氧还原碳基非贵金属电催化剂研究进展

A Review of Carbon-based Non-noble Catalysts for Oxygen Reduction Reaction

质子交换膜燃料电池是一种直接将化学能转化为电能的能量转换装置,具有环境友好、能量密度高、转化效率高等优点,能够应用于便携能源及燃料电池电动车领域.但燃料电池阴极氧还原需要大量的铂基催化剂,铂价格昂贵、储量有限、易中毒的缺点限制了它的实际应用.因此,开发低成本、高活性、高稳定性的阴极非贵金属催化剂将能够显著推动质子交换膜燃料电池的大规模商业化应用.其中碳基非贵金属催化剂作为最有可能替代铂的氧还原催化剂,引起了广泛的研究.基于此,本文首先简单介绍了氧还原的机理;其次将碳基非贵金属催化剂分为过渡金属氮碳催化剂和非金属掺杂碳催化剂,对它们在材料制备和活性中心的研究进行了总结和讨论;最后,报道了碳基非贵金属催化剂在质子交换膜燃料电池单电池中的应用进展.

Proton exchange membrane fuel cells（PEMFCs） that directly convert chemical energy into electrical energy can be applied to portable power and fuel cell electric vehicles, due to their advantages such as environment-friendliness, high power density and high convert efficiency. However, the high loading of Pt-based catalysts on the cathode oxygen reduction reaction（ORR） hinder the commercial application of PEMFCs for the high price, resource shortage and easy poisoning of Pt. Thus, developing inexpensive, high performance and durability non-noble metal cathode catalysts will promote the large-scale commercialization of PEMFCs. As the most likely alternative to Pt, carbon-based non-noble ORR catalysts have been widely studied. In this review, firstly, the electrocatalytic mechanism for ORR is simply introduced. Secondly, the carbon-based non-noble ORR catalysts are divided into transition metal-nitrogen-carbon compounds（M-N-C） and non-metal heteroatom-doped carbon catalysts; the researches of material preparations and active sites are summarized and discussed. Thirdly, the applications of carbon-based non-noble ORR catalysts in PEMFC are reviewed. Although great progress has been achieved in this area of research and development, there are still some challenges for carbon-based non-noble ORR catalysts. Firstly, the ORR electrocatalytic mechanism isn＇t clear, especially carbon-based non-noble catalysts. Secondly, the ORR active sites of carbon-based non-noble catalysts remain controversial, which can be mainly divided into the transition metal coordination compounds, the doped heteroatom, the filled metal and the defect sites. Thirdly, the actual activity and stability of carbon-based non-noble catalysts are still below the PEMFC target. In summary, the future research directions on carbon-based non-noble catalysts for PEMFC applications would be proposed as follows：（1） fundamentally understanding the ORR mechanisms and their relationship with catalyst active site structures and composition using both theoretical calculations and experimental approaches;（2） improving catalyst activity and stability to satisfy the practical application of PEMFC.