Tailoring Dual High-Valence Cu–O–Mn Active Sites to Enhance VOC Catalytic Oxidation

Abstract

Advancing the catalytic oxidation of volatile organic compounds (VOCs) requires ongoingly boosting of both low-temperature activity and durability. Our strategy was to tailor suitable Cu-O-Mn coordination environments across numerous types of widely used CuMn bimetallic oxides. Unexpectedly, Cu-O-Mn sites within the CuO phase ignited greater catalytic activity toward alkanes like cyclohexane under 5.0% relative humidity, with a lower <i>T</i>₉₀ at 219 °C, and excellent stability over 48 h, compared to spinel phases noted for electron transfer. Doping CuO with high-valence Mn³⁺ and Mn⁴⁺ prefers to generate oxygen interstitials, facilitating the formation of dual high-valence Cu-O-Mn sites. Notably, optimal Cu₃Mn₁ simultaneously featured high-valence states of Cu^1.98+ and Mn^3.22+, as evidenced by the positive correlation between catalytic activity and valence state. Dual high-valence Cu-O-Mn sites within the CuO phase bolstered reactive oxygen species mobility, oxidizability, and replenishment, as well as acid sites, facilitating the Mars-van-Krevelen redox cycles. The resulting enhancement rapidly overcame the rate-limiting step of key intermediate benzene oxidation, endowing higher and sustainable reactivity. The superior performance could be validated through the catalytic oxidation of aromatics and alkenes represented by benzene and 1,3-butadiene, respectively. This work offers insights for catalyst design and promotes the practical application of CuMn bimetallic oxides in the VOC disposal.