Rotating Gliding Arc Assisted Water Splitting in Atmospheric Nitrogen

Abstract

In this study, hydrogen production from water splitting in N2 using an atmospheric pressure rotating gliding arc plasma was investigated. The effect of input H2O concentration and total flow rate on the performance of the plasma water splitting process (e.g., H2 and O2 yield, H2 production rate, and energy yield of H2) was investigated. N2 showed a pronouncedly facilitating effect on the H2O splitting and H2 production process due to the reactions of the excited N2 species [e.g., electronically excited metastable N2(A)] with the H2O molecules. The maximum H2 production rate reached up to 41.3 μmols−1, which is much higher than that of other typical non-thermal plasmas (e.g., ~0.2 μmols−1 for a dielectric barrier discharge). Optical emission diagnostics has shown that in addition to the NO, N2, and N2+ that were observed in the pure N2 spectra, strong OH and NH emission lines also appeared in the H2O/N2 spectra. OH radical is considered as a key intermediate species that could contribute to the formation of H2, O2, and H2O2. The increase of the H2O concentration could lead to a continuous enhancement of the OH intensity. The rotational temperature of N2+ dropped drastically from 2875 ± 125 to 1725 ± 25 K with the addition of 1 % (mol/mol) H2O into the N2 plasma.