Abstract
Single-atom catalysts (SACs) as the new frontier in heterogeneous catalysis have attracted increasing attention. However, the rational design of SACs with high catalytic activities for specified reactions still remains challenging. Herein, we report the rational design of a Pd(1)-Pd(NPs) synergistic structure on 2,6-pyridinedicarbonitrile-derived covalent triazine framework (CTF) as an efficient active site for CO(2) hydrogenation to formate under ambient conditions. Compared with the catalysts mainly comprising Pd(1) and Pd(NPs), this hybrid catalyst presented significantly improved catalytic activity. By regulating the ratio of Pd(1) to Pd(NPs), we obtained the optimal catalytic activity with a formate formation rate of 3.66 mol(HCOOM)·mol(Pd) (-1)·h(-1) under ambient conditions (30°C, 0.1 MPa). Moreover, as a heterogeneous catalyst, this hybrid catalyst is easily recovered and exhibits about a 20% decrease in the catalytic activity after five cycles. These findings are significant in elucidating new rational design principles for CO(2) hydrogenation catalysts with superior activity and may open up the possibilities of converting CO(2) under ambient conditions.