Interfacial Engineering of Bimetallic Carbide and Cobalt Encapsulated in Nitrogen-Doped Carbon Nanotubes for Electrocatalytic Oxygen Reduction.

Heterojunction engineering is a fundamental strategy to develop efficient electrocatalysts for the oxygen reduction reaction by tuning electronic properties through interfacial cooperation. In this study, a heterojunction electrocatalyst consisting of bimetallic carbide Co3 ZnC and cobalt encapsulated within N-doped carbon nanotubes (Co3 ZnC/Co@NCNTs) is synthesized by a facile two-step ion exchange-thermolysis pathway. Co3 ZnC/Co@NCNTs effectively promotes interfacial charge transport between the different components with optimizes adsorption and desorption of intermediate products at the heterointerface. In situ-grown N-doped carbon nanotubes (NCNTs) not only improve the electrical conductivity but also suppress the oxidation of transition metal nanoparticles in alkaline media. Moreover, the abundant nitrogen types (pyridinic N, Co-Nx , and graphitic nitrogen) in the carbon skeleton provide more active sites for oxygen adsorption. Benefitting from this optimized structure, Co3 ZnC/Co@NCNTs hybrid not only demonstrates excellent oxygen reduction activity, with a half-wave potential of 0.83 V and fast mass transport with limited current density of 6.23 mA cm-2 , but also exhibits superior stability and methanol tolerance, which surpass those of commercial Pt/C catalysts. This work provides an effective heterostructure for interfacial electronic modulation to improve electrocatalytic performance.