Scalable and Controllable Synthesis of Pt-Ni Bunched-Nanocages Aerogels as Efficient Electrocatalysts for Oxygen Reduction Reaction

摘要

Developing efficient and stable Pt-based oxygen reduction reaction (ORR)electrocatalysts via both economical and controllable routes is critical for thepractical application of electrochemical energy devices. Herein, a scalable, controllable,and general ambient-O_2-involved aqueous-solution cultivating strategyto prepare Pt_xM_y (M = Ni, Fe, Co) bunched-nanocages aerogels (BNCs AG) isdemonstrated, based on a newly established high-M-to-Pt-precursor-ratio-and-B-incorporation-facilitated M-rich core and Pt-rich shell hydrogel formation process.The Pt_(83)Ni_(17) BNCs AG shows prominent ORR performance with a massactivity (MA) of 1.95 A mg_(Pt)~(?1) and specific activity of 3.55 mA cm~(?2), which are8.9-times and 9.6-times that of Pt supported on carbon (Pt/C), respectively. Particularly,the Pt_(83)Ni_(17) BNCs AG displays greatly enhanced durability (MA 82.6retention) compared to Pt/C (MA 31.8 retention) after a 20 000-cycles accelerateddurability test. Systematic studies including density functional theory calculationsuncover that the excellent activity is closely related to the optimizedligand and strain effects with the optimized Ni content in this aerogel; theoutstanding durability is endowed by the lowered-down Ni leaching with theoptimized Pt/Ni ratio and the inhibited sintering due to its appropriate porosity.This work provides new perspectives on the development of electrocatalystswith both high performance and low cost.