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Figure: Water splitting reaction using a copper catalyst

A ‘basic’ approach to water splitting as a promising way to store solar energy for on-demand use

The motivation Addressing the problem of storing energy for on-demand consumption is central to making use of solar energy when the sun isn’t shining. Water splitting is the conversion of two molecules of water to two molecules of dihydrogen and one molecule of dioxygen (i.e., 2H2O → 2H2 + O2). The resulting H2 and O2 can then be used in a fuel cell to generate electricity on-demand. The seemingly simple water splitting reaction is made up of two component reactions: O2 production (or water oxidation) and H2 production (or water reduction).

The discovery – In the Warren and Walsby research groups at Simon Fraser University, students recently developed a new approach for efficiently carrying out the water oxidation reaction using Earth-abundant copper catalysts. Inspired by the solar chemistry carried out by plants, they designed a simple way to synthesize a copper-containing molecule where water oxidation catalysis turns on under basic (alkaline) conditions. They investigated how the identity of these catalysts changes as the solution pH is made more alkaline and discovered a key change in catalyst identity that occurs under basic conditions. The resulting catalyst is highly active and carries out the water oxidation reaction under less demanding conditions than that required for related compounds.

Its significance – The characterization of how the copper complex changes with pH provides new concepts about how pH-responsive compounds or materials can be used to capture, convert, and store solar energy.

Read the paper“Lowering water oxidation overpotentials using the ionisable imidazole of copper(2-(2´-pyridyl)imidazole)” by Leea A. Stott, Kathleen E. Prosser, Ellan K. Berdichevsky, Charles J. Walsby and Jeffrey J. Warren. Chem. Commun. 53:651-654 (2017). DOI: 10.1039/C6CC09208J

Website article compiled by Jacqueline Watson with Theresa Kitos