RESUMO
In recent years, Fe-based catalysts for the selective catalytic reduction of NO with NH3 (NH3-SCR) have been attracting more attention. In this work, a novel Fe-Sb binary metal oxide catalyst was synthesized using the ethylene glycol assisted co-precipitation method and was characterized using a series of techniques. It was found that the catalyst with a molar ratio of 7:3 (Fe:Sb) displayed the best NH3-SCR activity with 100% conversion of NOx (nitrogen oxides) over a wide temperature window and with good resistance to H2O + SO2 at 250 °C. The X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) of NOx adsorption results suggested that strong electron interactions between Fe and Sb in Fe-O-Sb species existed and electrons of Sb could be transferred to Fe through the 2Fe3+ + Sb3+ â 2Fe2+ + Sb5+ redox cycle. The introduction of Sb significantly improved the adsorption behaviour of NOx species on the Fe0.7Sb0.3Ox surface, which benefitted the adsorption/transformation of NOx, thereby facilitating the NH3-SCR reaction. In addition, the Fe0.7Sb0.3Ox catalyst demonstrated a good tolerance of H2O and SO2, since the decomposition of NH4HSO4 on the catalyst surface was promoted by the introduction of Sb.
RESUMO
Invited for this month's cover is the group of Prof. Hyunwoong Park at the Kyungpook National University. The image shows the high-efficiency CO2 conversion to formate using multilayered porous dendrite Bi electrocatalysts. The Full Paper itself is available at 10.1002/cssc.201902581.
RESUMO
Facile synthesis of efficient electrocatalysts that can selectively convert CO2 to value-added chemicals remains a challenge. Herein, the electrochemical synthesis of porous Bi dendrite electrodes and details of their activity toward CO2 conversion to formate in aqueous solutions of bicarbonate are presented. The as-synthesized multilayered, porous, dendritic Bi electrodes exhibit a faradaic efficiency (FE) of approximately 100 % for formate production. Added halides and cations significantly influence the steady-state partial current density for formate production JFM (Cl- >Br- ≈I- ; Cs+ >K+ >Li+ ). DFT calculations revealed that the reaction pathway involving the species *OCOH occurs predominantly and the presence of both Cs+ and Cl- makes the overall reaction more spontaneous. Photovoltaic-cell-assisted electrocatalysis produced formate with an FE of approximately 95 % (JFM ≈10â mA cm-2 ) at an overall solar conversion efficiency of approximately 8.5 %. The Bi electrodes maintain their activity for 360â h without a change in the surface states.
RESUMO
To date, the in situ fabrication of the large-scale van der Waals multi-heterojunction transition metal dichalcogenides (multi-TMDs) is significantly challenging using conventional deposition methods. In this study, vertically stacked centimeter-scale multi-TMD (MoS2/WS2/WSe2 and MoS2/WSe2) thin films are successfully fabricated via sequential pulsed laser deposition (PLD), which is an in situ growth process. The fabricated MoS2/WS2/WSe2 thin film on p-type silicon (p-Si) substrate is designed to form multistaggered gaps (type-II band structure) with p-Si, and this film exhibits excellent spatial and thickness uniformity, which is verified by Raman spectroscopy. Among various application fields, MoS2/WS2/WSe2 is applied to the thin-film catalyst of a p-Si photocathode, to effectively transfer the photogenerated electrons from p-Si to the electrolyte in the photo-electrochemical (PEC) hydrogen evolution. From a comparison between the PEC performances of the homostructure TMDs (homo-TMDs)/p-Si and multi-TMDs/p-Si, it is demonstrated that the multistaggered gap of multi-TMDs/p-Si improves the PEC performance significantly more than the homo-TMDs/p-Si and bare p-Si by effective charge transfer. The new in situ growth process for the fabrication of multi-TMD thin films offers a novel and innovative method for the application of multi-TMD thin films to various fields.