Ion-Exchange-Induced Selective Etching for the Synthesis of Amino-Functionalized Hollow Mesoporous Silica for Elevated-High-Temperature Fuel Cells

Jin Zhang; Jian Liu; Shanfu Lu; Haijin Zhu; David Aili; Roland De Marco; Yan Xiang; Maria Forsyth; Qingfeng Li; San Ping Jiang

doi:10.1021/acsami.7b09591

Ion-Exchange-Induced Selective Etching for the Synthesis of Amino-Functionalized Hollow Mesoporous Silica for Elevated-High-Temperature Fuel Cells

ACS Appl Mater Interfaces. 2017 Sep 20;9(37):31922-31930. doi: 10.1021/acsami.7b09591. Epub 2017 Sep 7.

Authors

Jin Zhang^{1

2}, Jian Liu², Shanfu Lu¹, Haijin Zhu³, David Aili⁴, Roland De Marco^{2

5}, Yan Xiang¹, Maria Forsyth³, Qingfeng Li⁴, San Ping Jiang^{2

5}

Affiliations

¹ Beijing Key Laboratory for Bio-inspired Energy Materials and Devices, School of Space and Environment, Beihang University , Beijing 100191, China.
² Fuels and Energy Technology Institute & Department of Chemical Engineering, Curtin University , Perth, Western Australia 6102, Australia.
³ Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia.
⁴ Department of Energy Conversion and Storage, Technical University of Denmark , Kemitorvet 207, DK-2800 Lyngby, Denmark.
⁵ Faculty of Science, Health, Education and Engineering, University of Sunshine Coast , Maroochydore DC, Queensland 4558, Australia.

PMID: 28857542
DOI: 10.1021/acsami.7b09591

Abstract

As differentiated from conventional synthetic processes, amino-functionalized hollow mesoporous silica (NH₂-HMS) has been synthesized using a new and facile strategy of ion-exchange-induced selective etching of amino-functionalized mesoporous silica (NH₂-meso-silica) by an alkaline solution. Nuclear magnetic resonance (NMR) spectroscopy and in situ time-resolved small-angle X-ray scattering (SAXS) reveal that ion-exchange-induced selective etching arises from the gradient distribution of OH^- in the NH₂-meso-silica nanospheres. Moreover, the ion-exchange-induced selective etching mechanism is verified through a successful synthesis of hollow mesoporous silica. After infiltration with phosphotungstic acid (PWA), PWA-NH₂-HMS nanoparticles are dispersed in the poly(ether sulfone)-polyvinylpyrrolidone (PES-PVP) matrix, forming a hybrid PWA-NH₂-HMS/PES-PVP nanocomposite membrane. The resultant nanocomposite membrane with an optimum loading of 10 wt % of PWA-NH₂-HMS showed an enhanced proton conductivity of 0.175 S cm^-1 and peak power density of 420 mW cm^-2 at 180 °C under anhydrous conditions. Excellent durability of the hybrid composite membrane fuel cell has been demonstrated at 200 °C. The results of this study demonstrated the potential of the facile synthetic strategy in the fabrication of NH₂-HMS with controlled mesoporous structure for application in nanocomposite membranes as a technology platform for elevated-temperature proton exchange membrane fuel cells.

Keywords: PES−PVP composite polymer; amino-functionalized hollow mesoporous silica (NH2−HMS); high-temperature proton exchange membranes (HT-PEMs); ion-exchange-induced selective etching; phosphotungstic acid (PWA); proton exchange membrane fuel cells (PEMFCs).