The interaction of carbon monoxide to Fe(III)(salen)-PEDOT:PSS composite as a gas sensor

• PEDOT:PSS/Fe(III)(salen) composite thin film coated by spin-coating was used as sensitive material.
• PEDOT:PSS/Fe(III)(salen) composite thin film presented CO gas detection with good reproducibility and fast response–recovery time.
• Gas response increases with increasing the flow rate of the CO gas.
• Reversible PEDOT:PSS/Fe(III)(salen) sensor exhibits high response and best selectivity to CO gas at room temperature.
• Addition of Fe(III)(salen) increased the effective surface area for the absorption of CO compared to the polymer layer.

PEDOT:PSS/Fe(salen) composite thin films were coated on glass pieces with interdigitated Au electrodes by spin coating method for CO gas sensing application. The metal complex doped PEDOT:PSS film was experienced by some common atmospheric gases to examine its identification ability for CO gas detection. The highest response factor (ΔR/R0 × 100) and lowest response time were gained −31.32 ± 0.88% and 38 s, respectively. An optimum level of doping (0.1 wt.% of Fe(salen)) was established for the highest sensitivity. The results showed that the sensor response was reproducible (RD < 2%) and fast recovery (5 s) in dry atmosphere and room temperature. The Fe(salen)-doped PEDOT:PSS was well characterized by different techniques such as UV–vis and FTIR spectroscopy. In addition, the surface topography of Fe(salen) doped PEDOT:PSS film was investigated using AFM. The results of this study can be helpful in selecting appropriate procedure for utilizing PEDOT:PSS/Fe(salen) composite for effective gas sensing applications.