Green Electrochemical Ozone Production via Water Splitting: Mechanism Studies
- 2017年第23卷 
采用电催化剂通过水分解反应形成臭氧的绿色节能方法为常规耗能量大的冷电晕放电提供了非常具有吸引力的替代方法. 在大量研究的用于电化学合成臭氧的电催化剂中，β-氧化铅（β-PbO2）和氧化锡（SnO2）基催化剂在室温下最有效. 本工作通过密度泛函理论计算，研究了上述两种催化剂作用下臭氧的形成机制.两种催化剂β-PbO2和镍/锡掺杂氧化锡（Ni/Sb-SnO2）的(110) 晶面最稳定. 故作者特别关注β-PbO2(110) and Ni/Sb-SnO2(110)表面发生的最后两步反应，即氧气和臭氧的形成，模拟了可能的水分解机理. 结果表明，在β-PbO2催化剂的作用下，臭氧是遵循 Eley-Rideal机理形成，与在 Ni/Sb-SnO2,表面臭氧的形成机理相反，后者是通过Langmuir-Hinshelwood 机理形成. 将β-PbO2主要模拟为固-液相，Ni/Sb-SnO2主要模拟为气相，计算得到吸附能(Eads)、吉布斯自由能(ΔG)和活化能(Eact)等热力学参数值，并进行了分析与比较. 这些结果为设计和研发新型的高电流效率电化学制臭氧用催化剂提供了依据.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.