As a green pollution-free reaction, oxygen reduction reaction (ORR) plays a significant role in many energy storage and conversion devices. Although commercial Pt/C possesses the highest ORR activity (especially in acidic medium), the high cost, low stability and poor methanol tolerance making the development of non-platinum electrocatalysts with high performance especially important. Herein, we design and synthesize a carbon nanofiber decorated by Ti₄O₇/Ti₃O₅ dual-phase nanoparticles (CNF/T4/T3) as ORR catalysts with excellent activity. With the employment of electrospinning followed by precisely controlled calcination process, the uniform fibrous morphology of the composite catalysts can be obtained. Such CNF/T4/T3 composite catalysts exhibited an improved electrochemical performance with onset and half-wave potential of 0.91 V and 0.78 V respectively in alkaline solution. By comparing the catalytic performance with the pure T4 or T3 phase decorated on the same carbon nanofiber, it is found that the mixture of the two titanium sub-oxide phases can optimize the onset potential and limited current density at the same time. Density functional theory calculations suggest that different steps of ORR take place on T3 and T4 successively, which is the main reason of the excellent ORR performance for the dual-phase structure. This work provided a novel designing concept for the functional electrocatalysts using electrospinning technique for the application of energy storage and conversion.

氧还原反应（ORR）作为一种绿色的无污染反应，在许多储能和转化装置中都发挥着重要作用。尽管市售的Pt / C具有最高的ORR活性（尤其是在酸性介质中），但其高成本，低稳定性和差的甲醇耐受性使得开发高性能的非铂电催化剂尤为重要。本文中，我们设计并合成了由Ti ₄ O ₇ / Ti ₃ O ₅装饰的碳纳米纤维。用作ORR催化剂的双相纳米颗粒（CNF / T4 / T3），具有出色的活性。通过采用电纺丝，然后进行精确控制的煅烧过程，可以获得复合催化剂的均匀纤维形态。此类CNF / T4 / T3复合催化剂在碱性溶液中表现出改善的电化学性能，其起始和半波电势分别为0.91 V和0.78V。通过将催化性能与装饰在同一碳纳米纤维上的纯T4或T3相进行比较，发现两种亚氧化钛相的混合物可以同时优化起始电势和有限的电流密度。密度泛函理论计算表明，ORR的不同步骤依次发生在T3和T4上，这是双相结构ORR性能优异的主要原因。这项工作为使用电纺丝技术的功能性电催化剂的储能和转化应用提供了新颖的设计理念。