Toggle Main Menu Toggle Search

Open Access padlockePrints

Visualization of the diffusion pathway of protons in (NH4)2Si0.5Ti0.5P4O13 as an electrolyte for intermediate temperature fuel cells

Lookup NU author(s): Professor Ulrich Stimming



This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society , 2018.

For re-use rights please refer to the publisher's terms and conditions.


We demonstrate that (NH4)2Si0.5Ti0.5P4O13 is an excellent proton conductor. The crystallographic information concerning the hydrogen positions is for the first time unraveled from neutron powder diffraction (NPD) data. This study shows that all the hydrogen atoms are connected though H-bonds, establishing a two-dimensional path between [(Si0.5Ti0.5)P4O132-]n layers for the proton diffusion across the crystal structure, by breaking and reconstructing intermediate H–O=P bonds. This transient species probably reduces the potential energy of the H jump from an ammonium unit to the next neighboring NH4+ unit. Both theoretical and experimental results support an interstitial proton conduction mechanism. The proton conductivities of (NH4)2Si0.5Ti0.5P4O13 reach 0.0061 and 0.024 S cm-1 in humid air at 125 oC and 250 oC, respectively. This finding demonstrates that (NH4)2Si0.5Ti0.5P4O13 is a promising electrolyte material operating at 150-250oC. This work opens up a new avenue for designing and fabricating high-performance inorganic electrolytes.

Publication metadata

Author(s): Sun C, Chen L, Shi S, Reeb B, Lopez CA, Alonso JA, Stimming U

Publication type: Article

Publication status: Published

Journal: Inorganic Chemistry

Year: 2018

Volume: 57

Issue: 2

Pages: 676-680

Print publication date: 16/01/2018

Online publication date: 02/01/2018

Acceptance date: 20/12/2017

Date deposited: 21/12/2017

ISSN (print): 0020-1669

ISSN (electronic): 1520-510X

Publisher: American Chemical Society


DOI: 10.1021/acs.inorgchem.7b02517


Altmetrics provided by Altmetric