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Abstract: This paper focuses on the differences between the thermal behaviour of cation exchanged membrane based on Short Side Chain (SSC) and Long Side Chain (LSC) polymers. The α relaxation of alkali and Cu2+ exchanged membranes showed dependency on ion exchange capacity and the length of the side chain similar to that of H+-form membranes. The modulus drop of multivalent contaminated membranes was attributed to a degradation process except for Ba2+and Zn2+ LSC exchanged membrane. The thermal behaviour as function of the Lewis Acid Strength, LAS, of the cation could originate from infrared (IR) vibrational changes. For cations with LAS<0.3, the 1060cm−1 and 970cm−1 mode induce concurrent shift towards high wavenumbers. This suggests a stiffening of the corresponding bonds resulting in the improvement of the membrane''s thermal stability. The cations with LAS>0.3 decrease the 970cm−1 wavenumber which could explain the enhancement of the degradation. [Copyright &y& Elsevier]

An Ir 0.7 Ru 0.3 Ox nanosized anode electrocatalyst was coupled to an Aquivion short-side chain perfluoro-sulfonic acid membrane (120 μm; EW: 870 g/eq) for operation in a PEM electrolyser. A conventional carbon supported Pt catalyst was used as cathode. An excellent performance, of 4 A cm −2 at 1.9 V at 90 °C, was achieved for this electrolyser configuration in the presence of a moderate noble metal loading (1.5 mg cm −2 Ir + Ru; 0.5 mg cm −2 Pt). The interface of IrRuOx with Aquivion provided a 10% enhancement in performance compared to an equivalent interface with a Nafion membrane of similar thickness but characterized by a larger equivalent weight (EW: 1100 g/eq). The enhanced performance essentially derived from a decrease of polarization resistance. This appeared to be due to better interface characteristics between the electrodes and Aquivion ® ionomer giving rise to an increased catalyst utilization. Whereas, no significant change in Tafel slope and activation energy was recorded indicating a similar reaction mechanism. [ABSTRACT FROM AUTHOR]

An Aquivion® E87-12S short-side-chain perfluorosulfonic acid (SSC-PFSA) membrane with equivalent weight (EW) of 870g/eq and 120μm thickness produced by Solvay Specialty Polymers was tested in a polymer electrolyte membrane water electrolyzer (PEMWE). For comparison, a benchmark Nafion® N115 membrane (EW 1100g/eq) of similar thickness was investigated under similar operating conditions. Both membranes were tested in conjunction with in-house prepared unsupported IrO2 anode and carbon-supported Pt cathode electrocatalysts. The electrocatalysts consisted of nanosized IrO2 and Pt particles (particle size ~2–4nm). Electrochemical tests showed better water splitting performance for the Aquivion® membrane and ionomer based membrane-electrode assembly (MEA) as compared to Nafion®. Lower ohmic drop constraints and smaller polarization resistance were observed for the electrocatalyst–Aquivion® ionomer interface indicating a better catalyst–electrolyte interface. A current density of 3.2Acm−2 for water electrolysis was recorded at 1.8V cell voltage and 90°C with the Aquivion® based MEA. Some performance decay with time was observed indicating that the system requires further optimization of the interface characteristics. [ABSTRACT FROM AUTHOR]