Engineering Inverse CuO@CeO2 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, CH3SH) remains challenging due to the high C-S bond energy and mismatched diverse active sites. Herein, we engineer an inverse CuO@CeO2 catalyst to realize the intimate coupling of CeO2 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 CH4 by exposing CHx groups to the gas phase, our inverse Ce-O-Cu interface fundamentally manipulates intermediate orientations to synchronously drive multistep tandem reactions. Following initial CH3SSCH3 formation at Ce-adjacent oxygen/vacancies, strong Cu-S binding anchors CH3S* via Cu-adjacent oxygen vacancies, which geometrically force the terminal CHx 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 CH3SCH3 and CO2. Subsequent deep oxidation of CH3SCH3 with CuO bulk lattice oxygen results in the formation of COx, while sulfur is immobilized as a CuxS reservoir. Consequently, the inverse catalyst achieves complete CH3SH conversion at 180 °C, outperforming state-of-the-art non-noble metal alternatives with zero emission of hazardous H2S. 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.