Hai Xiao, Xi Shibo, Mitchell Sharon, Harrath Karim, Xu Haomin, Akl Dario Faust, Kong Debin, Li Jing, Li Zejun, Sun Tao, Yang Huimin, Cui Yige, Su Chenliang, Zhao Xiaoxu, Li Jun, Pérez-Ramírez Javier, Lu Jiong
Department of Chemistry, National University of Singapore, Singapore, Singapore.
Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research, Singapore, Singapore.
Nat Nanotechnol. 2022 Feb;17(2):174-181. doi: 10.1038/s41565-021-01022-y. Epub 2021 Nov 25.
The stabilization of transition metals as isolated centres with high areal density on suitably tailored carriers is crucial for maximizing the industrial potential of single-atom heterogeneous catalysts. However, achieving single-atom dispersions at metal contents above 2 wt% remains challenging. Here we introduce a versatile approach combining impregnation and two-step annealing to synthesize ultra-high-density single-atom catalysts with metal contents up to 23 wt% for 15 metals on chemically distinct carriers. Translation to a standardized, automated protocol demonstrates the robustness of our method and provides a path to explore virtually unlimited libraries of mono- or multimetallic catalysts. At the molecular level, characterization of the synthesis mechanism through experiments and simulations shows that controlling the bonding of metal precursors with the carrier via stepwise ligand removal prevents their thermally induced aggregation into nanoparticles. The drastically enhanced reactivity with increasing metal content exemplifies the need to optimize the surface metal density for a given application. Moreover, the loading-dependent site-specific activity observed in three distinct catalytic systems reflects the well-known complexity in heterogeneous catalyst design, which now can be tackled with a library of single-atom catalysts with widely tunable metal loadings.
将过渡金属稳定为在适当定制的载体上具有高面密度的孤立中心，对于最大化单原子多相催化剂的工业潜力至关重要。然而，在金属含量高于2 wt%时实现单原子分散仍然具有挑战性。在此，我们引入一种将浸渍和两步退火相结合的通用方法，以在化学性质不同的载体上合成金属含量高达23 wt%的15种金属的超高密度单原子催化剂。转化为标准化的自动化方案证明了我们方法的稳健性，并为探索几乎无限的单金属或多金属催化剂库提供了一条途径。在分子水平上，通过实验和模拟对合成机理的表征表明，通过逐步去除配体来控制金属前驱体与载体的键合可防止其热诱导聚集成纳米颗粒。随着金属含量增加，反应活性大幅增强，这例证了针对特定应用优化表面金属密度的必要性。此外，在三个不同催化体系中观察到的与负载相关的位点特异性活性反映了多相催化剂设计中众所周知的复杂性，现在可以通过具有广泛可调金属负载量的单原子催化剂库来解决这一问题。
