Developing hybrid platinum-based electrocatalyst: leveraging multi-site synergy and tailored electrochemical microenvironment for efficient oxygen reduction reaction

Abstract

Platinum (Pt)-based single atoms and alloys represent reasonable structures to reduce the cost of electrocatalysts for the oxygen reduction reaction (ORR). However, the poor oxygen adsorption of single Pt atoms and the unfavorable surface microenvironment of alloy electrodes limit their practical applications. To address these issues, we have engineered a synergistic hybrid structure by anchoring PtNi alloys onto defective carbon (DC) modified with Pt and Ni single atoms, followed by surface modification with 2,6-diacetylpyridine (DAP) molecules. The mass activity (MA) of the optimized DAP-PtNi/Pt&Ni-SAC electrocatalyst reaches 1678.9 mA mg_Pt⁻¹, which is 10.21 times that of commercial JM Pt/C (164.5 mA mg_Pt⁻¹). Moreover, after 20,000 accelerated durability tests (ADTs), DAP-PtNi/Pt&Ni-SAC shows only a 7.9% loss in MA, demonstrating its outstanding stability. Structural characterization and theoretical calculations reveal that the interaction of Ni single atoms and PtNi alloys enhances the adsorption stability of O₂ molecules at Pt single atoms, facilitating a 4-electron ORR pathway. Meanwhile, DAP molecules adsorbed on Pt alloy sites associate with various oxygen-containing intermediates and protons through electrostatic interactions, promoting their combination. This synergistic effect between the intrinsic structure and the electrochemical microenvironment optimizes the ORR pathway in an overall manner, thus improving the kinetics of ORR.