Journal of Membrane Science 356 (2010) 147–153 Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Nanoporous niobium phosphate electrolyte membrane for low temperature fuel cell Zhanli Chai a,b,c , Dehua Dong b , Cheng Wang a,∗ , Hongjie Zhang a , Paul A. Webley b , Dongyuan Zhao b , Huanting Wang b,∗∗ a State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China b Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia c Graduate School of the Chinese Academy of Sciences, Beijing, PR China article info Article history: Received 6 October 2009 Received in revised form 21 March 2010 Accepted 1 April 2010 Available online 9 April 2010 Keywords: Niobium phosphate Nanoporous membrane Proton exchange membrane fuel cell Poly(furyfuryl alcohol) abstract Nanoporous niobium phosphate (Nb–P) electrolyte membranes were prepared by dry pressing Nb–P nanoparticles for low temperature fuel cells. Highly dispersible Nb–P nanoparticles were synthesized by dispersing Nb–P precursor in furfuryl alcohol, which was polymerized to poly(furyfuryl alcohol) as a space-confinement additive during calcination. SEM, TEM and a range of spectroscopies were used to characterize Nb–P particles and membranes (discs). Nanoporous Nb–P membrane exhibited high proton conductivity (17.4 mS cm -1 ), low methanol permeability (1.1 × 10 -7 cm 2 s -1 ) whereas Nb–P membrane prepared from Nb–P particles synthesized without adding furfuryl alcohol had poor proton conduc- tivity (0.341 mS cm -1 ) and high methanol permeability (3.13 × 10 -5 cm 2 s -1 ). The cell prepared with nanoporous Nb–P membrane showed good cell performance when operated as both H 2 –O 2 fuel cell at room temperature and as DMFC at 60 ◦ C; also this cell performs better than the cell with Nafion mem- brane at a current density of <72 mA cm -2 , and its peak power density is comparable to the cell with Nafion membrane. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Inorganic proton conductive membranes are an important class of solid electrolytes for fuel cells. A wide variety of inor- ganic proton conductive membranes have been reported so far. For instance, oxide ceramics such as Nd 2 O 3 doped BaCeO 3 [1], La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-x [2], rare-earth ortho-niobates and ortho-tantalates [3], or phosphate [4] show appreciable proton con- ductivities in the range of 10 -4 to 10 -3 S cm -1 at temperatures higher than 600 ◦ C. Solid acids such as CsHSO 4 [5], CsHPO 4 [6], In 3+ doped SnP 2 O 7 [7], TiO 2 –P 2 O 5 [8] and Y-doped zirconium pyrophos- phate [9] possess good proton conductivities (∼10 -2 S cm -1 ) under water-free condition at 150–350 ◦ C. To overcome the difficulties in the preparation of a thin membrane using a solid acid, and reduce the dissolution of the solid acid in the water produced at the cathode, CsH 2 PO 4 was embedded into the nanoporous channels of anodic alumina membranes. The resultant proton con- ducting membrane exhibited a good cell performance at room ∗ Corresponding author. Tel.: +86 431 8526 2770; fax: +86 431 8569 8041. ∗∗ Corresponding author. Tel.: +61 3 9905 3449; fax: +61 3 9905 5686. E-mail addresses: cwang@ciac.jl.cn (C. Wang), huanting.wang@eng.monash.edu.au (H. Wang). temperature [10]. Many amorphous phosphates such as zirco- nium phosphate [11] and calcium phosphate hydrogels [12] show high proton conductivity (∼10 -2 S cm -1 ) at low temperatures (e.g., room temperature). By forming a nanoporous structure or acid- functionalization, some inorganic materials such as mesoporous titania [13–15] and functionalized mesostructured silica composite (meso-SiO 2 –C 12 EO 10 OH–CF 3 SO 3 H) [16], exhibit proton conduc- tivities of 10 -3 to 10 -2 S cm -1 at room temperature when fully hydrated. Because of their high proton conductivity at low temper- ature and hygroscopicity, these amorphous or nanoporous proton conducting materials have been widely incorporated into polymers to fabricate nanocomposite membranes for proton exchange mem- brane (PEM) fuel cells. For example, inorganic proton conductor modified Nafion membranes exhibit higher proton conductivity at elevated temperatures and lower alcohol fuel permeability than plain Nafion membrane [17,18]. It is noted that the proton conductivity of solid acid elec- trolytes can be enhanced by increasing their surface area. This is because high surface area and more interconnected porous chan- nels lead to more localized proton-rich domains that facilitate proton conduction [19]. In the present work, we attempt to fabri- cate nanostructured niobium phosphate (Nb–P) membranes from Nb–P nanoparticles for low temperature PEM fuel cells. The Nb–P nanoparticles are synthesized by dispersing Nb–P precursor in fur- 0376-7388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2010.04.001