Choi Won Ho, Kim Keon-Han, Lee Heebin, Choi Jae Won, Park Dong Gyu, Kim Gi Hwan, Choi Kyung Min, Kang Jeung Ku
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea.
Department of Chemical and Biological Engineering, Sookmyung Women's University, Cheongpa-ro 47-gil 100, Yongsan-gu, Seoul, 04310, Republic of Korea.
Adv Sci (Weinh). 2021 Jun;8(11):e2100044. doi: 10.1002/advs.202100044. Epub 2021 Mar 24.
Multimetallic electrocatalysts have shown great potential to improve electrocatalytic performance, but their deteriorations in activity and durability are yet to be overcome. Here, metal-organic fragments with adhesive excipient to realize high activity with good durability in oxygen evolution reaction (OER) are developed. First, a leaf-like zeolitic-imidazolate framework (ZIF-L) is synthesized. Then, ionized species in hydrogen plasma attack preferentially the organic linkers of ZIF-L to derive cobalt-imidazole fragments (CIFs) as adhesive excipient, while they are designed to retain the coordinated cobalt nodes. Moreover, the vacant coordination sites at cobalt nodes and the unbound nitrogen at organic linkers induce high porosity and conductivity. The CIFs serve to stably impregnate trimetallic FeNiMo electrocatalysts (CIF:FeNiMo), and CIF:FeNiMo containing Fe contents of 22% and hexavalent Mo contents show to enable high activity with low overpotentials (203 mV at 10 mA cm and 238 mV at 100 mA cm ) in OER. The near O K-edge extended X-ray absorption fine structure proves further that high activity for OER originates from the partially filled e orbitals. Additionally, CIF:FeNiMo exhibit good durability, as demonstrated by high activity retention during at least 45 days in OER.
多金属电催化剂在提高电催化性能方面已显示出巨大潜力，但其活性和耐久性的下降仍有待克服。在此，开发了具有粘性赋形剂的金属有机片段，以在析氧反应（OER）中实现高活性和良好的耐久性。首先，合成了叶状沸石咪唑骨架（ZIF-L）。然后，氢等离子体中的离子化物种优先攻击ZIF-L的有机连接体，衍生出钴咪唑片段（CIFs）作为粘性赋形剂，同时设计使其保留配位钴节点。此外，钴节点处的空配位位点和有机连接体上未结合的氮导致高孔隙率和导电性。CIFs用于稳定浸渍三金属FeNiMo电催化剂（CIF:FeNiMo），含22%铁含量和六价钼含量的CIF:FeNiMo在OER中显示出在低过电位下具有高活性（在10 mA cm时为203 mV，在100 mA cm时为238 mV）。近O K边扩展X射线吸收精细结构进一步证明，OER的高活性源于部分填充的e轨道。此外，CIF:FeNiMo表现出良好的耐久性，在OER中至少45天的高活性保留证明了这一点。
