Green Electrochemical Ozone Production via Water Splitting: Mechanism Studies

The green and energy-efficient water splitting reaction using electrocatalysis for Oformation provides a very attractive alternative to the conventional energy-intensive cold corona discharge (CCD) method. Among a large number of electrocat-alysts explored for the electrochemical ozone production, β-PbOand SnO-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-PbOand Ni/Sb-SnO(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-PbO(110) and Ni/Sb-SnO(110) surfaces with particular attention given to the final two reaction steps, the formations of Oand O. For the β-PbO, the formation of Owas found to occur through an Eley-Rideal style mechanism as opposed to that on the Ni/Sb-SnO, the latter occurs through a Langmuir-Hinshelwood style interaction. Thermodynamic parameters such as the adsorption energies (E^), Gibbs free energies (AG) and activation energies (Eact) have also been obtained, compared and presented, with /3-PbObeing modelled primarily as solid-liquid phases and Ni/Sb-SnOmodelled 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.