Synthesis of high-performance low-Pt (1 1 1)-loading catalysts for ORR by interaction between solution and nonthermal plasma

Abstract

One important approach to address the cost issue of fuel cells is to maximize the utilization of Pt by reducing its loading and enhancing the performance for the oxygen reduction reaction (ORR) as well as durability of catalysts. In this work, a one-step synthesis of highly dispersed low-Pt (111) electrocatalysts (p-Pt/KBs) supported by Ketjenblack is conducted using interaction between solution and nonthermal plasma (SNP). The results show that the plasma-treated platinum precursor dispersion efficiently avoids particle agglomeration and increases more defects of the support surface, which are conducive to the trapping and anchoring of platinum nanoparticles (Pt NPs). The catalyst (p-Pt/KB-NaOH) with a platinum load of 10.8 wt% is obtained by adding sodium hydroxide to the platinum precursor dispersion solution, showing better ORR performance (E1/2 = 0.88 V) and stability compared to the commercial platinum on carbon (Pt/C) catalyst (20 wt%, E1/2 = 0.86 V). This improvement is attributed to the fact that neutralizing chloroplatinic acid slows down the reduction rate of the platinum precursor, effectively controlling the rapid nucleation and slow crystal growth of platinum. As the cathode catalyst for PEMFCs, p-Pt/KB-NaOH exhibits remarkable mass-transfer performance in the high-current density domain (HCD), with maximum power density (Pmax) of 1131 mW cm−2 at 2500 mA cm−2, which is 9.1 % higher than commercial Pt/C. Moreover, the single-cell operates stably for at least 100 h at 1000 mA cm−2 with a negligible decay (1.9 %) of the working voltage, ensuring long-term durability.