New Platinum Complexes from Salen- and Hydroxy-Substituted Salpn-Naphthalene Ligands with CO2 Reduction Activity

Abstract

The electrocatalytic reduction of carbon dioxide (CO2) into added-value products is a promising alternative to completing the cycle of atmospheric CO2. We report two new platinum complexes—a salen-like naphthalene (PtL1) and a hydroxy-substituted salpn naphthalene (PtL2)—that are capable of activating CO2 to produce carbon monoxide (CO). The predominant keto tautomer of the non-innocent ligands was determined using DFT calculations and UV-Vis spectroscopy. The PtL2 complex has a CO Faradaic efficiency >40% in the presence of water as a sacrificial proton source at −2.5 V vs. Fc/Fc+. The addition of the hydroxy group in combination with water as a proton source decreased the reduction potential and increased the CO formation tenfold when compared to PtL1.