## 3 Results
### Final Product Analysis by FTIR  
In order to get further information about NO abatement, the final products in the two reactors were identified by FTIR. Figure 4 showed the FTIR spectra of the final products for NO abatement in TM-DBD and CC-DBD reactors when N\({}_{2}\) was taken as the buffer gas. The results showed a decrease behavior for NO abatement in two reactors except for the peak intensity. Figure 4: FTIR spectra of the final products for NO abatement (NO concentration was 345 ppm, and buffer gas was N\({}_{2}\)). Figure 3: Destruction and removal efficiency (DRE) of NO and NO\({}_{x}\) in TM-DBD and CC-DBD reactors under different O\({}_{2}\) concentration. Compared with the untreated gas, the intensity of NO absorption decreased after discharge in all reactors. The peak of N\({}_{2}\)O increased in CC-DBD, but it decreased in TM-DBD. Based on the facts, the final products of NO abatement included N\({}_{2}\)O in CC-DBD. In addition, the peak intensity of NO and N\({}_{2}\)O in TM-DBD correspondingly became weaker than them in CC-DBD. The results indicated that the electrode structure of TM-DBD was better for abatement of NO and NO\({}_{x}\) under low O\({}_{2}\) concentration. Figure 5 showed the FTIR spectra for NO abatement with 345 ppm NO under the buffer gas of 8% O\({}_{2}\) and 92% N\({}_{2}\) in the TM-DBD and CC-DBD reactors. Compared with the untreated gas shown in Figure 4, the peak intensity of NO\({}_{2}\) and N\({}_{2}\)O with the peaks at 2200 cm-1 and 1600 cm-1 all increased obviously in the two reactors. The results indicated that the final products in the TM-DBD and CC-DBD reactor included few N\({}_{2}\)O (about 9.9 \(\times\) 10\({}^{-3}\) ppm) and NO\({}_{2}\), respectively. According to Figure 5, there was still quite a peak intensity of NO in TM-DBD reactor while NO was almost not identified in the CC-DBD reactor; moreover, the intensity of NO\({}_{2}\) and N\({}_{2}\)O absorption in TM-DBD was higher than that in CC-DBD. The difference between TM-DBD and CC-DBD was ascribed to the conclusion that the DRE of NO as well as NO\({}_{x}\) was better in CC-DBD reactor under high O\({}_{2}\) concentration. To explore the difference of above experiment results, the mixture of 92% N\({}_{2}\) and 8% O\({}_{2}\) without NO was induced into the TM-DBD and CC-DBD reactors. Figure 6 showed the FTIR spectra of the final products produced in the TM-DBD and CC-DBD reactors, respectively. It can be seen that NO, NO\({}_{2}\) and N\({}_{2}\)O were identified with the peaks at around 1900, 1600 and 2200 cm-1 in TM-DBD reactor, while the final product was only O\({}_{3}\) with the peak at around 1000 cm-1 in the CC-DBD reactor. The different results indicated that N\({}_{2}\) was dissociated by electron impact dissociation reactions in TM-DBD reactor, namely, e+N\({}_{2}\)\(\rightarrow\)e+2N and N would recombine with O and O\({}_{2}\) to produce new NO\({}_{x}\) in the TM-DBD reactor, which also verified the results of the final products shown in Figure 5. O\({}_{2}\) dissociation could  
Figure 5: FTIR spectra of final products for NO abatement in TM-DBD and CC-DBD reactor (NO concentration was 345 ppm; buffer gas was 8% O\({}_{2}\) and 92% N\({}_{2}\)). occur in TM-DBD but O\({}_{3}\) was not detectable, because it is selectively consumed by NO. However, in the CC-DBD reactor, only the identification of O\({}_{3}\) production was determined and no evidence of N\({}_{2}\) dissociation reactions could be seen. Above all, NO abatement was performed mainly through the reduction channel in the TM-DBD and CC-DBD reactors under low O\({}_{2}\) concentration, and moreover, the electrode structure of TM-DBD was preferable. However, When O\({}_{2}\) concentration increased, O\(\cdot\) produced by the dissociation of O\({}_{2}\) in reaction system rapidly enhanced and the channel of oxidation reaction was predominant. The new NO\({}_{\times}\), generated from the reaction of N+O\(\rightarrow\)NO, N+O\({}_{2}\rightarrow\)NO+O, and NO+O\(\rightarrow\)NO\({}_{2}\)[21] cannot be ignored in the TM-DBD.