Oriented growth of δ-MnO2 nanosheets over core-shell Mn2O3@δ-MnO2 catalysts: An interface-engineered effects for enhanced low-temperature methanol oxidation

High-Throughput Screening Strategy for Electrocatalysts for Selective Catalytic Oxidation of Formaldehyde to Formic Acid

Electrocatalytic oxidation of formaldehyde (FOR) is an effective way to prevent the damage caused by formaldehyde and produce high-value products. A screening strategy of a single-layer MnO2-supported transition metal catalyst for the selective oxidation of formaldehyde to formic acid was designed by high-throughput density functional calculation. N-MnO2@Cu and MnO2@Cu are predicted to be potential FOR electrocatalysts with potential-limiting steps (PDS) of 0.008 and -0.009 eV, respectively. Electronic structure analysis of single-atom catalysts (SACs) shows that single-layer MnO2 can regulate the spin density of loaded transition metal and thus regulate the adsorption of HCHO (Ead), and Ead is volcanically distributed with the magnetic moment descriptor -|mM - mH|. In addition, the formula quantifies Ead and |mM - mH| to construct a volcano-type descriptor α describing the PDS [ΔG(*CHO)]. Other electronic and structural properties of SACs and α are used as input features for the GBR method to construct machine learning models predicting the PDS (R2 = 0.97). This study hopes to provide some insights into FOR electrocatalysts.

Tuning the crystallinity of the MnOx catalysts to promote toluene catalytic oxidation

In this paper, the MnOx catalysts with excellent toluene oxidation performance were prepared by a simple precipitation method. The physicochemical properties of the prepared MnOx catalysts were investigated by XRD, BET, H2-TPR, O2-TPD and XPS. The obtained results revealed that the crystallinity of the prepared MnOx catalysts could be effectively regulated by changing the (NH4)2CO3/Mn(NO3)2 molar ratio, and thus affecting the oxygen vacancy concentration of the prepared MnOx catalysts. The prepared MnOx-4 catalyst with the (NH4)2CO3/Mn(NO3)2 molar ratio of 4.0 had the poor crystallinity and small grain size, which effectively promoted the oxygen defects in the MnOx catalyst to be formed. At the same time, the MnOx-4 catalyst had a large specific surface area, the highest low temperature reducibility and the largest number of oxygen vacancies and surface adsorbed oxygen species, which allowed more surface oxygen species to participate in the redox reaction, and promoted the toluene deep oxidation. Therefore, when the (NH4)2CO3/Mn(NO3)2 molar ratio was 4.0, the prepared MnOx-4 catalyst exhibited an excellent toluene catalytic oxidation performance and robust catalytic stability. What's more, the toluene oxidation conversion on the MnOx-4 catalyst reached 99% at 230°C, and the MnOx-4 catalyst showed excellent resistance to water vapour.

Electrocatalytic Performance of MnMoO4-rGO Nano-Electrocatalyst for Methanol and Ethanol Oxidation

Today, finding low-cost electro-catalysts for methanol and ethanol oxidation with high performance and stability is one of the new research topics. A nanocatalyst based on metal oxides in the form of MnMoO₄ was synthesized by a hydrothermal method for methanol (MOR) and ethanol (EOR) oxidation reactions. Adding reduced graphene oxide (rGO) to the catalyst structure improved the electrocatalytic activity of MnMoO₄ for the oxidation processes. The crystal structure and morphology of the MnMoO₄ and MnMoO₄-rGO nanocatalysts were investigated by physical analyses such as scanning electron microscopy and X-ray diffraction. Their abilities for MOR and EOR processes in an alkaline medium were evaluated by performing electrochemical tests such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. MnMoO₄-rGO showed oxidation current densities of 60.59 and 25.39 mA/cm² and peak potentials of 0.62 and 0.67 V in MOR and EOR processes (at a scan rate of 40 mV/s), respectively. Moreover, stabilities of 91.7% in MOR and 88.6% in EOR processes were obtained from the chronoamperometry analysis within 6 h. All these features make MnMoO₄-rGO a promising electrochemical catalyst for the oxidation of alcohols.