Detection Principle of CO Electrochemical Sensor for Gas Detector
The electrochemical carbon monoxide gas sensor adopts a closed structure design, which is composed of electrodes, filters, breathable membranes, electrolytes, electrode leads (pins), shells, and other parts.
The carbon monoxide gas sensor is used in conjunction with the alarm and is the core detection component in the alarm. It is based on the principle of constant potential electrolysis. When carbon monoxide diffuses into the gas sensor, its output terminal generates a current output, which is provided to the sampling circuit in the alarm, playing a role in converting chemical energy into electrical energy. When the gas concentration changes, the output current of the gas sensor also changes proportionally. The intermediate circuit of the alarm converts and amplifies the output to drive different execution devices, completing the detection and alarm functions of sound, light, and electricity. Together with the corresponding control device, it forms an environmental detection or monitoring alarm system.
When carbon monoxide gas diffuses onto the surface of the working electrode through the pores on the outer shell and the breathable membrane, it undergoes oxidation on the working electrode under the catalytic action of the working electrode. The chemical reaction formula is:
CO+H2O→CO2+2H++2e-
The H+ions and electrons generated by the oxidation reaction on the working electrode are transferred to the counter electrode at a certain distance from the working electrode through the electrolyte, and undergo a reduction reaction with oxygen in the water. The chemical reaction formula is:
1/2O2+2H++2e-→H2O
Therefore, a reversible oxidation-reduction reaction occurs inside the sensor. The chemical reaction formula is:
2CO+2O2 →2CO2
This reversible oxidation-reduction reaction always occurs between the working electrode and the counter electrode, and generates a potential difference between the electrodes.
However, due to the polarization of the electrodes caused by reactions occurring on both electrodes, it is difficult to maintain a constant inter electrode potential, which also limits the detectable range of carbon monoxide concentration.
