High-throughput Screening of Mechanically Interlocked Catenane Metal Complexes for Enhanced Electrocatalytic Activity

Metal complexes have been thoroughly investigated for a wide range of electrochemical reactions. However, mechanically interlocked molecular machines (MIM) have not been investigated for electrochemistry through a systematic high throughput screening. Here we introduce the concept of MIM Catenane metal complexes with a dynamic coordination environment around the metal center aimed towards enhanced CO2 reduction reaction (CO2RR), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and/or oxygen evolution reaction (OER). We applied density functional theory (DFT) to screen 3d transition metals supported by Catenane metal complexes denoted as M(II)CN6 and Co(I)CNX=4, 5, or 6. We found that among all the 3d transition metals, only monovalent Co(I) is suitable as an application as a molecular machine. We sought catalysts with high thermodynamic and electrochemical stabilities along with low CO2RR, ORR, OER, and HER overpotentials. We find that HER takes place on neighboring nitrogen atoms of Cu(II)CN6 with an overpotential of 0.27 V. Moreover, CO2RR, ORR, and OER take place on the metal active sites of Ti(II)CN6, Cr(II)CN6, and Co(II)CN6, with overpotentials of 1.12 V, 0.36 V, and 0.81 V, respectively. This paper provides fundamental insights into the design of advanced MIM catalysts by applying the concept of a dynamic coordination environment for electrochemistry at room temperature.