添加有利于提高Cu-MOFs的比表面积和孔体积,相比未改性MOFs材料,改性后的CO_(2)吸附性能有所提高,25℃,100kPa时提高了4.5%.随着温度升高,吸附容量提升越明显.改性后的MOFs对于N_(2)的吸附量则比未改性时更低,因此计算得到的CO_(2)/N_(2)吸附选择性也更高,增加了近一倍.综合等量吸附热的考察结果发现,尤其添加适量含N石墨烯量子点的Cu-MOFs吸附剂不仅具备了较高的吸附容量、吸附选择性,还展现了较理想的吸附热,因此兼具了较优CO_(2)吸附性能和较低脱附能耗的特点,为MOFs吸附剂的改性提供了一点参考价值.

In this paper,a kind of Cu-based MOFs which is low-cost and easy to be synthesized in large-scale was selected as the CO_(2) adsorbent.Graphene quantum dots(GQDs)were in-situ incorporated in the synthesis process of MOFs to control their crystal structure.The research results indicated that adding of a proper amount of GQDs was beneficial to increase the specific surface area and pore volume of Cu-MOFs.Compared with the pristine MOFs,CO_(2) adsorption capacities of the modified MOFs were improved.At 25℃and 100kPa,the highest increased 4.5%.As temperature increased,the improvement of CO_(2) adsorption capacity was more obvious.The adsorption capacities of the modified MOFs for N_(2) were lower than that of the pristine MOFs,thus their calculated adsorption selectivity values of CO_(2)/N_(2) were higher and nearly doubled.Combined with the results of isosteric heats of CO_(2) adsorption,especially the Cu-MOFs adsorbent added with a proper amount of N-doped graphene quantum dots,which not only had higher CO_(2) uptake and selectivity,but exhibited more ideal adsorption heat within the physical adsorption category.Therefore,it has the characteristics of superior CO_(2) adsorption performance and low energy consumption for desorption,which provides a little reference value for the modification of MOFs adsorbent.