Water Oxidation by a Copper(II) Complex with 6,6?-Dihydroxy-2,2?-Bipyridine Ligand: Challenges and an Alternative Mechanism

Recently, copper(II) complexes have been exten-sively investigated as oxygen-evolution reaction (OER) catalysts through a water-oxidation reaction. Herein, new findings regarding OER in the presence of a Cu(II) complex with 6,6 '-dihydroxy-2,2 '- bipyridine ligand are reported. Using scanning electron micros-copy, energy dispersive spectrometry, X-ray diffraction, Raman spectroscopy, in situ visible microscopy, in situ visible spectroelec-trochemistry, X-ray absorption spectroscopy, and electrochemistry, it is hypothesized that the film formed on the electrode's surface in the presence of this complex causes an appropriated matrix to produce Cu (hydr)oxide. The resulting Cu (hydr)oxide could be a candidate for OER catalysis. The formed film could form Cu (hydr)oxide and stabilize it. Thus, OER activity increases in the presence of this complex.

Automated summary

Recently, there has been extensive research on copper(II) complexes as catalysts for the oxygen-evolution reaction. This study reports new findings on the oxygen-evolution reaction in the presence of a Cu(II) complex with a 6,6'-dihydroxy-2,2'-bipyridine ligand. Various techniques such as SEM, EDX, XRD, Raman spectroscopy, in situ visible microscopy, in situ visible spectroelectrochemistry, XAS, and electrochemistry were used to investigate the hypothesis that a film formed on the electrode's surface in the presence of this complex promotes the production of Cu(hydr)oxide, which can serve as a catalyst for OER. The formation of the film stabilizes Cu(hydr)oxide and enhances OER activity.