Bimetallic Coordination in Two-Dimensional Metal–Organic Framework Nanosheets Enables Highly Efficient Removal of Heavy Metal Lead (II)

Abstract

Two-dimensional (2D) metal–organic frameworks (MOFs) have emerged as intriguing 2D materials because of their specific features of 2D morphology and designable skeletons, which have elicited great interest in environment remediation. In this work, 2D MOF nanosheets are fabricated via a mixed-solvent solvothermal method, and a regulation strategy of metal inorganic clusters on MOFs is used to construct two different 2D MOFs with monometallic and bimetallic coordination, that is, Ni-MOF and Ni/Cd-MOF. Binary metal coordination renders more crystal defects and vacancies in the framework; thus, compared to monometallic Ni-MOF, bimetallic Ni/Cd-MOF exhibits fewer layers (4∼5 layers), higher specific surface area, larger pore size, and higher surface electronegativity, which leads to its excellent adsorption removal for Pb2+, with higher adsorption rate and affinity, and superior adsorption capacity (950.61 mg/g, almost twice as high as that of monometallic Ni-MOF). Besides, the adsorption mechanism further confirmed that the carboxyl groups (−COO−) from organic linker on 2D MOFs serve as the main binding sites for Pb2+ coordination, and bimetallic Ni/Cd-MOF has more active −COO− sites for Pb2+ capture. Thus, the bimetallic Ni/Cd-MOF regulated by heterogeneous metal atoms shows promising application for highly efficient adsorption of heavy metal ions.

Morphology Control of Two dimensional (2D) Metal–Organic Framework Nanosheets via 1 nm Thick Hexagonal Hydroxide Nanosheets through Variable Reaction Parameters

“…𝜈 COsym and 𝜈 COasym for Ni-BDC MOF has appeared on 1580 and 1370 cm −1 (Δ𝜈 = 190 cm −1 ). [13,14] This signal started to be strong after the reaction time of 4 h. This observation is in strong agreement with PXRD data. Shape of all resultant products (P-NiMOF) was observed by FE-SEM (Figure S2d, Supporting Information).…”

The use of bimetallic metal–organic frameworks as restoration materials for pollutants removal from water environment

“…dyes) [20][21][22][23][24][25][26][27], pharmaceuticals or personal care products (PPCPs) [28][29][30][31][32][33][34] and inorganic pollutants (e.g. heavy metal ions) [17,[35][36][37][38][39] by adsorption or photocatalysis. They can also remove organic contaminants through oxidative degradation and incomplete mineralization, named Fenton reaction or Fenton-like reactions and persulfate (PS) oxidativation.…”

“…During the last decade, BMOFs have been explored extensively and exhibited high potential in removing pollutants in wastewater because of their high porosity, diverse compositions, adjustable pore structure and good stability [ 17 ]. In addition, the synergistic effect of the bimetallic sites gives the BMOFs the unique significant increase in acidity and reactivity [ 18 , 19 ].…”

A high valence binary metal–organic framework as an electrode material for aqueous asymmetric supercapacitors

“…For instance, these peaks shift from 730 cm À1 and 782 cm À1 in BDC to 738 cm À1 and 812 cm À1 in NiCo-BDC and 744 cm À1 and 811 cm À1 in Ni-BDC. [12][13][14][15] This shift signifies a decrease in the electron cloud density on the benzene ring of BDC and a substantial increase in vibration energy. Additionally, in the case of NiCo-BDC, bimodal vibration peaks around 410-480 cm À1 for Ni-O/Co-O bonds are observed, while Ni-BDC exhibits a unimodal peak for Ni-O bonds.…”