Chen Jiale, Wang Li, Wang Lei
Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
Guangdong Research Center for Interfacial Engineering of Functional Materials, Shenzhen University, Shenzhen 518060, China.
ACS Appl Mater Interfaces. 2020 Sep 16;12(37):41350-41358. doi: 10.1021/acsami.0c10527. Epub 2020 Sep 1.
Phosphoric acid (PA)-doped polybenzimidazoles generally require high PA doping levels to achieve high conductivity as high-temperature proton exchange membranes. However, high PA doping levels result in a significant decrease in the mechanical properties of and PA leaching from the membranes. Herein, a Zr-based metal-organic framework material (UIO-66) was introduced into poly[2,2'-(-oxydiphenylene)-5,5'-benzimidazole] (OPBI) membranes. The composite membranes exhibited long-range continuous proton transport channels when the mass ratio of UIO-66 to OPBI was ≥30 wt %. The long-range continuous proton transport channels endowed the composite membranes with high proton conductivity at low PA doping levels. When the doping of UIO-66 in the OPBI membrane reached 40 wt %, the membrane exhibited the highest proton conductivity (0.092 S cm, at 160 °C) at a low PA uptake (73.25%), while the conductivity of the pristine OPBI membrane was 0.050 S cm with a high PA uptake (217.43%). Additionally, in the oxyhydrogen fuel cell test, 40%UIO-66@OPBI membranes exhibited excellent fuel cell performance with a peak power density of 583 mW cm at 160 °C, which is 50% higher than that of the pristine OPBI membrane (374 mW cm). A single cell based on 40%UIO-66@OPBI also demonstrated good durability and could remain at about 600 mV after 500 h of operation under a constant load of 200 mA cm.
作为高温质子交换膜，磷酸（PA）掺杂的聚苯并咪唑通常需要高PA掺杂水平才能实现高导电性。然而，高PA掺杂水平会导致膜的机械性能显著下降以及PA从膜中浸出。在此，将一种锆基金属有机框架材料（UIO-66）引入聚[2,2'-（-氧化二亚苯基）-5,5'-苯并咪唑]（OPBI）膜中。当UIO-66与OPBI的质量比≥30 wt%时，复合膜表现出长程连续的质子传输通道。这些长程连续的质子传输通道使复合膜在低PA掺杂水平下具有高质子传导率。当OPBI膜中UIO-66的掺杂量达到40 wt%时，该膜在低PA吸收量（73.25%）下表现出最高的质子传导率（160℃时为0.092 S/cm），而原始OPBI膜在高PA吸收量（217.43%）下的传导率为0.050 S/cm。此外，在氢氧燃料电池测试中，40%UIO-66@OPBI膜表现出优异的燃料电池性能，在160℃时峰值功率密度为583 mW/cm²，比原始OPBI膜（374 mW/cm²）高50%。基于40%UIO-66@OPBI的单电池也表现出良好的耐久性，在200 mA/cm²的恒定负载下运行500小时后可保持在约600 mV。
