摘要
Due to the good controllability and high energy efficiency in adsorption processes,photoresponsive adsorbents are intriguing for CO2 capture.Nevertheless,most reported photoresponsive adsorbents are designed based on weak adsorption sites,regulating CO2 adsorption through structural change or steric hindrance.In addition,ultraviolet(UV)light is commonly involved in the regulation of adsorption capacity.Here we report for the first time the smart adsorbents for CO2 capture,which makes strong adsorption sites respond to visible(Vis)light.The adsorbents were fabricated by introducing primary amine and Dispersed Red 1(DR1,a kind of push-pull azobenzene that responds to Vis light rapidly)units to mesoporous silica,which act as strong adsorption sites and triggers,respectively.The primary amine sites make the adsorbents highly selective in the adsorption of CO2 over CH4.Without light irradiation,azobenzene is in the form of trans configuration,which leads to decreased electrostatic potential of primary amines and subsequently,exposure of active sites and liberal adsorption of CO2.Upon Vis-light irradiation,cis isomers are formed,which results in increased electrostatic potential of primary amines and subsequently shelter of active sites.Even on such strong adsorption sites,the alteration of CO2 adsorption capacity can reach 40%for the adsorbent with and without Vis-light irradiation.Moreover,the trans/cis isomerization of DR1 units can be triggered reversibly by Vis light.The present smart system endows adsorbents with selective adsorption capacity and avoids the employment of UV light,which is unlikely to be achieved by conventional photoresponsive adsorbents.
基于光响应吸附剂的吸附过程可控性好、能源效率高,其在CO2捕获中的应用受到关注.然而,大多数报道的光响应吸附剂是基于弱吸附位点设计的,通过其结构或位阻的变化控制CO2吸附.此外,还需要用到紫外光来调节吸附能力.本文首次报道了用于CO2捕获的智能吸附剂,促使强吸附活性位响应于可见光.吸附剂的制备通过将伯胺和分散红(DR1,一种响应于可见光的推-拉型偶氮苯)引入介孔氧化硅实现.伯胺作为强吸附位点促使吸附剂对CO2的选择性高于CH4,而DR1则作为控制开关.光照前偶氮苯处于反式构型,降低了伯胺的电势,因而实现了吸附位点的暴露和CO2的自由吸附.偶氮苯在可见光的照射下转变为顺式结构,伯胺的电势提高,因而活性位点被遮蔽.即使是强吸附位点,吸附剂在光照前后对CO2的吸附量变化也可以达到40%.此外,DR1的反式/顺式异构可以通过可见光的控制实现可逆转变.本文报道的智能系统赋予了吸附剂选择性且避免使用紫外光,这对于传统吸附剂而言是难以实现的.
基金
the Excellent Young Scientists Fund from the National Natural Science Foundation of China(21722606)
the National Natural Science Foundation of China(21676138,21878149 and 21808110)
China Postdoctoral Science Foundation(2018M632295 and 2019T120419)。
作者简介
Qiu-Rong Wu received his MSc degree from Nanjing Tech University in 2019 under the guidance of Prof.Lin-Bing Sun.His current research interest focuses on the design and synthesis of photoresponsive adsorbents for CO2 capture.contributed equally to this work;Peng Tan is a postdoctoral research associate in Nanjing Tech University.He received his PhD degree from Nanjing Tech University in 2017 under the guidance of Prof.Xiao-Qin Liu and Prof.Lin-Bing Sun.His research interest focuses on the design and fabrication of functional nanoporous materials,including porous carbons,zeolites,mesoporous silicas,metal-organic frameworks,and stimuli-responsive nanoporous composites,as well as their applications in adsorption and separation.contributed equally to this work;Corresponding author:Lin-Bing Sun is a full professor in Nanjing Tech University.He received his PhD degree from Nanjing University in 2008 under the guidance of Prof.Jian Hua Zhu and Prof.Yuan Chun.From 2011 to 2012,he worked with Prof.Hong-Cai JOE Zhou as a postdoctoral fellow at Texas A&M University.His current research interests mainly focus on the syntheses of porous functional materials as well as their applications in adsorption and heterogeneous catalysis.(email:lbsun@njtech.edu.cn)。
