Tuning Lewis acid in nickel-containing polyoxometalates for enhanced ethanol selectivity of methane electrooxidation reactions
Jvwei Liu, Qiang Zhang, Conglin Chen, Shenjie Zhang, Jiaxin Jiang, Junqiang Xu
Abstract
Abstract The electrocatalytic oxidation of methane (CH4) facilitates the direct conversion of abundant natural gas into value-added chemicals utilizing renewable electricity. However, the high dissociation energy of the C–H bond and the presence of multiple competing reaction pathways lead to poor product selectivity. We synthesized a Ni-based polyoxometalate (Ni-POM-VO) through cluster-nucleus co-assembly and introduced rich oxygen vacancies using N2 cold plasma etching. The optimized catalyst attained a Faradaic efficiency of 88.4% for ethanol at 1.7 V versus the reversible hydrogen electrode (RHE). Notably, the oxygen vacancies in Ni-POM-VO create Lewis acid sites that enhance methane adsorption and activation, thereby facilitating its conversion into *CH2 and *CH2OH intermediates. The subsequent adsorption of these intermediates onto the polyoxometalate (POM) framework promotes C–C coupling, resulting in ethanol production. This work provides a new method for adjusting the Lewis acid content on the catalyst surface through oxygen vacancies, improving the selectivity of methane electro oxidation to ethanol.