Solvothermal synthesis of spherical CoMnO₃ catalysts for efficient trace ethylene removal under high humidity

Trace ethylene, functioning as both a gaseous phytohormone and an atmospheric pollutant, requires efficient removal under humid conditions, which poses significant challenges for catalyst design. In this study, a series of spherical MnCoO_x oxides were synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted solvothermal method for trace ethylene oxidation under high humidity. The optimized Mn₅Co₂O_x catalyst exhibited superior low-temperature activity, achieving 90% ethylene conversion (T₉₀) at 174 °C under 95% relative humidity, along with excellent long-term stability over 100 h. A series of characterization studies revealed that Co incorporation promotes the formation of a perovskite-type CoMnO₃ phase and enhances the surface oxygen vacancy concentration. Furthermore, Co doping modulates the surface electronic states, enriching the key Mn⁴⁺ and Co³⁺ species, which synergistically improve the oxygen mobility and water tolerance. This work provides a rational strategy for designing efficient and water-resistant non-noble metal catalysts for trace ethylene removal in humid environments.