Boosting ORR Activity in π-Rich Carbon-Supported Sub-3 nm Pt-Based Intermetallic Electrocatalysts via d–π Interaction

Abstract

Regulating Pt−C interactions is the key to improving the performance of carbon-supported Pt-based electrocatalysts. However, the surfaces of common commercial carbon supports are relatively inert, and achieving strong bonding with metals remains a challenge. Herein, a simple method is employed to prepare highly dispersed and sub-3 nm PtCo intermetallic compounds (IMCs) supported on π-electron-rich nitrogen-doped petroleum vacuum residue-derived porous carbon (NPPC) for the oxygen reduction reaction (ORR). Strong interaction between the d-orbitals of PtCo particles (NPs) and the π electrons of NPPC significantly optimizes the metal d-orbitals. Such strong d−π interaction and the synergistic effect of pyridinic N further enhance the activity of the catalyst for ORR. The mass activity (MA) of the prepared PtCo/NPPC-800 catalyst (1.77 A mg Pt −1) is experimentally demonstrated to be 11.8 times higher than that of commercial Pt/C (0.15 A mg Pt −1 ) at 0.9 V vs RHE. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) spectra confirm the low degree of π-electron delocalization of NPPC and highstrength Pt−C bonding. This work greatly improves the high value-added utilization of heavy oil and also provides new insights into the preparation of small-sized Pt-based IMC catalysts for ORR.