Li Daohao, Li Cuiyan, Zhang Lijie, Li Hui, Zhu Liangkui, Yang Dongjiang, Fang Qianrong, Qiu Shilun, Yao Xiangdong
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
State Key Laboratory of Bio-fibers and Eco-textiles, Collaborative Innovation Center for Marine Biomass Fibers, Materials and Textiles of Shandong Province, Institute of Marine Biobased Materials, School of Environmental Science and Engineering, Qingdao University, Qingdao 266071, P. R. China.
J Am Chem Soc. 2020 May 6;142(18):8104-8108. doi: 10.1021/jacs.0c02225. Epub 2020 Apr 24.
Defective or heteroatom-doped metal-free carbon materials (MFCMs) have been regarded as efficient oxygen reduction reaction (ORR) catalysts in the past decade. However, the active centers for ORR in MFCMs are hard to confirm precisely and synthesize controllably through common methods such as high-temperature pyrolysis or heteroatom doping. To verify the precise structure acting as the active center for the ORR, we first report two crystalline metal-free thiophene-sulfur covalent organic frameworks (MFTS-COFs) as ORR catalysts. The MFTS-COFs show more positive catalytic capability than the thiophene-free COF, indicating that pentacyclic thiophene-sulfur building blocks act as active centers to induce ORR catalytic activity. MFTS-COFs with higher contents of thiophene-sulfur exhibit better ORR performance. The experimental identification is supported by density functional theory calculations. These results thus demonstrate that rational design and precise synthesis of metal-free crystalline organic materials can promote the development of new ORR catalysts.
在过去十年中，缺陷型或杂原子掺杂的无金属碳材料（MFCMs）被视为高效的氧还原反应（ORR）催化剂。然而，通过高温热解或杂原子掺杂等常规方法，难以精确确定MFCMs中ORR的活性中心并进行可控合成。为了验证作为ORR活性中心的精确结构，我们首次报道了两种结晶性无金属噻吩 - 硫共价有机框架（MFTS - COFs）作为ORR催化剂。MFTS - COFs表现出比无噻吩COF更积极的催化能力，表明五环噻吩 - 硫结构单元作为活性中心诱导ORR催化活性。具有较高噻吩 - 硫含量的MFTS - COFs表现出更好的ORR性能。密度泛函理论计算支持了这一实验鉴定。因此，这些结果表明，无金属结晶有机材料的合理设计和精确合成可以促进新型ORR催化剂的发展。
