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Journal of Electrochemistry ›› 2017, Vol. 23 ›› Issue (2): 180-198.doi: 10.13208/j.electrochem.161252

• Special Issue in Honor of Professor Zhaowu Tian on His 90th Birthday • Previous Articles     Next Articles

Green Electrochemical Ozone Production via Water Splitting: Mechanism Studies

Gregory Gibson1,2, Wenfeng Lin1*   

  1. 1. Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK; 2. School of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast, BT9 5AG, UK
  • Received:2017-03-01 Revised:2017-04-06 Online:2017-04-28 Published:2017-04-07
  • Contact: Wenfeng Lin E-mail:w.lin@lboro.ac.uk
  • Supported by:

    We gratefully acknowledge the Department of Education and Learning (DEL) of Northern Ireland, Northern Ireland Water Limited, Modern Water plc, UK EPSRC and Loughborough University for their supports.

Abstract:

The green and energy-efficient water splitting reaction using electrocatalysis for O3 formation provides a very attractive alternative to the conventional energy-intensive cold corona discharge (CCD) method. Among a large number of electrocatalysts explored for the electrochemical ozone production, β-PbO2 and SnO2-based catalysts have proven to be the most efficient ones at room temperature. In this study Density Functional Theory (DFT) calculations have been employed to investigate the possible mechanisms of ozone formation over these two types of catalysts. For both the β-PbO2 and Ni/Sb-SnO2 (nickel and antimony doped tin oxide) catalysts the (110) facet was found to be the most stable one. The possible water splitting mechanisms were modeled on both the β-PbO2(110) and Ni/Sb-SnO2(110) surfaces with particular attention given to the final two reaction steps, the formations of O2 and O3. For the β-PbO2, the formation of O3 was found to occur through an Eley-Rideal style mechanism as opposed to that on the Ni/Sb-SnO2, the latter occurs through a Langmuir-Hinshelwood style interaction. Thermodynamic parameters such as the adsorption energies (Eads), Gibbs free energies (ΔG) and activation energies (Eact) have also been obtained, compared and presented, with β-PbO2 being modelled primarily as solid-liquid phases and Ni/Sb-SnO2 modelled as gas phase. These DFT findings have provided the basis for a tool to design and develop new electrochemical ozone generation catalysts capable of higher current efficiencies.

Key words: ozone evolution reaction, water splitting, density functional theory, electrocatalysis, surface adsorption and reaction, lead oxide, nickel and antimony doped tin oxide