In this study, nitrogen fixation in the electrolyte was achieved by atmospheric pressure non-thermal plasma generated by a sinusoidal power supply (with an applied voltage of 10 kV and frequency of 33 kHz). Ammonia measurements on plasma exposed electrolyte at several working gas and purging gas conditions revealed that nitrogen plasma on the same gas environment is more favorable for plasma-assisted ammonia synthesis. In addition, photo-electrochemical water splitting was performed by irradiating UV light (316 nm) on a titanium dioxide semiconductor photo-anode to generate hydrogen donor in nitrogen reduction reaction. The amount of ammonia synthesized by this synergistic process of photo-electrochemical water splitting and nitrogen plasma is six times higher than that obtained by nitrogen plasma alone. An increase in the co-synthesized N O X concentrations and background contamination at reaction site reduces the ammonia synthesis rate and Faraday efficiency. However, the ammonia production efficiency was increased up to 72% by using a proton-exchange membrane which prevent the diffusion of oxygen evolved from water splitting into the plasma, and by reducing the axial distance between the plasma electrode and reaction site. The sustainable nitrogen fixation process reported herein can be performed at atmospheric pressure conditions without a direct input of hydrogen gas or any catalyst.

This work proposes an atmospheric pressure plasma jet operated by the injection of natural air. The conventional plasma jet has been modified by creating a small hole in the quartz tube. The small amount of argon gas flow inside the tube creates a pressure difference with the surrounding environment. By Bernoulli's principle, natural air is forced to penetrate inside the tube to equalize this difference. The operational range of this device exists for only low argon gas flow rates of 200–600 sccm at a specified value of applied voltage. Compared to the conventional plasma jet without a hole, the concentration of reactive nitrogen species is significantly increased due to the mixing of the surrounding air. In addition, the gas temperature of the device remains close to room temperature, suggesting its strong possibility for biomedical applications. This approach can be an initiation towards the commercialization of plasma jets by using natural air.

In this study, nitrogen fixation in water was achieved using an atmospheric pressure non-thermal nitrogen plasma jet generated by an AC driven source of 10 kV (peak) power supply with...

Despite possessing versatile properties and great potential for biomedical research, the number of studies on the application polydopamine-functionalized gold nanoparticles (Au@PDA NPs) remains infrequent due to their preparation procedure, which...

In this study, ammonia (NH3) vapor was added to an atmospheric pressure argon plasma jet generated by a sinusoidal power supply (with an applied voltage of 4 kV and frequency of 35 kHz) and it was analyzed by electrical, optical, and chemical probe measurements. A total gas flow rate of 1200 sccm under 2% flow rate of either water or ammonia solution at concentrations up to 0.75% mixed with 98% argon feeding gas. The dissipated power of the plasma jet estimated by voltage-charge plots was found to decrease continuously with increase in ammonia concentrations at a fixed applied voltage. The optical emission spectra inside the quartz tube obtained for the NH3 mixed plasma indicated the presence of nitrogen emission lines which were absent in the water only mixed argon plasma. Colorimetric measurements of hydrogen peroxide (H2O2) and nitrite () in plasma activated water (PAW) were performed at different consumed energy varied by plasma exposure time. The H2O2 concentration decreased to 4 ppm from 14 ppm, while the concentration simultaneously increased to 6 ppm from 1 ppm as the ammonia concentrations increased to 0.75% from 0% throughout 2.07  ×  103 joule energy consumption. We also analyzed the corresponding variation of pH values, in absence of ammonia, PAW leads to acidification but addition of small amount of ammonia in plasma is sufficient to make it alkaline. Additionally, we measured the hydroxyl (OH) radical density in gas and liquid phases by utilizing UV absorption spectroscopy and chemical probe method, respectively. OH radical density in both phases also decreased with the increase in the NH3 concentrations. Experimental results obtained from this experiment can be attributed to control H2O2 concentrations in the PAW via plasma-assisted nitrification.