Towards Understanding Photocatalytic Plasma Reforming of Methane to Syngas Using a TiO2-Coated DBD

The urgency to achieve global carbon neutrality has reignited interest in plasma reforming of methane and carbon dioxide. Despite active efforts that have been recently made with various types of plasma reforming, by standalone or by combining with other means (e.g., metal oxide catalysts such as TiO
2
), the method still trails behind other promising technologies from the aspect of efficiency. Furthermore, a critical gap remains in our comprehension of the synergistic mechanisms underlying plasma-catalyst interactions. In this study, we investigate the photocatalytic reforming of methane using a TiO
2
-coated dielectric barrier discharge (DBD), with a focus on elucidating the physical and chemical influences of plasma. Optical emission spectroscopy was employed to obtain plasma characteristics, while a mass spectrometer facilitated the quantitative analysis of methane reforming. Our investigation is structured in two pivotal case studies as follows. First, the introduction of ozone with oxygen has a chemical effect on charge carrier generation activating methane adsorbed on the TiO
2
surface. Notably, ozone addition appears to mitigate coking on electrodes near the discharge zone, which otherwise diminishes the operational lifespan of TiO
2
. The second case study was designed to reveal the role of high-energy electrons on TiO
2
activation. For this, a cold helium plasma jet impinging on the TiO
2
-coated electrode was added to the system. We believe the insights garnered from this study advance our understanding of the intricate dynamics within plasma-catalyst systems for methane reforming, highlighting both novel contributions and ongoing challenges.