Trimesic Acid-Based Co(II) MOFs as Colorimetric Sensor for Detection of Ammonia Gas

The design of colorimetric sensing materials with low detection limits, and high stability are considered as important parameters in the development of ammonia (NH
₃
) sensors. In this research, we present a Metal-Organic Framework (MOF) based on Trimesic Acid and Co(II) (TMA-Co(II)) as the sensing material. The color detection of MOF upon exposure to NH
₃
was detected by Visible (VIS) fiber spectrometer, developed on the integrated circuit C12880MA of HAMAMATSU PHOTONICS, which is an integrated mini spectrometer operating in the spectral range between 340–850 nm. The activated TMA-Co(II) MOF demonstrated a limit detection of 60 ppm and the time of response ranged from 2 min to 12 min depending on the NH
₃
concentration. The sensor showed outstanding stability and reversibility in the cyclic test. It was easily recoverable by interaction with acid.