Synergistic strain and metal-support interactions in a hollow Pt3Co/H-TiN-C nanoreactor for enhanced oxygen reduction reaction

The development of cost-effective, highly active and durable Pt-based electrocatalysts for oxygen reduction reaction (ORR) remains a major challenge to advancing proton exchange membrane fuel cells (PEMFCs). Hollow nanoarchitecture loaded with metal alloys has been widely used as a nanoreactor to regulate electronic structure of active sites and enhance reactant enrichment. In this study, PtCo alloy nanoparticles are uniformly dispersed on both outer and inner surfaces of hollow TiN spheres and carbon composite support (Pt 3 Co/H-TiN-C). The optimized Pt 3 Co/H-TiN-C nanoreactor delivers a mass activity of 64 mA mg Pt −1 and a specific activity of 0.122 mA cm Pt −2 at 0.90 V vs. RHE in 0.1 M HClO 4 solution. Furthermore, the Pt 3 Co/H-TiN-C nanoreactor enables an effective four-electron transfer pathway with high selectivity and low H 2 O 2 yield (less than 3%) toward ORR process. After accelerated durability tests, the half-wave potential of Pt 3 Co/H-TiN-C shows a decay of only 24 mV after 10,000 cycles, markedly smaller than Pt/C catalyst (74 mV). The enhanced durability and ORR kinetics of Pt 3 Co/H-TiN-C are attributed to the synergistic effect of strain effect in PtCo alloy, strong interactions between PtCo and H-TiN-C, and nanoreactor architecture. These features not only regulate the Pt electronic structure, increasing the Pt 0 content, but also expose more accessible active sites on the outer/inner surfaces to accelerate charge/mass transport. Moreover, alloyed Co atom suppress the dissolution of Pt, endowing an improved durability. This work provides a new strategy for designing efficient and durable Pt-based ORR catalysts for PEMFCs.