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Updated: May 16, 2025
10:57
Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction
Published on: April 10, 2018
18.1K
Self-assembled nickel(II)-centered metal-organic square grid complexes for CO2 sensing
M Sooraj1, R Jayakrishnan2, E Manoj1
1Department of Applied Chemistry, Cochin University of Science and Technology, Kochi, Kerala 682022, India. manoje@cusat.ac.in.
Dalton Transactions (Cambridge, England : 2003)
|April 2, 2025
Summary
New metal-organic square complexes show promise as sensitive carbon dioxide (CO2) gas sensors. These thin-film sensors, particularly complex 2, demonstrate enhanced detection capabilities, even under illumination, offering improved environmental monitoring solutions.
Area of Science:
- Materials Science
- Supramolecular Chemistry
- Environmental Science
Background:
- Detection of hazardous carbon dioxide (CO2) gas is critical for human health, environmental safety, and achieving UN Sustainable Development Goals (SDGs).
- Metal-organic frameworks and coordination complexes are increasingly explored for gas sensing applications due to their tunable structures and properties.
Purpose of the Study:
- To investigate novel Ni(II) metal-organic square grid complexes as thin-film CO2 gas sensors.
- To synthesize and characterize two new Ni(II) complexes, [Ni(HL)]4Cl4·26H2O (1) and [Ni(HL)]4(BF4)4·20H2O (2), using a thiocarbohydrazone ligand (H2L).
- To evaluate the CO2 sensing performance of thin films fabricated from these complexes.
Main Methods:
- Self-assembly synthesis of Ni(II) metal-organic square grid complexes.
- Structural characterization using single crystal X-ray diffraction (SCXRD) and MALDI mass spectrometry.
- Thermal stability analysis (thermogravimetric study) and pore volume determination (BET surface area).
- Fabrication of thin-film sensors via drop casting and evaluation of CO2 sensing performance in chemiresistive mode, with and without white light illumination.
Main Results:
- Two stable Ni(II) metallosupramolecular square grid complexes (1 and 2) were successfully synthesized and characterized.
- Complex 1 exhibited a solvent accessible pore volume of 1952 Å3 (≈18.2%) and a BET surface area of 2.390 m2 g-1.
- Complex 2 showed a higher BET surface area (4.803 m2 g-1) and semiconductor characteristics with a band gap of ~1.45 eV.
- Both complexes demonstrated CO2 gas sensing capabilities, with complex 2 showing a response of 59% compared to 31% for complex 1.
- CO2 sensing performance was enhanced under white light illumination, and complex 2 achieved a limit of detection of 500 ppm.
Conclusions:
- The synthesized Ni(II) metal-organic square complexes are stable and possess semiconductor properties suitable for gas sensing.
- Thin films of these complexes, particularly complex 2, function effectively as chemiresistive CO2 gas sensors.
- The developed CO2 gas sensors show improved performance under illumination, with complex 2 offering superior sensitivity and a low limit of detection.
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