Unveiling the Mechanistic Significance of Reducibility and Lattice Oxygen Evolution in the Ce_1–x–yZr_xNi_yO_2−δ Catalyst for Methanol Electro-Oxidation

Ni-based catalysts have garnered significant attention as alternative materials for the methanol oxidation reaction with its interesting Ni 2+ /Ni 3+ redox couple. Enhancing the challenging Ni 2+ → Ni 3+ oxidation process can further improve catalytic methanol oxidation. In this study, through structural and surface analyses, we demonstrate that the highly reducible CeO 2 –ZrO 2 support in the Ce 1– x – y Zr x Ni y O 2−δ solid solution effectively facilitates the Ni 2+ → Ni 3+ oxidation process and the evolution of lattice oxygen during methanol oxidation. The presence of Ni 3+ 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 Ce 1– x – y Zr x Ni y O 2−δ catalysts.