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Surface lattice oxygen is crucial to the degradation of volatile organic compounds (VOCs) over transition metal oxides according to the Mars–van Krevelen mechanism. Herein, λ-MnO2in situ grown on the surface of CoMn spinel was prepared by acid etching of corresponding spinel catalysts (CoMn-Hx-Ty) for VOC oxidation. Experimental and relevant theoretical exploration revealed that acid etching on the CoMn spinel surface could decrease the electron cloud density around the O atom and weaken the adjacent Mn–O bond due to the fracture of the surface Co–O bond, facilitating electron transfer and subsequently the activation of surface lattice oxygen. The obtained CoMn-H1-T1 exhibited an excellent catalytic performance with a 90% acetone conversion at 149 °C, which is 42 °C lower than that of CoMn spinel. Furthermore, the partially maintained spinel structure led to better stability than pure λ-MnO2. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed a possible degradation pathway where adsorptive acetone converted into formate and acetate species and into CO2, in which the consumption of acetate was identified as the rate-limiting step. This strategy can improve the catalytic performance of metal oxides by activating surface lattice oxygen, to broaden their application in VOC oxidation.

The development of catalysts for volatile organic compound (VOC) treatment by catalytic oxidation is of great significance to improve the atmospheric environment. Size-effect and oxygen vacancy engineering are effective strategies for designing high-efficiency heterogeneous catalysts. Herein, we explored the in situ carbon-confinement-oxidation method to synthesize ultrafine MnOxnanoparticles with adequately exposed defects. They exhibited an outstanding catalytic performance with a T90of 167 °C for acetone oxidation, which is 73 °C lower than that of bulk MnOx(240 °C). This excellent catalytic activity was primarily ascribed to their high surface area, rich oxygen vacancies, abundant active oxygen species, and good reducibility at low temperatures. Importantly, the synthesized ultrafine MnOxexhibited impressive stability in long-term, cycling and water-resistance tests. Moreover, the possible mechanism for acetone oxidation over MnOx-NA was revealed. In this work, we not only prepared a promising material for removing VOCs but also provided a new strategy for the rational design of ultrafine nanoparticles with abundant defects.

The development of highly efficient and stable monolithic catalysts is essential for the removal of volatile organic compounds (VOCs). Copper foam (CF) is a potential ideal carrier for monolithic catalysts, but its low surface area is not conducive to dispersion of active species, thus reducing the interface interaction with active species. Herein, a vertically oriented Cu(OH)2nanorod was in situ grown on the CF, which acted as the template and precursor to synthesize CoCu-MOF. The optimized catalyst (12CoCu-R) delivers excellent performance for acetone oxidation with a T90of 195 °C. Impressively, the catalyst demonstrated satisfactory stability in long-term, cycle, water resistance, and high airspeed tests. Therefore, the present study provides a novel strategy for rationally designing efficient monolithic catalysts for VOC oxidation and other environmental applications.