Enhanced Catalytic Performance of La-Doped CoMn₂O₄ Catalysts by Regulating Oxygen Species Activity for VOCs Oxidation

Abstract

Tuning the oxygen species activity of transition metal oxide catalysts is essential for harnessing environmental catalytic oxidation reactions, and the mobility of lattice oxygen and activation ability of gas oxygen over CoMn2O4 were well modulated by in situ solvothermal-induced lanthanum doping for VOCs oxidation. Lanthanum species were successfully doped into the spinel lattice, and the toluene oxidation rate of Co1Mn1.9La0.1 increased by 20.74 times compared with that of the undoped Co1Mn2 catalyst at 220 °C. With lanthanum doping, the content of oxygen vacancies was remarkably increased (1.4-fold) due to oxygen atoms in unusual bonding situations. Higher mobility and reactivity of lattice oxygen species were achieved by weakening the metal–oxygen bond strength, favoring the conversion of toluene to CO2 and H2O. Furthermore, doping lanthanum into the spinel lattice also promoted the activation and replenishment of gas oxygen. Moreover, the oxidation of anhydride species, as a rate-determining step, could be significantly accelerated due to lanthanum doping. This work provided a credible comprehension of the regulation of spinel oxygen species by lanthanum doping in VOCs abatement to improve the atmospheric environment.

Universal synthesis of rare earth-doped FeP nanorod arrays for the hydrogen evolution reaction

“…Sm with a flexible 4f-subshell electron configuration and the strong spin–orbital effect can significantly decrease the formation energy of vacancies, which may result in the vacancy-rich feature of Sm-FeP@CC. 62,63…”

Tailoring oxygen vacancies and active surface oxygen species in CrOx hierarchical strawberry-type three-dimensional (3D) micro-spindle catalysts for total catalytic oxidation of VOCs

“…Importantly, the first peak ( I ) at around ∼220 °C (Fig. 6a), which is mainly ascribed to the reduction of the surface oxygen species, which is attributed to the extraction process of surface lattice oxygen species by H 2 , 37 was obviously augmented using the Cr 6+ precursor. Therefore, it is very obvious that the product obtained after calcining ammonium dichromate at 750 °C (CrO x AH ) exhibits a high peak owing to reduction of the surface oxygen species.…”

Ultrathin LayCoOx Nanosheets with High Porosity Featuring Boosted Catalytic Oxidation of Benzene: Mechanism Elucidation via an Experiment–Theory Combined Paradigm

“…18−21 Among them, the MVK mechanism is particularly suitable for TMO-based catalysts. 22,23 The MVK mechanism comprises two primary steps: in the first, VOC molecules react with surface-bound reactive oxygen species (ROS), leading to catalyst reduction; in the second, the catalyst interacts with gaseous-phase oxygen to replenish the consumed ROS, thus reverting the reduced catalyst to its initial state. 24−26 Throughout this process, the rates of reduction and oxidation govern the overall catalytic performance of the catalysts.…”

“…In the field of catalytic benzene oxidation, the search for and development of highly efficient catalysts with superior oxidation activity and stability represent fundamental challenges. , In comparison to noble-metal-supported catalysts, transition-metal oxides (TMOs) offer distinct advantages such as abundant resources and lower costs, positioning them as promising alternatives. − The creation of such desirable catalysts hinges on a profound understanding of the catalytic mechanisms involved. Mars-van Krevelen (MVK), Langmuir–Hinshelwood (L–H), and Eley–Rideal (E–R) are three commonly employed mechanisms to elucidate the intricate processes of catalytic volatile organic compounds (VOCs). − Among them, the MVK mechanism is particularly suitable for TMO-based catalysts. , The MVK mechanism comprises two primary steps: in the first, VOC molecules react with surface-bound reactive oxygen species (ROS), leading to catalyst reduction; in the second, the catalyst interacts with gaseous-phase oxygen to replenish the consumed ROS, thus reverting the reduced catalyst to its initial state. − Throughout this process, the rates of reduction and oxidation govern the overall catalytic performance of the catalysts. Consequently, maintaining a stable catalyst surface is of paramount importance to achieve uncompromised catalytic durability and stability .…”