A Biomimetic Copper Water Oxidation Catalyst with Low Overpotential

Abstract

Simply mixing a Cu(II) salt and 6,6'-dihydroxy-2,2'-bipyridine (H2L) in a basic aqueous solution afforded a highly active water oxidation catalyst (WOC). Cyclic voltammetry of the solution at pH = 12-14 shows irreversible catalytic current with an onset potential of ~0.8 V versus NHE. Catalytic oxygen evolution takes place in controlled potential electrolysis at a relatively low overpotential of 640 mV. Experimental and computational studies suggest that the L ligand participates in electron transfer processes to facilitate the oxidation of the Cu center to lead to an active WOC with low overpotential, akin to the use of the tyrosine radical by Photosystem II to oxidize the CaMn4 center for water oxidation.

Single Electron Transfer Steps in Water Oxidation Catalysis. Redefining the Mechanistic Scenario

“…1 top and an I2M mechanism is found when the favored species resemble those of the oxyl radical form depicted in the lower part of Figure 1 Recently several first row transition metal complexes have been reported as catalysts for the water oxidation reaction. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] While these catalysts are of interest because of their high abundance and low toxicity, their performance is much poorer than their Ru or Ir analogues, and in addition their mechanistic pathways are in most cases basically unknown. [28][29][30][41][42][43] We have very recently reported a new complex based on Cu, containing the amidate ligand OPBAN that can carry out the water oxidation reaction in a very efficient manner.…”

Electrocatalytic water oxidation by CuII complexes with branched peptides

“…Modification of Cu II (bpy)(OH) 2 by using 6,6 0 -dihydroxybpy demonstrated the potential of tuning such systems toward better efficiency (e.g., reduced overpotential) by aiding proton channelling. 14 The modularity of peptides opens even more options to affect the catalytic properties from the ligand side. Experimental information is presented below in support of water oxidation electrocatalysis at elevated pH in the presence of Cu complexes with two different dap-based peptides: H-Gly-Dap(H-Gly)-Gly-NH 2 (3G) and H-Gly-Dap(H-Gly)-His-NH 2 (2GH) (Scheme 1).…”

Analysis of Trends and Emerging Technologies in Water Electrolysis Research Based on a Computational Method: A Comparison with Fuel Cell Research

“…In cluster III-8, different Cu complexes exhibit high OER activity [88,89]. These studies indicate that Cu can be a promising catalyst for HER as it is abundant and low cost, although, for practical use, Cu complexes should be developed as an electrode, or a heterogeneous Cu compound would need to be developed.…”