Stable boron nitride nanocomposites based membranes for high-efficiency proton conduction

Abstract

Proton conduction is a not only a universal and fundamental process in nature but also have been widely used in energy- and environment-related applications. Achieving high-efficiency proton conduction is very important in these areas. Herein, stable and selective membranes with novel ionic nanochannels based on functionalized two-dimensional boron nitride nanocomposites (NBN) are successfully fabricated. The proton conductivity of Nafion-sNBNM at 80 °C - 95 %RH is as high as 0.44 S cm−1. At the same time, NBN-sNBNM shows impressing stability at high-humidity conditions and in redox environments. The high proton conductivity could be attributed to the favorable microphysical and microchemical environments of the nanochannels in the membranes. On one side, the double-layer space among the closely assembled NBN propels the local surface-charge enhanced proton conduction. On the other side, the formation of connected long-range ionic nanochannels and quasi-isotropic architecture facilitate the long-range proton conduction. Benefiting from the excellent stability of NBN, the proton conductivity of Nafion-sNBNM at high-temperature and low-humidity conditions could be conveniently increased by H3PO4 adsorption. Furthermore, Nafion-sNBNM also shows low methanol permeability and high membrane selectivity. These outstanding properties of Nafion-sNBNM demonstrate great application potential in many areas.