Promotional effect of N-doped CeO2 supported CoOx catalysts with enhanced catalytic activity on NO oxidation

•We prepared CoOx/N-doped CeO2 via a g-C3N4 decorated sol–gel method.•The CoOx crystallites were encapsulated by CeO2.•Compared to CoOx/CeO2, the N-doped samples showed better catalytic performance.

A series of neoteric CoOx/N-doped CeO2 catalysts were synthesized by partly substituting the lattice oxygen of CeO2 with nitrogen by a simple g-C3N4-modified sol–gel method and comprehensively characterized by XRD, H2-TPR, XPS, BET, TEM, TG, UV–vis DRS, PL, EIS, NO(O2)-TPD and EPR. The results demonstrated that: (1) The N-doped catalysts showed larger surface areas and pore volumes, which were favorable for the adsorption of reactant gas; (2) Replacing O with N could promote the reduction of resultant catalysts and assist cobalt oxide in changing the valence and the support in supplying the oxygen; (3) By a sol–gel method, the CoOx crystallites in these catalysts were encapsulated by CeO2 with only a small fraction of Co ions on the surface and strongly interacting with CeO2. Such structure maximized the interaction between CoOx and CeO2 in three dimensions, resulting in unique redox properties. Moreover, the prepared materials were evaluated in the selective catalytic oxidation of NO. The results showed that the N-doped materials exhibited higher catalytic activity than the un-doped one due to those physicochemical changes. An enhanced mechanism on the improvement of catalytic performance was proposed, and this could pave the way for the designed and synthesis of new highly catalytic activity catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (154 K)Download as PowerPoint slideThis research studied the N-doped CeO2 supported CoOx on the process of NO oxidation. The resulting catalysts were comprehensively characterized and the results showed that the N-doped catalysts exhibited higher catalytic activity than undoped one due to a series of physicochemical changes. An enhanced mechanism on the improvement of catalytic performance was proposed, and this could pave the way for the designed and synthesis of new highly catalytic activity catalysts.