Unveiling the Mechanistic Significance of Reducibility and Lattice Oxygen Evolution in the Ce1–x–yZrxNiyO2−δ Catalyst for Methanol Electro-Oxidation

Ni-based catalysts have garnered significant attention as alternative materials for the methanol oxidation reaction with its interesting Ni2+/Ni3+ redox couple. Enhancing the challenging Ni2+ → Ni3+ oxidation process can further improve catalytic methanol oxidation. In this study, through structural and surface analyses, we demonstrate that the highly reducible CeO2–ZrO2 support in the Ce1–x–yZrxNiyO2−δ solid solution effectively facilitates the Ni2+ → Ni3+ oxidation process and the evolution of lattice oxygen during methanol oxidation. The presence of Ni3+ species along with the surface oxygen vacancy promotes the formation of –OOH surface intermediates, while the evolved lattice oxygen facilitates the oxidation of CO, resulting in improved CO tolerance and enhanced methanol oxidation activity in Ce1–x–yZrxNiyO2−δ catalysts.