Plasma-driven redox mechanism in the reverse water–gas shift reaction over Ni–In intermetallic catalysts

Abstract

The reverse water–gas shift (RWGS) reaction has been recognized as a promising strategy for CO₂ valorization. However, it faces limitations due to low activity and poor CO selectivity at low temperatures. In this study, we report that plasma can effectively promote the low-temperature RWGS reaction over Ni–In intermetallic catalysts. The formation of the Ni–In intermetallic phases completely suppresses CH₄ formation and achieves 100% CO selectivity. Through in situ transmission infrared spectroscopy (TIR) and in situ X-ray absorption fine-structure (XAFS) analysis, we monitored the changes occurring on the catalyst surface during the plasma reaction. The interaction between redox-active sites present in the Ni–In intermetallic catalysts and plasma-activated species lowers the activation energy, thereby facilitating the RWGS reaction at low temperatures. This study offers fundamental insights into how plasma-activated species enhance catalysis and the underlying mechanisms of low-temperature activation in plasma catalysis.