Pt/Cr2O3 Catalysts for the Reverse Water–Gas Shift Reaction: Unraveling Crucial Roles of Interfacial Synergy and Oxygen Vacancies

The development of high-efficiency platinum-based catalysts and the clarification of reaction pathways are fundamental challenges for a reverse water–gas shift (RWGS) reaction. Herein, we prepare a Pt/Cr₂O₃ catalyst with a 1% Pt weight loading using an impregnation method for the low-temperature RWGS reaction. This catalyst achieved high activity, selectivity, and long-term stability. At 350 °C and a space velocity of 24,000 mL h^–1 g_cat^–1, the catalyst achieved approximately 33.2% CO₂ conversion, nearing equilibrium conversion and much higher than Pt/Al₂O₃ and Pt/SiO₂. Pt species were highly dispersed on Pt/Cr₂O₃, existing in both Pt⁰ and Ptⁿ⁺ states, while the Cr species of the support primarily existed as Cr³⁺. Combined in situ experiments and density functional theory calculations revealed that the RWGS reaction on the Pt/Cr₂O₃ catalyst followed the carboxyl (COOH*) route: adsorbed CO₂ is hydrogenated through its O-end to produce trans-COOH*, which then converts to cis-COOH*, followed by the formation of CO via the dissociation of cis-COOH. The high activity of the Pt/Cr₂O₃ catalyst can be attributed to the interfacial synergy between Pt and Cr₂O₃ and the presence of oxygen vacancies. This work provides valuable insights into the design of high-performance catalysts for the RWGS reaction.