Single-atom is not alone
Single-atom catalysts are not exactly what their name suggests: catalysts comprised of one single atom. There is an affinity between the single metal atom and the support which makes them an integral whole: Just like the marriage.
The link for paper in Nature Communications is here:
When the metal active center is dispersed to the single-atom scale, thanks to the boosted surface free energy, unsaturated coordination environment and the interaction of the metal-support will give the single-atom catalyst novel properties. The atomically dispersed active center not only significantly improves the utilization efficiency of metal atoms, but also changes the energy and selectivity of the adsorption and desorption of reaction molecules on the catalytic center. In traditional single-atom catalysts, it is difficult to avoid the re-aggregation of metal atoms. What's more important, the ambiguous relationship of the interaction between metal atom and support remarkably limited the improvement of catalytic performance.
Here, for the first time, we reported a new strategy (assembly / leaching) for the preparation of single-atom catalyst. By applying the strong chemical interaction between two counterpart 2D materials, cobalt nanodisks were successfully assembled onto the surface of molybdenum disulfide nanosheets, following by the leaching process with acid to obtain the high loading metal cobalt single atom array on distorted metal phase molybdenum disulfide (SA Co-D 1T MoS2).
SA Co-D 1T MoS2 exhibits outstanding hydrogen evolution reaction activity (as good as commercial Pt) and excellent long-term stability. The active site block experiment reveals that the single atom Co is the principal catalytic center, although both single Co atom and 2H to D-1T phase transformation of MoS2 are also contributory for HER catalysis. DFT calculations furthur confirmed that the high HER activity of this single atom catalyst is mainly owing to an ensemble effect via the synergy of Co adatom and S of the MoS2 support by tuning hydrogen-binding mode at the interface of the catalyst. The discovery of this SA Co-D 1T MoS2 catalyst highlights the area of tuning the structure and functionality of metal-TMD catalysts at the atomic scale, which holds great promise for applications in large scale water splitting electrolyzers.
This work cannot be done without the valuable collaborative efforts from Prof. Xiaoqiang Cui (Jilin University), Prof. Weitao Zheng (Jilin University), Prof. Shaojun Guo (Peking University), Prof. Lin Gu (Institute of Physics, CAS), Dr. Jingyuan Ma (Shanghai Institute of Applied Physics, CAS), Prof. Lirong Zheng (Institute of High Energy Physics, CAS), Prof. Wei Zhang (Jilin University) and Prof. Ping Liu (Brookhaven National Laboratory).
You can read more about the study in Nature Communications.
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1. Qi, K. et al. Single-atom cobalt array bound to distorted 1T MoS2 with ensemble effect for hydrogen evolution catalysis. Nature Communications. 10, 5231 (2019).