Applied Catalysis A--General (特集 触媒研究と学術雑誌/情報)

3D-MoS2 can adsorb organic molecules and provide multidimensional electron transport pathways, implying a potential application for environment remediation. Here, we study the degradation of aromatic organics in advanced oxidation processes (AOPs) by a 3D-MoS2 sponge loaded with MoS2 nanospheres and graphene oxide (GO). Exposed Mo4+ active sites on 3D-MoS2 can significantly improve the concentration and stability of Fe2+ in AOPs and keep the Fe3+ /Fe2+ in a stable dynamic cycle, thus effectively promoting the activation of H2 O2 /peroxymonosulfate (PMS). The degradation rate of organic pollutants in the 3D-MoS2 system is about 50 times higher than without cocatalyst. After a 140 L pilot-scale experiment, it still maintains high efficiency and stable AOPs activity. After 16 days of continuous reaction, the 3D-MoS2 achieves a degradation rate of 120 mg L-1 antibiotic wastewater up to 97.87 %. The operating cost of treating a ton of wastewater is only US$ 0.33, suggesting huge industrial applications.

Designing 3D-MoS 2 Sponge as Excellent Cocatalysts in Advanced Oxidation Processes for Pollutant Control.

Atomic‐Level Reactive Sites for Semiconductor‐Based Photocatalytic CO2 Reduction

CO2 hydrogenation to methanol over Cu/ZrO2 catalysts: Effects of zirconia phases

We report single-atom Cu catalysts dispersed on nitrogen-doped carbon by a nitrogen-coordination strategy. The presence of nitrogen enabled good dispersion and attachment of atomic Cu species on th...

Boosting CO2 Electroreduction to CH4 via Tuning Neighboring Single-Copper Sites

XAFS at the copper K-edge has been recorded for cuprous oxide and cupric oxide separately and also for a mixture of the two in a specific ratio, at the XAFS beam line at SSRL. The normalized μ(E) data obtained for the two oxides, i.e., Cu(I) and Cu(II) oxides separately was linearly combined to fit the normalized μ(E) data of the mixture using the Linear Combination Fitting (LCF) method. The values obtained for the statistical goodness-of-fit parameters, R-factor and chi-square, show that the fit is reasonably good. This procedure yielded the percentage of the oxides in the mixture which was found to be nearly the same as the actual percentage which was used to prepare the mixture. Another method based on the analysis of normalized difference absorption edge spectra has also been used to quantitatively determine the percentage of the two copper species in the mixture. The LCF method is, however, found to be better than the normalized difference absorption edge analysis.

https://iopscience.iop.org/article/10.1088/1742-6596/190/1/012084/pdf

Copper K-edge XANES of Cu(I) and Cu(II) oxide mixtures

Atomically dispersed atom catalysts with atomically distributed active metal centers have attracted great attention owing to the maximum atom efficiency and excellent selectivity. Herein, for the first time, we found atomically dispersed Mo atoms can be formed on g-C3N4, and induce its amorphous transformation. This amorphous transformation leads to the formation of strong band tails with remarkably enhancing the absorbance edge of Mo-C3N4 up to 750 nm, resulting in almost whole visible-light range absorption. The formation of new Mo-C and Mo-N bonds due to strong interfacial interaction between atomically dispersed Mo atoms and g-C3N4 provide new electron and hole transport pathways to accelerate the separation of charge carriers. As a result, amorphous Mo/C3N4 (a-Mo/C3N4) reveals excellent photoreduction of CO2, yielding CO and H2 productions of 18 and 37 μmol g−1 h−1 under visible-light illumination (λ > 420 nm), which manifest a remarkable 10.6- and 4-folds enhancement of that over crystalline g-C3N4. This finding provides a conceptually different approach to fabricate high-efficient photocatalyst through the strong interfacial interaction between atomically dispersed metal atoms and host.

Atomically dispersed Mo atoms on amorphous g-C3N4 promotes visible-light absorption and charge carriers transfer

Determination of the chemical forms along with the relative quantity of the di erent species in a given sample, termed as speciation, can be done by analyzing X-ray absorption ne structure spectra. The di erent methods that can be used for speciation are: principal component analysis, target transformation, methods based on derivative spectra, method based on the relative position of the absorption edge, residual phase analysis, normalized di erence absorption edge spectra analysis and linear combination tting. An attempt has been made to make a comparative study of these di erent methods of speciation by recording the X-ray absorption ne structure at the copper K-edge in a mixture having cuprous oxide and cupric oxide in a speci c ratio. The X-ray absorption ne structure spectra of the two oxides have also been recorded separately and the di erent characteristic X-ray absorption near edge structure features have been identi ed and their origins have been discussed. Speciation of the mixture has been done using these di erent methods and the results obtained have been compared and discussed.

/pdf/a-comparative-study-of-the-methods-of-speciation-using-x-ray-246s386u82.pdf

A Comparative Study of the Methods of Speciation Using X-ray Absorption Fine Structure

https://pubs.rsc.org/en/content/articlepdf/2020/CY/D0CY01396J

Structural dynamics in Ni–Fe catalysts during CO2 methanation – role of iron oxide clusters

Ultrasmall Au, Pd, and AuPd nanoparticles (NPs) stabilized by PVP were prepared in a microfluidic reactor with cyclone micromixers for rapid mixing of reactants. In this system, pulsation-free flow of reactants was achieved at a total flow rate of 2.6 L h–1. A rapid homogeneous mixing within 2 ms was obtained with three cyclone micromixers. Controlled NP nucleation and growth occur in a following meandering microchannel. The resulting colloidal NPs were characterized thoroughly by various complementary techniques, e.g., high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), and ultraviolet–visible spectroscopy. The average NP diameter was about 1 nm with a narrow size distribution, and electron microscopy showed homogeneously alloyed NPs. Moreover, the particles were supported on TiO2 for catalytic tests and further structural characterization. Electron microscopy showed a uniform distribution of NPs on the support with some aggregation. X-ray absorption spec...

Abhijeet Gaur

Papers

Copper K-edge XANES of Cu(I) and Cu(II) oxide mixtures

Atomically dispersed Mo atoms on amorphous g-C3N4 promotes visible-light absorption and charge carriers transfer

A Comparative Study of the Methods of Speciation Using X-ray Absorption Fine Structure

Structural dynamics in Ni–Fe catalysts during CO2 methanation – role of iron oxide clusters

Microfluidic Synthesis of Ultrasmall AuPd Nanoparticles with a Homogeneously Mixed Alloy Structure in Fast Continuous Flow for Catalytic Applications