Wang Yi, Li Chongao, Han Xiao, Bai Jintao, Wang Xuejing, Zheng Lirong, Hong Chunxia, Li Zhijun, Bai Jinbo, Leng Kunyue, Lin Yue, Qu Yunteng
International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University, Xi'an, Shaanxi, 710069, China.
Department of Chemistry, Department of Applied Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China.
Nat Commun. 2024 Jul 6;15(1):5675. doi: 10.1038/s41467-024-50061-1.
Catalyst systems populated by high-density single atoms are crucial for improving catalytic activity and selectivity, which can potentially maximize the industrial prospects of heterogeneous single-atom catalysts (SACs). However, achieving high-loading SACs with metal contents above 10 wt% remains challenging. Here we describe a general negative pressure annealing strategy to fabricate ultrahigh-loading SACs with metal contents up to 27.3-44.8 wt% for 13 different metals on a typical carbon nitride matrix. Furthermore, our approach enables the synthesis of high-entropy single-atom catalysts (HESACs) that exhibit the coexistence of multiple metal single atoms with high metal contents. In-situ aberration-corrected HAADF-STEM (AC-STEM) combined with ex-situ X-ray absorption fine structure (XAFS) demonstrate that the negative pressure annealing treatment accelerates the removal of anionic ligand in metal precursors and boosts the bonding of metal species with N defective sites, enabling the formation of dense N-coordinated metal sites. Increasing metal loading on a platinum (Pt) SAC to 41.8 wt% significantly enhances the activity of propane oxidation towards liquid products, including acetone, methanol, and acetic acid et al. This work presents a straightforward and universal approach for achieving many low-cost and high-density SACs for efficient catalytic transformations.
由高密度单原子组成的催化剂体系对于提高催化活性和选择性至关重要，这有可能使多相单原子催化剂（SACs）的工业前景最大化。然而，实现金属含量高于10 wt%的高负载SACs仍然具有挑战性。在此，我们描述了一种通用的负压退火策略，用于在典型的氮化碳基质上制备金属含量高达27.3-44.8 wt%的13种不同金属的超高负载SACs。此外，我们的方法能够合成高熵单原子催化剂（HESACs），其表现出多种高金属含量的金属单原子共存。原位像差校正高角度环形暗场扫描透射电子显微镜（AC-STEM）与非原位X射线吸收精细结构（XAFS）相结合表明，负压退火处理加速了金属前驱体中阴离子配体的去除，并促进了金属物种与N缺陷位点的结合，从而形成密集的N配位金属位点。将铂（Pt）SAC上的金属负载量增加到41.8 wt%，显著提高了丙烷氧化生成包括丙酮、甲醇和乙酸等液体产物的活性。这项工作提出了一种直接且通用的方法，用于制备许多低成本、高密度的SACs以实现高效催化转化。
