Confined Ultrafine Pt in Porous Carbon Fibers and Their N-Enhanced Heavy d-π Effect

The heavy d-π effect is an important theoretical model for strong Pt–C interaction, and its enhancement is critical to the high-performance design of Pt/C electrocatalysts. Common chemical N-doping to the carbon support can provide possibilities for enhanced electrocatalysis but most often leads to random interaction with Pt nanoparticles (Pt-NPs) and uncontrollable tuning of the heavy d-π effect. Directional confinement of Pt-NPs within N-doped carbon to directly enhance the heavy d-π effect is therefore mostly preferred but rarely reported. Herein, confined ultrafine Pt-NPs in N-doped porous carbon fibers (Pt@NDPCF) were obtained by a combination method involving electrospinning, carbonization, and directional replacement. Such a synthetic strategy leads to highly dispersed, ultrafine Pt-NPs in hierarchically porous carbon fibers and a strong directional interaction of Pt with pyridinic N, which significantly enhances the heavy d-π effect, greatly facilitating electron transfer and optimizing Pt 5d orbitals. Based on these advances, Pt@NDPCF exhibited outstanding activity and superior durability in the hydrogen evolution reaction (HER), with 24 mV lower overpotential at 10 mA cm–2 and a much smaller activity loss after 10,000 cycles of durability tests in comparison with a commercial Pt/C catalyst. This work sheds new lights on the design of high-performance Pt-based nanomaterials toward HER or other practical applications.