and copper mesh grounding. The inner electrode was made of tungsten, and it was placed at the center of the quartz tube. For each experiment, 100 mg of catalyst in fine powder form was packed in the center of the quartz tube reactor. Quartz frits were placed at the input and output of the reactor to prevent any possible catalyst displacement under the gas flow. To ensure that all ammonia was captured, the gas was bubbled in deionized water. The reactor exhaust was connected directly to an Agilent 8860A GC operating with a HP-PLOT U column (30 m × 0.32 mm × 10 μm) with hydrogen gas as a carrier. The light emitted from the discharge was led through an optical system. The measurements were recorded using a dual channel UV-vis-NIR spectrophotometer (Avantes Inc., USB2000 Series) in a scope mode. The spectral range was from 200 to 1100 nm, using a line grating of 600 lines/mm and a resolution of 0.4 nm. A bifurcated fiber optic cable of 400 μm was employed. Acceptance angle and location: emission spectra of the glow region were measured at the center of the tube since the catalyst was packed in the center of the tube. The fiber optical cable was positioned at the center of the reactor, and the distance between the reactor and fiber optical cable was 7 cm, consistent throughout the collection. The UV-vis-NIR spectrophotometer focuses the exit light under 90°. Standard optical fibers have a numerical aperture of 0.22 and an acceptance angle of 25°. Cu/SiO2 catalysts verified the respective metallic content was 3.02, 3.10, and 3.04%, respectively. The Raman spectrum was collected from 1000 -3500 cm -1 wavelengths for all catalyst samples (Fig. ). The peak at 1000 to 1300 cm -1 are associated with Si while the peaks at 1500 -1600 cm -1 are assigned to the photoluminescence of interstitial oxygen from atmospheric air in the interparticle space, respectively. Such interstitial oxygen lead to the formation of a Frenkel defect pair (Si-Si bond and interstitial oxygen atom, O) by dense electronic excitation. There are unknown peaks appearing between 2500 and 3000 cm -1 . These bands appear with the laser excitation (𝜆exc) at 514.5 nm possibly due to either linearly coordinated resonance phenomena or the presence of small amounts of carbon, derived from organic surfactants employed during catalyst preparation, attributed to incomplete removal after calcination in air. Catalytic activity. We studied the catalytic performance by screening the ammonia synthesis rate (𝑟 𝑁𝐻 3 ) over plasma-driven ammonia synthesis from N2/sea water vapor with various N2 flowrates i.e., 3.1, 6.2, 12.5, and 25.0 sccm and plasma powers (2, 3, 5, and 6 W) in the absence of catalyst and ammonia was not detected. In contrast, an ammonia synthesis rate (𝑟 𝑁𝐻 3 ) of 0.8 mmol.gcat -1 .h -1 was obtained from a N2/H2 mixture at similar testing conditions (N2 flowrate was 12.5 sccm and H2 flowrate was fixed at 12.5 sccm, plasma power of 2 W), which is consistent with our previous studies . This result provides evidence that a catalyst is required for ammonia production from N2 and sea water vapor. The observed ammonia synthesis rate (𝑟 𝑁𝐻 3 ) produced from N2/sea water vapor mixture at different flowrates and plasma powers over the silica sphere catalyst is shown in Fig. . The ammonia synthesis rate obtained from the N2/H2 system (H2 flowrate fixed at 12.5 sccm, is shown in (Fig. )