Engineering Inverse CuO@CeO ₂ Interfaces with Tandem Active Sites to Boost Low-Temperature Catalytic Degradation of Malodorous Methyl Mercaptan

Developing non-noble metal catalysts for ozone-free, low-temperature (<250 °C) catalytic degradation of highly toxic and malodorous sulfur-containing VOCs (methyl mercaptan, CH 3 SH) remains challenging due to the high C–S bond energy and mismatched diverse active sites. Herein, we engineer an inverse CuO@CeO 2 catalyst to realize the intimate coupling of CeO 2 nanoislands with an inverse Ce–O–Cu interfacial architecture. Experimental and theoretical calculations unveil that this specific geometric configuration integrates spatially adjacent vacancies and dual oxygen sites. Unlike conventional Cu–O–Ce interfaces that yield the dominant CH 4 by exposing CH x groups to the gas phase, our inverse Ce–O–Cu interface fundamentally manipulates intermediate orientations to synchronously drive multistep tandem reactions. Following initial CH 3 SSCH 3 formation at Ce-adjacent oxygen/vacancies, strong Cu–S binding anchors CH 3 S* via Cu-adjacent oxygen vacancies, which geometrically force the terminal CH x group to face the adjacent interfacial oxygen. Such spatial proximity drastically lowers the energy barrier for the key C–S cleavage and C–O coupling to generate CH 3 SCH 3 and CO 2 . Subsequent deep oxidation of CH 3 SCH 3 with CuO bulk lattice oxygen results in the formation of CO x, while sulfur is immobilized as a Cu x S reservoir. Consequently, the inverse catalyst achieves complete CH 3 SH conversion at 180 °C, outperforming state-of-the-art non-noble metal alternatives with zero emission of hazardous H 2 S. Critically, moisture is exploited to generate surface hydroxyls, providing the dual functions of active-site protection and oxygen compensation to boost sulfur tolerance. This work establishes a robust nanoisland-mediated inverse interfacial strategy for low-temperature S-VOCs purification without ozone assistance.