Bimetallic MOF-Based Sensor for Highly Sensitive Detection of Ammonia Gases

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Growing demand for detecting ultralow concentrations of ammonia gas.
• Need for sensitive, stable, and room-temperature ammonia gas sensors.
• Limitations of traditional ammonia detection methods.

Purpose of the Study:

• To develop a highly sensitive and stable capacitive sensor for ultralow ammonia gas detection.
• To synthesize and characterize a bimetallic metal-organic framework (MOF) based on Prussian blue analogs (PBAs).
• To investigate the ammonia adsorption efficiency and sensing performance of the developed material.

Main Methods:

• Synthesis of a copper-iron bimetallic metal-organic framework (Cu-Fe PBA) using a cation-exchange strategy.
• Fabrication of a capacitive sensor with a Cu-Fe PBA sensitive membrane and interdigitated electrodes (IDEs).
• Characterization using quartz microcrystal balance (QCM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis.

Main Results:

• The Cu-Fe PBA exhibited enhanced ammonia adsorption capacity (2.2 mmol g⁻¹ at 10 ppm).
• Introduction of Cu²⁺ increased the specific surface area and ammonia adsorption sites while maintaining the PBA structure.
• The capacitive sensor demonstrated a linear response from 75-1000 ppb and a low detection limit of 3.8 ppb for ammonia.

Conclusions:

• The developed Cu-Fe PBA-based capacitive sensor offers superior performance for ultralow ammonia detection.
• The material shows excellent stability and sensitivity at room temperature.
• The sensor has significant potential for practical applications in ammonia gas monitoring.