ZIF-67-derived CoO (tetrahedral Co2+)@nitrogen-doped porous carbon protected by oxygen vacancies-enriched SnO2 as highly active catalyst for oxygen reduction and Pt co-catalyst for methanol oxidation

Fabrication of efficient catalyst/co-catalyst for enhancing methanol oxidation and oxygen reduction reactions (MOR/ORR) is the key to make direct methanol fuel cells more economical. Here, hierarchical [email protected] porous [email protected]2 ([email protected]@SnO2) polyhedrons are prepared as active catalysts for ORR and Pt supports/co-catalysts for MOR using zeolitic imidazolate frameworks-67 (ZIF-67). For ORR, [email protected]@SnO2-1 ([email protected]2·2H2O mass ratio of 1: 1) exhibits a more positive peak potential (0.82 V vs. RHE) than that of commercial Pt/C (10 wt.%). Outer SnO2 shells can prevent CoO cores (active tetrahedral Co2+) from corrosion during ORR. For MOR, [email protected]@SnO2-1 (5 wt.%) shows a much higher mass activity (1518 mA mgPt−1) than that of Pt/C (496.8 mA mgPt−1). High CO tolerance of [email protected]@SnO2-1 is attributed to strong metal (Pt)-metal oxides (SnO2) interactions, which facilitate adsorption of OH− on SnO2 to remove COads. Therefore, this study provides a strategy to enhance ORR/MOR performance by using hierarchically-structured catalysts/co-catalysts from ZIF templates.