Graphene Oxide-Intercalated Microbial Montmorillonite to Moderate the Dependence of Nafion-Based PEMFCs in High-Humidity Environments
Ziyi Meng, Yuxi Zou, Ningning Li, Bei Wang, Xudong Fu, Rong Zhang, Shengfei Hu, Xujin Bao, Xiao Li, Feng Zhao, Qingting Liu
Abstract
The most fatal disadvantage of Nafion-based proton-exchange membrane fuel cells (PEMFCs) is their significant performance losses at low relative humidities (RH ≤ 80%), making external humidification necessary. In this work, a graphene oxide (GO)-intercalated microbial montmorillonite (mMMT) layered stack (GO@mMMT) was prepared to enhance the proton conductivity of a Nafion membrane under a low humidity at elevated temperatures. The prepared mMMT had a high specific surface area and pore volume due to microbial mineralization, allowing GO to act as a spacer intercalated between MMT layers. This layered stack greatly enhanced the water absorbance and retention capacity of GO@mMMT/Nafion composite membranes. The GO@mMMT/Nafion composite membrane exhibited excellent proton conductivity under various humidities. Particularly, the 0.5GO@mMMT/Nafion sample achieved a proton conductivity of 36.4 mS·cm –1 at 80 °C/98% RH and 17.3 mS·cm –1 at 80 °C/20% RH, which was 82% and 188% higher than that of the recast Nafion membrane, respectively. The assembled single cell reached a peak power density of 546 mW·cm –2, which was 60% higher than that of the recast Nafion single cell. These results indicate that the Nafion composite membranes with GO@mMMT incorporated layered stacks show substantial potential for PEMFC applications with simplified water management.