Enhancing the Reaction of CO₂ and H₂O Using Catalysts within a Nonthermal Plasma

The direct conversion of emitted and captured carbon dioxide into usable fuels remains a significant challenge and is a key element in the transition to net zero. Herein, we examine the reaction of CO₂ and H₂O over Ni- and Cu-based catalysts combined with nonthermal plasma (NTP) technology. The catalysis under NTP conditions enabled significantly higher CO₂ conversion and product yield, which was almost six times higher than that of the plasma-only system. A maximum H₂ concentration of ∼2500 ppm was achieved for the Cu/ZSM5 catalyst at 17% CO₂ conversion. Comprehensive catalyst characterization together with the reaction performances reveals that Cu in a reduced state promotes both the CO₂ and H₂O conversion leading to H₂ formation. <i>In situ</i> diffuse reflectance infrared spectroscopy (DRIFTS) coupled with mass spectrometry (MS) analysis of the gas phase products confirms that CO is the major active species to drive the water gas shift reaction to form H₂ in addition to the direct CO₂ and H₂O interaction. It also explains how the different metal support interactions influence the CO adsorption and its interaction with water. Among the catalysts studied, ZSM5-supported Cu catalysts were found to be the most effective in facilitating the CO₂ and H₂O reaction to produce H₂.