作者：Juan Wu, Shijun Nie, Hai Liu, Chunli Gong,* Quanyuan Zhang,* Zushun Xu, Guangfu Liao*
关键字：direct methanol fuel cells
论文来源：期刊
具体来源：https://doi.org/10.1039/D2TA03166C
发表时间：2022年
The development of low-cost and high-performance proton exchange membranes (PEMs) for direct methanol fuel cell (DMFC) applications is a promising solution to the energy shortage. In this work, a series of sulfonated poly(ether ether ketone)s (SPEEKs) modified with two nucleobases, adenine (A) and cytosine (C) with different degrees of substitution, SPEEK-Ax and SPEEK-Cx were successfully synthesized. The basic sites of A and C can immobilize phosphoric acid (PA) molecules through acid–base interaction to fabricate PA-doped SPEEK membranes. In addition, the formation of ionic crosslinking caused by basic sites enhances the thermal stability and mechanical strength of the PA-doped membranes. As a result, the SPEEK-Ax/PA and SPEEK-Cx/PA membranes possess satisfactory strength (>23.5 MPa) even if their elongation at break remained at a very high level (>200%) in the hydrated state. These PA-doped membranes exhibited ultra-high proton conductivities (all beyond 220 mS cm?1) at 80 °C, while the conductivity of SPEEK was only 43.8 mS cm?1 with similar IEC values. This may be attributed to the acid–base pairs between the acidic sites (–SO3H and H2PO4?) and basic sites, which can serve as efficient transportation paths for proton migration. Furthermore, the ionic crosslinked structure decreased the methanol crossover of the membranes. The SPEEK-C50/PA membrane possesses outstanding DMFC performance with a maximum power density of 141.7 mW cm?2 when fed with 2 M methanol at 80 °C, more than twice as much as that of SPEEK (67.2 mW cm?2) and Nafion 115 (64.1 mW cm?2), which outperforms the majority of previously reported Nafion and SPEEK membranes. Therefore, the prepared nucleobase modified PEMs showed promising potential for high-performance DMFC application.