Proton conductivity spectroscopy

D.J. Jones J. Roziere (1993). Solid State Ionics, 61, 13-22. Complementarity of optical and incoherent inelastic neutron scattering spectroscopies in the study of proton conducting materials. 

The nature and mobility of ions and solvent in zeolite cages will affect the ac-impedance of the material. This effect can be utilized for zeolite-based sensor concepts where a zeolite film is coated on interdigitated electrodes. For example, it was shown that the impedance of a film of proton-conducting H-ZSM-5 is influenced by the presence of ammonia (Figs. 15, 16).[126,127] The ammonia is protonated in the zeolite, thus producing much larger ammonium ions with different mobilities in the zeolite that can be detected by impedance spectroscopy. The detection of ammonia is of interest for automotive applications where the selective catalytic reduction of NOx by ammonia is envisioned. 

Characterize the bulk hydrogen conductivity of the sintered proton-conducting ceramics using AC impedance spectroscopy and DC conductivity measurements. 

A proton conducting membrane, based on poly(vinylidene fluoride) (PVDF) grafted with polystyrene (PS) and sulfonated (PVDF-SPS), has been investigated with respect to water uptake and the state of water (Raman spectroscopy) in the material.Ostrovski and coworkers found that in the porous materials the state of water is similar to that of the bulk water, whereas, in the non-porous samples a significant part of the absorbed water differs from that of the bulk. 

The proton transfer from p-toluenesulfonic acid to the triazole rings has been established by FTIR spectroscopy. The proton conduchvity occurs via structure diffusion. The polymer is thermally stable up to around 250 °C. Cyclic voltammetry indicated an electrochemical stability domain over 3 V. The proton conductivity of the materials increases with the concentration of dopant and temperature [98],... 

Fig. 26.3. H-difTusion coefficient measured on TSA.28H2O by the PFG-NMR technique , (a) Echo attenuation as a function of applied magnetic field gradient showing separation of the contributions from the mother liquor and the solid, (b) The resultant diffusion coefficient as a function of the reciprocal temperature the diffusion coefficient calculated from the proton conductivity measured by a.c.-impedance spectroscopy is given for comparison (see Chapters 29-31).

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