三维Cu-MOF对亚甲蓝的吸附和光催化降解及其机理

Adsorption,photocatalytic degradation,and their mechanisms of methylene blue on three⁃dimensional Cu⁃MOF

本文报道了[Cu_(3)(ppda)_(3)(tib)_(2)(H_(2)O)_(4)]·6H_(2)O(Cu-MOF)的合成、结构、吸附和光催化降解性能。在Cu-MOF中,1,4-苯二乙酸(H_(2)ppda)和1,3,5-三(1-咪唑基)苯(tib)配体交替连接Cu离子形成二维层,层与层之间通过trans-ppda^(2-)相互穿插形成稳定的三维结构。Cu-MOF对亚甲蓝(MB)的催化效率为97%,最高反应速率常数为0.0197 min^(-1)。光催化降解机理:在光的激发下,催化剂表面的光生电子和空穴对发生分离,并与O_(2)、H_(2)O、H_(2)O_(2)反应生成活性物质,将染料降解为CO_(2)和H_(2)O。在MB溶液中加入NaCl(200 g·L^(-1))后,Cu-MOF的吸附量有所提升(87.23 mg·g^(-1)),准二级动力学模型和Langmuir等温线模型的实验数据拟合程度较好,该吸附的主要过程为单层化学吸附。

Herein,we report the synthesis,structure,adsorption and photocatalytic degradation properties of a novel metal‑organic framework[Cu_(3)(ppda)_(3)(tib)_(2)(H_(2)O)_(4)]·6H_(2)O(Cu‑MOF)by the selection of the flexible 1,4‑phenylenediacetic acid(H_(2)ppda)and the rigid 1,3,5‑tris(1‑imidazolyl)benzene(tib).In Cu‑MOF,ppda^(2-)and tib ligands alternately link Cu ions to form 2D polymeric layers,the layer and layer interpenetrate each other by trans‑ppda^(2-)to form a stable 3D structure.Cu‑MOF has excellent thermal stability and semiconductor properties,so it can be used as a catalyst.Cu‑MOF had the best catalytic effect on methylene blue(MB),with a catalytic efficiency of up to 97%and the highest reaction rate constant of 0.0197 min^(-1).The main photocatalytic degradation mechanism is the separation of the photogenerated electron and hole pair of the catalyst under the light excitation,and the redox reaction occurs to produce the active species to degrade the dye and eventually decompose into carbon dioxide and water.Cu‑MOF exhibited high adsorption capacity after adding NaCl(200 g·L^(-1))to MB solution(87.23 mg·g^(-1)).The adsorption process is a spontaneous monolayer chemisorption process illustrated by the pseudo‑second‑order kinetic and Langmuir isotherm models and thermodynamic studies.CCDC:2219373.