Hard templating ultrathin polycrystalline hematite nanosheets: effect of nano-dimension on CO2 to CO conversion via the reverse water-gas shift reaction

Abstract

Understanding how nano-dimensionality impacts iron oxide based catalysis is central to a wide range of applications. Here, we focus on hematite nanosheets, nanowires and nanoparticles as applied to catalyze the reverse water gas shift (RWGS) probe reaction. We introduce a novel approach to synthesize ultrathin (4–7 nm) hematite nanosheets using copper oxide nanosheets as a hard template and propose a reaction mechanism based on density functional theory (DFT) calculations. Hematite nanowires and nanoparticles were also synthesized and characterized. H₂ temperature programmed reduction (H₂-TPR) and RWGS reactions were performed to glean insights into the mechanism of CO₂ conversion to CO over the iron oxide nanomaterials and were compared to H₂ binding energy calculations based on density functional theory. While the nanosheets did exhibit high CO₂ conversion, 28% at 510 °C, we found that the iron oxide nanowires had the highest CO₂ conversion, reaching 50% at 750 °C under atmospheric pressure. No products besides CO and H₂O were detected.