Effective Ensemble of Pt Single Atoms and Clusters over the (Ni,Co)(OH)<sub>2</sub> Substrate Catalyzes Highly Selective, Efficient, and Stable Hydrogenation Reactions
Lihua Zhu, Yilun Sun, Huaze Zhu, Guoliang Chai, Zhiqing Yang, Congxiao Shang, Hengqiang Ye, Bing Hui Chen, Anna Kroner, Zhengxiao Guo
Abstract
A Pt–Ni–Co catalyst was synthesized with Pt single atoms and atomic clusters (SAACs) dispersed over (Ni,Co)(OH)2 nanoparticles on a carbon matrix, which leads to high catalytic activity, up to 100% conversion, and selectivity in the hydrogenation of nitroaromatics under moderate conditions (H2 ∼ 1.0 MPa and ≤40 °C). A synergistically coordinated ensemble effect of the Pt SAACs is identified with the strongly polarized Pt single atoms preferentially adsorbing the −NO2 and the Pt clusters adsorbing and homolytically dissociating H2 molecules, and the H species then readily move to the adsorbed −NO2 group, overcoming a much reduced energy barrier on the (Ni,Co)(OH)2, enhancing the reaction rate by ca. 50 times. The approach not only reveals the coordinated ensemble catalysis mechanism of SAACs but also provides a strategy of developing highly efficient and selective catalysts by fine tuning of the electronic microenvironment from single atoms to atomic clusters co-located over a multimetallic substrate. The demonstrated case for nitroarenes can be readily applied for other species containing −NO2 or other easily hydrogenated groups (such as C═C, C≡N, and C═O).