Development of Transition Metal Phosphine Complexes as Electrocatalysts for CO₂ and CO Reduction

Abstract

[Pd(triphosphine)(solvent)](BF₄)₂ complexes have been developed as catalysts for the electrochemical reduction of CO₂ to CO. A variety of structural features of these complexes have been varied to determine their effects on the mechanism, rates, and decomposition products of these catalysts. The structural features varied included substituents on the triphosphine ligand, the size of the chelate bite, and donor atoms of the tridentate ligand. Bimetallic catalysts containing two [Pd(triphosphine)(solvent)] units have been prepared and characterized that exhibit a cooperative interaction during CO₂ reduction with large rate enhancements compared to their monomeric analogs. As a first step in developing electrocatalysts capable of reducing CO, electrochemically generated hydrides of Ni and Pd have been shown to transfer their hydride ligands to coordinated CO to form formyl complexes.

Key Words:

• carbon dioxide reduction
• electrocatalysis
• metal phosphine complexes
• cooperative effects
• formyl complexes