Yang Limeng, Shao Zhigang
School of Textile Science and Engineering, Xi'an Polytechnic University 19 Jinhua Road Xi'an 710048 China
Dalian National Laboratories for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China.
RSC Adv. 2019 Dec 19;9(72):42236-42244. doi: 10.1039/c9ra08867a. eCollection 2019 Dec 18.
The development of low-cost, efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) is desirable but remains a great challenge. We report a convenient and efficient synthesis approach of highly dispersed Fe-N catalysts for ORR. Typically, Fe-Zn-ZIF (zeolitic imidazolate frameworks) nanocrystals cast as precursor and graphene as supports, highly dispersed Fe-N species were fabricated with PVP (polyvinyl pyrrolidone) as surfactant pyrolysis. With the help of graphene and surfactant, the agglomeration of iron particles has been avoided during pyrolysis, and the size and morphology of ZIF particles intercalating into the graphene layers can be regulated precisely as well. The amount of Fe-N active sites in C-rGO-ZIF catalyst arrived 4.29%, which is obviously higher than most monodispersed non-precious metal catalysts reported. The obtained C-rGO-ZIF catalyst exhibits a high onset potential of 0.89 V and a half-wave potential of 0.77 V, which is only 30 mV away from Pt/C in acidic media. The active sites of the catalyst was characterized and found to be the highly dispersed Fe-N species, large and accessible specific surface area of graphene and abundant active nitrogen atoms. When the C-rGO-ZIF catalyst was applied in the cathode of fuel cell, the power density can reach up to 301 mW cm, which highlights a practical application potential on small power supplies.
开发用于氧还原反应（ORR）的低成本、高效且稳定的电催化剂是人们所期望的，但仍然是一个巨大的挑战。我们报道了一种便捷高效的合成方法，用于制备用于ORR的高度分散的Fe-N催化剂。通常，以Fe-Zn-ZIF（沸石咪唑酯骨架）纳米晶体为前驱体，石墨烯为载体，以聚乙烯吡咯烷酮（PVP）为表面活性剂进行热解，制备出高度分散的Fe-N物种。借助石墨烯和表面活性剂，在热解过程中避免了铁颗粒的团聚，并且精确调控了嵌入石墨烯层中的ZIF颗粒的尺寸和形态。C-rGO-ZIF催化剂中Fe-N活性位点的含量达到4.29%，明显高于大多数已报道的单分散非贵金属催化剂。所制备的C-rGO-ZIF催化剂在酸性介质中表现出0.89 V的高起始电位和0.77 V的半波电位，与Pt/C相比仅相差30 mV。对催化剂的活性位点进行表征，发现其为高度分散的Fe-N物种、石墨烯大且可及的比表面积以及丰富的活性氮原子。当将C-rGO-ZIF催化剂应用于燃料电池阴极时，功率密度可达301 mW/cm²，这突出了其在小功率电源方面的实际应用潜力。
