Boosting electrocatalytic oxygen reduction performance of Co[sbnd]N[sbnd]C catalysts on Ti3C2 MXene by the synergistic effect with oxygen vacancy-rich TiO2.

[Display omitted] • Ti 3 C 2 supported Co N C and oxygen vacancy-rich TiO 2 (ov-TiO 2) composite is synthesized. • 20–60 nm TiO 2 nanoparticles with oxygen vacancies in-situ grow on Ti 3 C 2 nanosheets. • The synergistic effect of ov-TiO 2 and Co N C promotes the ORR performance of Co N C catalysts. • Co N C/TiO 2 -Ti 3 C 2 shows excellent ORR performance, even better than Pt/C catalyst. Construction of multiphase nanocomposites is an effective way to develop high performance oxygen reduction catalysts. Herein, Ti 3 C 2 MXene supported Co N C and oxygen vacancy-rich TiO 2 (ov-TiO 2) composite catalyst (Co N C/TiO 2 -Ti 3 C 2) is prepared by coordination and polymerization of dopamine and Co2+ on the surface of Ti 3 C 2 nanosheets and subsequent heating treatment. The oxygen vacancies on the surface of TiO 2 nanoparticles can stabilize the Co N C catalysts as well as promote the oxygen reduction reaction (ORR) on them. Therefore, Co N C/TiO 2 -Ti 3 C 2 exhibits good ORR activity and durability, even better than the commercial Pt/C catalyst. In contrast, Ti 3 C 2 supported Co N C catalyst without ov-TiO 2 (Co N C/Ti 3 C 2) shows decreased ORR activity, indicating the significance of the synergistic effect of Co N C and ov-TiO 2. In a practical application, Co N C/TiO 2 -Ti 3 C 2 exhibits a large power density (155.3 mW cm−2) and extraordinary long-term rechargeability as the air cathode for Zn-air batteries. This strategy of in-situ growth of cocatalysts on Ti 3 C 2 MXene provides a new way for the preparation of high-performance non-noble metal catalysts. [ABSTRACT FROM AUTHOR]