Solution-plasma treatment for synthesizing Ketjenblack-supported Pt (1 1 1) nanocatalysts with ultra-low overpotential for Li-O2 batteries

Abstract

Reducing the loading of noble metals to achieve high catalytic activity is key to enhancing the performance and reducing the cost of lithium-oxygen (Li-O2) batteries. In this study, a highly dispersed platinum (111) catalyst supported on Ketjenblack (p-Pt/KBs) is synthesized using a novel approach that involves the interaction between solution and nonthermal plasma (SNP). The influence of different glow discharge voltages on morphology and performance of catalytic materials is investigated. The results show that the electrocatalyst prepared at 400 V has uniform Pt (111) nanocrystals embedded on Ketjenblack, achieved through plasma-induced decomposition of H2PtCl6 followed by nucleation and growth. The designed catalyst, when used as the cathode catalyst in Li-O2 batteries, demonstrates lower polarization losses with an overall overpotential of only 0.24 V compared to commercial platinum on carbon (Pt/C). The plasma effect results in significantly increased defects and grafted oxygen-containing functional groups on the support surface, providing abundant active sites conducive to anchoring of Pt nanoparticles (NPs) onto the scaffold and promoting their electronic coupling. Moreover, dominant mesopores offer ample triple-phase active zones that facilitates lithium-ion transport and rapid oxygen diffusion, further lowering energy barrier for Li2O2 decomposition and reducing the charge overpotential.