In terms of materials, the Co/SiO2 catalyst also exhibited the highest ammonia production rate at all testing conditions (Fig. ). This can be attributed to the lower binding energy of Co with nitrogen relative to the Ag and Cu . Other researchers have also indicated that metals having stronger nitrogen binding energy delivered lower ammonia synthesis rate due to slow N-H formation . Accordingly, the theoretical targeted ammonia synthesis yield for an ideal small scale ammonia synthesis process is 100 g NH 3 . kW -1 . h -1 , while the currently reported values employing N2/H2 are mostly below 20 g NH 3 . kW -1 . h -1 produced over noble catalysts i.e., Ru-based catalysts. Other catalysts such as Ni or Fe are reported to produce energy yield of below 1.0 g NH 3 . kW -1 . h -1 . In comparison with such reported works, the ammonia energy yield obtained from either N2/sea water vapor (3.2 g NH 3 . kW -1 . h -1 ) or N2/H2 system (5.6 g NH 3 . kW -1 . h -1 ) over the Co/SiO2 catalyst in this work displays a competitive performance and high potential for further optimizations. N2/H2 at different plasma powers and an input N2 flowrate of 6.2 sccm.