Water promoting effect in CO oxidation over N-doped Co3O4/Pt nanocatalysts by tailoring metal-support interfaces

The interfacial sites of metal-support catalysts are crucial for catalytic reactions. Herein, we designed well-defined N-Co3O4/Pt catalysts with N-tailoring metal-support interfaces to promote catalytic activity toward CO oxidation under humid environments. A series of N-Co3O4/Pt catalysts were fabricated using ZIF-67 nanocubes as self-sacrificing templates, which showed exceptionally high catalytic activity in low-temperature CO oxidation. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study indicates that H2O molecules undergo dissociative adsorption to form active -OH species (Co3+-OH-Pt). Isotopic labeling technique indicates that H2O molecules (or -OH groups) contribute to -65% of CO2 production in CO oxidation. Moreover, the amount of N dopant that stabilized the Co3+-OH-Pt species was highly dependent on the H2O-soaking conditions of ZIF-67/Pt. Density functional theory (DFT) calculations suggest that the COOH* pathway of CO oxidation over the N-Co3O4/Pt interface is energetically favorable in humid conditions. In particular, the N doping could stabilize the Co3+- OH-Pt interface and simultaneously reduce the energy barrier of CO2 formation from COOH* intermediates.