Construction of Spatial Effect from Atomically Dispersed Co Anchoring on Subnanometer Ru Cluster for Enhanced N<sub>2</sub>-to-NH<sub>3</sub> Conversion
Yangyu Zhang, Jiejie Li, Jihui Cai, Linlin Yang, Tianhua Zhang, Jianxin Lin, Xiuyun Wang, Chongqi Chen, Lirong Zheng, Chak‐Tong Au, Bo Yang, Lilong Jiang
Abstract
Simultaneously achieving a low activation barrier with weak binding of intermediates on a heterogeneous catalyst for the enhancement of catalytic performance under mild conditions remains a great challenge, especially for N2-to-NH3 conversion. Herein, for the first time, we report a new strategy via integrating vacuum-freeze-drying and high-temperature pyrolysis technologies to design atomically dispersed Co deposits onto the surface of Ru tiny subnanoclusters (TCs). The special structure of this catalyst can generate a spatial effect and induce strong interelectronic interactions between Ru and Co. The outcome is simultaneous generation of the high-surface-unoccupied Co 3d charge and obvious upshifting of the Ru d-band center. With that, there is lowering of N2 activation energy via strong electron “σ-donation and π-backdonation” between Ru and N2 molecules. More importantly, our studies demonstrate that an appropriate Ru structure with tiny subnanoclusters rather than single Ru atoms or large Ru clusters could enable the repulsion to adsorption of the N-containing intermediates on the catalyst surface, resulting in weakening of the binding of NH3 and N2H4 intermediates on the Co1Ru TC catalyst surface. In such a case, the scaling relation over Co1Ru TCs in NH3 synthesis was decoupled, and the developed Ba-promoted Co1Ru TC catalyst shows the highest NH3 synthesis rate (up to 21.90 mmolNH3 g–1 h–1 at 360 °C and 3 MPa) among the Ru or Co-based catalysts ever reported.