Mixed-Metal Semiconductor Anodes for Electrochemical Water Splitting and Reactive Chlorine Species Generation: Implications for Electrochemical Wastewater Treatment

Abstract

A procedure for the preparation of semiconductor anodes using mixed-metal oxides bound together and protected with a TiO_2 nanoglue has been developed and tested in terms of the relative efficiencies of the oxygen evolution (OER), the reactive chlorine species evolution (RCS), and the hydrogen evolution (HER) reactions. The composition of the first anode is a Ti metal substrate coated with IrTaO_x and overcoated with TiO_2 (P_(25)) that was mixed with TiO_2 nanogel, while the second anode consists of a Ti metal substrate coated with IrTaO_x and an over-coating layer of La-doped sodium tantalate, NaTaO_3:La. The experimental efficiencies for water splitting ranged from 62.4% to 67.5% for H_2 evolution and 40.6% to 60.0% for O_2 evolution. The corresponding over-potentials for the Ti/IrTa-TiO_2 and Ti/IrTa-NaTaO_3:La anodes coupled with stainless steel cathodes of the same dimensions were determined to be 437 mV and 367 mV for the OER, respectively, and 239 mV and 205 mV for RCS, respectively. The preparation procedure described herein should allow for easier production of large-surface area anodes at lower costs than standard methods.

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