Abstract
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.
Highlights
Improving atom economy of chemical transformations and ensuring the maximal utilization of scarce catalytic materials are central targets for sustainable chemistry[1,2,3,4,5]
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, ensuring atomic dispersion in the resulting UHD‐single‐atom catalysts (SACs)
Taking nickel SACs, which exhibit highly selective performance in the electrochemical reduction of carbon dioxide[18], as a representative example, a literature analysis shows that most of the materials reported to date are based on carbon-related materials and contain metal contents centered around 1 wt.%, with exceptional cases up to 7 wt.% (Fig. 1a)
Summary
Improving atom economy of chemical transformations and ensuring the maximal utilization of scarce catalytic materials are central targets for sustainable chemistry[1,2,3,4,5]. Taking nickel SACs, which exhibit highly selective performance in the electrochemical reduction of carbon dioxide[18], as a representative example, a literature analysis shows that most of the materials reported to date are based on carbon-related materials and contain metal contents centered around 1 wt.%, with exceptional cases up to 7 wt.% (Fig. 1a) These values are significantly lower than the expected theoretical capacity of these carriers for anchoring metal atoms. No study has achieved ultrahigh-density SACs, defined as having metal contents over 10 wt.% for carbon-based catalysts, following post‐synthetic routes, or demonstrated their enhanced productivity in catalytic applications Another scarcely addressed aspect is the extension to multimetallic systems, which is relevant for the development of technical catalysts since they often incorporate two or more metals, for example as cocatalysts, promotors or stabilizers. The bright dots in the high-magnification ADF-STEM images of
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
