Du Naiying, Roy Claudie, Peach Retha, Turnbull Matthew, Thiele Simon, Bock Christina
National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario K1A 0R6, Canada.
Energy, Mining and Environment Research Centre, 1200 Montreal Road, Ottawa, Ontario K1A 0R6, Canada.
Chem Rev. 2022 Jul 13;122(13):11830-11895. doi: 10.1021/acs.chemrev.1c00854. Epub 2022 Apr 20.
This Review provides an overview of the emerging concepts of catalysts, membranes, and membrane electrode assemblies (MEAs) for water electrolyzers with anion-exchange membranes (AEMs), also known as zero-gap alkaline water electrolyzers. Much of the recent progress is due to improvements in materials chemistry, MEA designs, and optimized operation conditions. Research on anion-exchange polymers (AEPs) has focused on the cationic head/backbone/side-chain structures and key properties such as ionic conductivity and alkaline stability. Several approaches, such as cross-linking, microphase, and organic/inorganic composites, have been proposed to improve the anion-exchange performance and the chemical and mechanical stability of AEMs. Numerous AEMs now exceed values of 0.1 S/cm (at 60-80 °C), although the stability specifically at temperatures exceeding 60 °C needs further enhancement. The oxygen evolution reaction (OER) is still a limiting factor. An analysis of thin-layer OER data suggests that NiFe-type catalysts have the highest activity. There is debate on the active-site mechanism of the NiFe catalysts, and their long-term stability needs to be understood. Addition of Co to NiFe increases the conductivity of these catalysts. The same analysis for the hydrogen evolution reaction (HER) shows carbon-supported Pt to be dominating, although PtNi alloys and clusters of Ni(OH) on Pt show competitive activities. Recent advances in forming and embedding well-dispersed Ru nanoparticles on functionalized high-surface-area carbon supports show promising HER activities. However, the stability of these catalysts under actual AEMWE operating conditions needs to be proven. The field is advancing rapidly but could benefit through the adaptation of new in situ techniques, standardized evaluation protocols for AEMWE conditions, and innovative catalyst-structure designs. Nevertheless, single AEM water electrolyzer cells have been operated for several thousand hours at temperatures and current densities as high as 60 °C and 1 A/cm, respectively.
本综述概述了用于带有阴离子交换膜（AEM）的水电解槽的催化剂、膜和膜电极组件（MEA）的新兴概念，这种水电解槽也被称为零间隙碱性水电解槽。近期的许多进展得益于材料化学、MEA设计和优化操作条件的改进。对阴离子交换聚合物（AEP）的研究集中在阳离子头部/主链/侧链结构以及离子电导率和碱性稳定性等关键性能上。已经提出了几种方法，如交联、微相和有机/无机复合材料，以改善AEM的阴离子交换性能以及化学和机械稳定性。现在许多AEM的离子电导率超过了0.1 S/cm（在60 - 80°C），尽管特别是在超过60°C的温度下其稳定性还需要进一步提高。析氧反应（OER）仍然是一个限制因素。对薄层OER数据的分析表明，NiFe型催化剂具有最高的活性。关于NiFe催化剂的活性位点机制存在争议，其长期稳定性需要深入了解。向NiFe中添加Co可提高这些催化剂的电导率。对析氢反应（HER）的同样分析表明，碳载Pt占主导地位，尽管PtNi合金和Pt上的Ni(OH)团簇也表现出竞争活性。在功能化高比表面积碳载体上形成并嵌入分散良好的Ru纳米颗粒的最新进展显示出有前景的HER活性。然而，这些催化剂在实际AEMWE操作条件下的稳定性需要得到证实。该领域正在迅速发展，但通过采用新的原位技术、针对AEMWE条件的标准化评估协议以及创新的催化剂结构设计，将会受益更多。尽管如此，单个AEM水电解槽电池已经在高达60°C的温度和1 A/cm²的电流密度下运行了数千小时。
