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

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. H-2 temperature programmed reduction (H-2-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 H-2 binding energy calculations based on density functional theory. While the nanosheets did exhibit high CO2 conversion, 28% at 510 degrees C, we found that the iron oxide nanowires had the highest CO2 conversion, reaching 50% at 750 degrees C under atmospheric pressure. No products besides CO and H2O were detected.