Cationic cobalt(II) phthalocyanines as water soluble molecular electrocatalysts of carbon dioxide reduction

Capture and conversion of the emitted greenhouse gas carbon dioxide (CO2) has become a viable avenue of research to address the climate crisis. Molecular electrocatalysts have been extensively studied to facilitate the reduction of CO2 to high value products, but a competent catalyst has yet to emerge. Herein, tetracationic cobalt phthalocyanines (CoPc) are investigated as homogeneous catalysts for CO2 reduction in aqueous solutions, with an aim to fill the existing gap of literature in this research area. An in-depth analysis of trimethylammonium-phenoxy cobalt phthalocyanine iodide (CoPcI4(Me3NPhO)4) was undertaken using various electrochemical techniques, revealing the high efficiency of this catalyst for CO2 reduction. The unique and remarkable catalytic activity of this tetracationic CoPc inspired the intention to develop a new class of catalytic compounds to allow for direct and accurate comparisons. As a preliminary measure, trimethylethanolamine cobalt phthalocyanine iodide (TMAECoPc) was synthesised and analysed using electrochemical techniques to validate this concept.