Han Xu, Zhang Tianyu, Wang Xinhe, Zhang Zedong, Li Yaping, Qin Yongji, Wang Bingqing, Han Aijuan, Liu Junfeng
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
Nat Commun. 2022 May 24;13(1):2900. doi: 10.1038/s41467-022-30520-3.
Single-atom catalysts (SACs) show great promise in various applications due to their maximal atom utilization efficiency. However, the controlled synthesis of SACs with appropriate porous structures remains a challenge that must be overcome to address the diffusion issues in catalysis. Resolving these diffusion issues has become increasingly important because the intrinsic activity of the catalysts is dramatically improved by spatially isolated single-atom sites. Herein, we develop a facile topo-conversion strategy for fabricating hollow mesoporous metal-nitrogen-carbon SACs with enhanced diffusion for catalysis. Several hollow mesoporous metal-nitrogen-carbon SACs, including Co, Ni, Mn and Cu, are successfully fabricated by this strategy. Taking hollow mesoporous cobalt-nitrogen-carbon SACs as a proof-of-concept, diffusion and kinetic experiments demonstrate the enhanced diffusion of hollow mesoporous structures compared to the solid ones, which alleviates the bottleneck of poor mass transport in catalysis, especially involving larger molecules. Impressively, the combination of superior intrinsic activity from Co-N sites and the enhanced diffusion from the hollow mesoporous nanoarchitecture significantly improves the catalytic performance of the oxidative coupling of aniline and its derivatives.
单原子催化剂（SACs）由于其最大的原子利用效率，在各种应用中显示出巨大的潜力。然而，可控合成具有适当多孔结构的SACs仍然是一个必须克服的挑战，以解决催化过程中的扩散问题。解决这些扩散问题变得越来越重要，因为通过空间隔离的单原子位点，催化剂的本征活性得到了显著提高。在此，我们开发了一种简便的拓扑转换策略，用于制备具有增强扩散性能的中空介孔金属-氮-碳SACs用于催化。通过该策略成功制备了几种中空介孔金属-氮-碳SACs，包括钴、镍、锰和铜。以中空介孔钴-氮-碳SACs为例，扩散和动力学实验表明，与实心结构相比，中空介孔结构的扩散性能增强，这缓解了催化过程中传质不良的瓶颈，特别是涉及较大分子的情况。令人印象深刻的是，钴-氮位点的优异本征活性与中空介孔纳米结构增强的扩散性能相结合，显著提高了苯胺及其衍生物氧化偶联的催化性能。
