High-throughput screening of mechanically interlocked Catenane metal complexes for enhanced electrocatalytic activity†

Abstract

Metal complexes have been thoroughly studied for various electrochemical reactions. Mechanically interlocked molecular machines, however, have not been studied for electrochemistry. In this study, we apply the concept of mechanically interlocked Catenane metal complexes with a dynamic coordination environment around the metal center for the hydrogen evolution reaction (HER), CO₂ reduction reaction (CO₂RR), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). We utilized density functional theory (DFT) to perform a systematic high-throughput screening on 3d transition metals supported by Catenane metal complexes denoted as M(II)_CN6 and Co(I)_CNx=4,5,6. Our findings reveal that among all 3d transition metals, only monovalent Co(I) exhibits the potential for application as a molecular machine. Target catalysts aimed at high electrochemical as well as thermodynamic stabilities along with low HER, CO₂RR, OER, and ORR overpotentials. DFT results show that HER takes place on neighboring nitrogen atoms of Cu(II)_CN6 with an overpotential of 0.27 V. In addition, CO₂RR, OER, and ORR take place on the metal-active sites of Ti(II)_CN6, Co(II)_CN6, and Cr(II)_CN6, with overpotentials of 1.12, 0.81, and 0.36 V, respectively. This work brings fundamental understandings into the discovery of state-of-the-art electrocatalysts by introducing the idea of a dynamic coordination environment.