Multiscale Architectured Nafion Membrane Derived from Lotus Leaf for Fuel Cell Applications

Abstract

Hierarchically patterned proton-exchange membranes (PEMs) have the potential to significantly increase the specific surface area, thus improving the catalyst utilization rate and performance of proton-exchange membrane fuel cells (PEMFCs). In this study, we are inspired by the unique hierarchical structure of the lotus leaf and proposed a simple three-step strategy to prepare a multiscale structured PEM. Using the multilevel structure of the natural lotus leaf as the original template, and after structural imprinting, hot-pressing, and plasma-etching steps, we successfully constructed a multiscale structured PEM with a microscale pillar-like structure and a nanoscale needle-like structure. When applied in a fuel cell, the multiscale structured PEM resulted in a 1.96-fold increase in discharge performance and a significant improvement in mass transfer compared to the membrane electrode assembly (MEA) with a flat PEM. The multiscale structured PEM has the combined advantage of a nanoscale and a microscale structure, benefiting from the markedly reduced thickness, increased surface area, and improved water management inherited from the multiscale structured lotus leaf’s superhydrophobic characteristic. Using a lotus leaf as a multilevel structure template avoids the complex and time-consuming preparation process required by commonly used multilevel structure templates. Moreover, the remarkable architecture of biological materials can inspire novel and innovative applications in many fields through nature’s wisdom.

Superhydrophobic Non-Metallic Surfaces with Multiscale Nano/Micro-Structure: Fabrication and Application

“…A multiscale rough structure surface with excellent superhydrophobicity was obtained. Some people have also used natural superhydrophobic materials, such as lotus leaves [111][112][113], rose petals [114], etc. As show in Figure 7B, using the lotus leaf as a template, Li et al [112] imprinted the micro-scale pillars of the lotus leaf onto the PDMS resin.…”

A Critical Assessment of Surface-Patterned Membranes and Their Role in Advancing Membrane Technologies

“…(I) Schematic of dominant O 2 , H 2 O, and H + pathways at the cathode. Panels G–I reprinted (adapted) with permission from ref . Copyright 2023 American Chemical Society.…”

“…Researchers have also used patterns with multiscale structures to improve the performance of the MEAs as such multiscale structures can smoothly activate the mass transport and electrochemical reactions. ,, Jang et al fabricated patterned Nafion membranes with a multiscale structure of 40.0 μm and 800 nm hole arrays with initially an EμM Nafion membrane followed by NIL as shown in Figure D . The surface-patterned membrane featuring multiscale structures achieved markedly increased power and current densities as well as lower membrane resistance in comparison to those of the conventional MEA (Figure F).…”

Straightforward Fabrication of Double Roughness Structures on a Microcrystalline Film of a Diarylethene Derivative

“…Recently, biomimetic superhydrophobic surface structures have received much attention. − The development of superhydrophobic materials mimicking these structures is rapidly increasing. − In particular, binary structures, which include micro- and nanostructures, are attracting attention because they provide the capability of superhydrophobicity in most natural life forms as well as artificial materials. − A highly representative example of double roughness structures (DRSs) having micro/nanosized roughness is the surface of a lotus leaf (Figure S1). This surface is covered with protrusions of about 10 μm in diameter and 14 μm in height. , All such protrusions are covered with wax tubes with a diameter of about 0.2 μm and a height of about 0.6 μm .…”