Testing of Sr-Doped ZnO/CNT Photocatalysts for Hydrogen Evolution from Water Splitting under Atmospheric Dielectric Barrier Plasma Exposure

Abstract

Nonthermal plasma is a well-recognized environmentally advantageous method for producing green fuels. This work used different photocatalysts, including PZO, SxZO, and SxZCx for hydrogen production using an atmospheric argon coaxial dielectric barrier discharge (DBD)-based light source. The photocatalysts were produced using a sol-gel route. The DBD discharge column was filled with water, methanol, and the catalyst to run the reaction under argon plasma. The DBD reactor was operated with a 10 kV AC source to sustain plasma for water splitting. The light absorption study of the tested catalysts revealed a decrease in the band gap with an increase in the concentration of Sr and carbon nanotubes (CNTs) in the Sr/ZnO/CNTs series. The photocatalyst S25ZC2 demonstrated the lowest photoluminescence (PL) intensity, implying the most quenched recombination of charge carriers. The highest H2 evolution rate of 2760 μmol h-1 g-1 was possible with the S25ZC2 catalyst, and the lowest evolution rate of 56 μmol h-1 g-1 was observed with the PZO catalyst. The photocatalytic activity of S25ZC2 was initially high, which decreased slightly over time due to the deactivation of the photocatalyst. The photocatalytic activity decreased from 2760 to 1670 μmol h-1 g-1 at the end of the process.