Non-thermal plasma assisted catalytic water splitting for clean hydrogen production at near ambient conditions

The catalytic non-thermal plasma (NTP) reactors have been widely applied for various plasma-assisted reactions to improve performance owing to the existence of the synergistic effect between plasma and catalyst. Herein, for the first time, the catalytic NTP reactors were engaged for hydrogen production by water splitting to explore the catalyst role in performance improvement. A preliminary catalyst, Au/(TiO2/SBA-15) (SBA-15: Santa Barbara Amorphous-15), was used to conduct catalyst optimization by adjusting metal loading amount, TiO2 loading amount, catalyst support type and metal species. The optimized catalyst was with a formula of 0.2 wt.% Au/(10 wt.% TiO2/SBA-15) and its hydrogen production rate was high up to 1.03 mL min−1 with a 36.9% water conversion, which is 245% of the performance of the NTP reactor without catalyst packing. To explore the inherent factors affecting the catalyst performance, the surface properties of the catalysts, such as specific surface area, pore volume and water adsorption amount, were investigated and correlated with the catalyst performance. Based on these, a hypothetic reaction mechanism that emphasizes the importance of surface discharge is proposed and a catalyst design principle is drawn as a catalyst with large surface area and pore volume as well as a moderate H2O adsorption amount performs the best. In theory, chemical kinetics modelling of H2O/Ar plasma was conducted to figure out possible reaction pathways for hydrogen production. The application of catalyst in NTP-assisted water splitting presents a promising path for performance promotion.