Ultrasensitive Carbon Monoxide Sensor Based on a Silver Grating Coated by a Single Layer of Palladium Chloride at Room Temperature

We introduce a sensitive carbon monoxide (CO) sensor based on a layer of palladium chloride dihydrate PdCl _2 · 2H _2 O (PCD) which can work at room temperature. The core part of the sensor is a plasmonic grating coated by single-layer PCD. When CO molecules hit on PCD which will change into palladium (Pd), the reflectivity of the grating will change a lot. First-principles calculations and finite-difference time-domain methods are employed to calculate the dielectric constant of PCD and the reflection spectra, respectively. Our results show that the maximum difference of the reflection spectra between before and after reactions ( Δ R=R_PCD-R_Pd ) reaches 20