Ultrasensitive carbon monoxide detector based on palladium chloride hole array in a silver film at room temperature

We introduce a plasmonic carbon monoxide (CO) detector working at room temperature involving the dihydrate and palladium chloride (PdCl _2· 2H _2 O, PCD). A hole array in a silver film is filled by PCD. When CO meets our proposed structure, PCD turns to the palladium (Pd). Finite-difference time-domain methods are employed to calculate the absorption spectra, respectively. Our results show that the maximum of the difference of these two absorption spectra before and after reactions ( Δ A=A_Pd-A_PCD ) reaches to 40 percent in certain conditions. Surface plasmon polaritons provide a strong interaction between materials in the holes (PCD and Pd) and Ag hole array. We also explore the impacts of the size of the hole array on the efficiency of CO sensor. For applications at 273 k and 101 kPa, the structure with the period of 600 nm, the height of 300 nm, the size of the hole 300 nm × 240 nm, 1000 units is used to detect CO. If all PCD with the molecular size of 0.216 nm ^3 turn to be Pd, the concentration of CO in the testing gas is no less than 3.37 × 10^-3 ppm. Our proposed structure is quite useful and has potential applications in safety productions, food safeties and other fields.