Splitting water into hydrogen and oxygen is one of the most attractive scenarios for solar energy harvesting and sustainable energy production. One of the key challenges to water splitting is the development of efficient catalysts for the water oxidation half reaction with low overpotentials, good stability, and high turnover rates. Discovering efficient catalysts for the water oxidation reaction has rekindled great interest in recent years. Recently, copper-based water oxidation catalysts (WOCs) have attracted great interest with high current densities and good stabilities under basic conditions, but high overpotentials for water oxidation severely limit their practical utility. It is thus highly desirable to identify new strategies to lower overpotentials of these promising Cu-based WOCs.

Prof. Wenbin Lin’s group of Xiamen University reported the use of a ligand containing suitable pendant groups to mimic the functions of tyrosine Z in facilitating the oxidation of the Cu center to lead to a more active WOC. We designed a copper-based WOC with 6,6′-dihydroxy-2,2′-bipyridine (H2L) as the ligand, trying to mimic the role of tyrosine Z in Photosystem II by not only providing a redox-accessible ligand but also having the hydroxyl groups participating in the PCET processes, to lower the overpotential and enhance the WOC activity.(J. Am. Chem. Soc., 2013, DOI: 10.1021/ja409267p)