基于非贵金属氧还原催化剂的质子交换膜燃料电池性能

质子交换膜燃料电池的成本和寿命问题是制约其商业化的主要瓶颈. 开发高效稳定的新型非铂氧还原催化剂是降低电池成本的重要途径. 过渡金属-氮-碳型非贵金属催化剂具有较高催化活性、资源丰富、价格低廉等优点, 被认为是未来最有希望替代铂的氧还原催化剂. 本综述从催化剂的设计构筑、催化层结构优化以及电池测试等方面, 对过渡金属-氮-碳型非贵金属催化剂的国内外最新研究进展进行了重点讨论, 并对未来其发展趋势提出展望.

Fuel Cell Performance of Non-Precious Metal Based Electrocatalysts

The commercialization of proton exchange membrane fuel cells (PEMFCs) is hindered by high cost and low durability of Pt based electrocatalysts. Developing efficient and durable non-precious metal catalysts is a promising approach to addressing these conundrums. Among them, transition metals dispersed in a nitrogen (N)-doped carbon support (M-N-C) show good oxygen reduction reaction activity. This article reviews recent progress in M-N-C catalysts development, focusing on the catalysts design, membrane electrode assembly fabrication, fuel cell performance, and durability testing. Template-assisted approach is an efficient way to synthesize M-N-C materials with homogeneously dispersed single atom active site and reduced metal particles, carbides formation. However, the issue related to low intensity of active sites should be addressed via strengthening metal-ligand interaction and using high surface area precursors. In general, the catalyst loading for the membrane electrode assembly (MEA) of non-precious catalyst is high (3 ~ 4 mg·cm^-2) in order to obtain acceptable performance, which is also highly dependent on ink preparation and coating protocol, ionomer/catalyst ratio, etc. The highest power densities for Fe-N-C and Co-N-C are reported to be 1.18 and 0.87 W·cm^-2 with O₂ at the cathode, respectively. Despite the significant progress in non-precious metal catalysts development, the undesired durability (only a few hundreds of hours) is still far from the target of 5000 h by 2025. Thus, much more efforts should be spent on improving their durability.