Atomically Dispersed Ru/Feox Catalyst with High Performance for Water Gas Shift Reaction

Single-atom catalysts (SACs) possess high activity and selectivity for water gas shift (WGS) reaction. Herein, a series of iron oxide supported ruthenium catalysts (Ru/FeOx) loaded with either Ru single-atoms (Ru/FeOx SACs) or Ru nanoparticles (Ru/FeOx NPCs) have been prepared by coprecipitation method. Ru/FeOx SACs obviously exhibit high CO conversion and completely suppress methanation side reaction due to numerous oxygen vacancies, weak CO adsorption and no H2 dissociation on Ru single-atoms. The large number of oxygen vacancies were found to promote the dissociation of H2O to form H2 and atomic O, and the atomic O subsequently reacts fast with linearly adsorbed CO on Ru single-atoms through an associative process with an activation energy as low as 71.00 kJ/mol when compared with Ru/FeOx NPCs. As a result, the specific activity of Ru/FeOx SAC with a Ru loading as low as 0.05 wt.% is 6.4-fold higher than that of RuNP/FeOx NPC with a Ru loading of 1.3 wt.%. Aberration-corrected high angle annular dark-field scanning transmission electron microscope (AC-HAADF-STEM) and in situ diffuse reflectance infrared Fourier-transform spectroscopy (in situ DRIFTS) have been employed to analyze the catalysts. The results indicate that Ru/FeOx SACs represent one of the most excellent catalysts reported so far.