High-performance Ce doped three-dimensional ordered macroporous Co-based catalysts on CO oxidation

Abstract

A series of Co₃O₄ and Co_xCe₁O_y catalysts were successfully prepared by a colloidal crystal template method, and various characterization results confirmed the formation of a three-dimensional ordered microporous (3DOM) structure and Ce doping into the lattice of Co₃O₄. The catalytic activity of the prepared catalysts was measured on CO oxidation. Compared with a bulk catalyst, 3D-Co₃O₄ and 3D-Co_xCe₁O_y were more favorable for CO diffusion and had the advantage in terms of contact state with CO. In addition, XPS and d-band center results demonstrated that Ce doping regulated the valence states of Co ions and produced more Co³⁺ with stronger oxidation capacity, enhancing the intrinsic activity. Meanwhile, the DFT calculation of the adsorption energy for O₂ and CO showed that 3D-Co₁₆Ce₁O_y could easily utilize O₂ and adsorb CO preferentially. Under the synergistic promotion of the 3DOM structure and Ce doping, 3D-Co₁₆Ce₁O_y has the best catalytic activity performance (T₅₀ = 124.8 °C) and the lowest activation energy (E_a = 95.85 kJ mol⁻¹). Besides, the stability test showed that the catalyst has good thermal stability. Therefore, the combined improvement in morphology and intrinsic activity has a bright prospect for the synthesis of high-performance CO oxidation catalysts.