Such observations indicate that N2O formation might occur predominantly in the gas phase and is promoted with the presence of sea water vapor. Noticeably, NHx-assigned peak at 336.1 nm was well-detected from the plasma catalyst processes with N2/H2 and N2/sea water vapor while it is not visible for the plasma-only process with N2/sea water vapor (Fig. ). This result validates the absence of ammonia product from N2/sea water vapor over the plasma-only route as discussed previously. In addition, plasma-activated nitrogen species exist in the form of vibrational and rotational excitation, electronic excitation, and ionization without minimal dissociation observed (Fig. ). Noticeably, the OES spectrum collected from the ammonia synthesis reactions over the Co/SiO2 catalyst (Fig. ) displayed the presence of N2O, similar to the one obtained over the SiO2 catalyst. Meanwhile, nitrous oxides were not detected from the reaction over the Ag/SiO2.