- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Structural transformation identification of sputtered amorphous MoS <sub/>x</sub> as efficient hydrogen evolving catalyst during electrochemical activation
摘要： Molybdenum sulfide MoSx is considered as attractive hydrogen evolution catalyst since it is free of noble metals and shows a low overpotential. Especially, amorphous molybdenum sulfide has attracted attention because of its high catalytic activity. However, the catalytic mechanism of the hydrogen evolution reaction is not yet fully understood. Therefore in our study, layers of MoSx were deposited by reactive magnetron sputtering varying the substrate temperature in the range from room temperature (RT) to 500°C. The morphology and structure of the films change significantly as a function of temperature, from an amorphous to a highly textured 2H-MoS2 phase. The highest catalytic activity was found for amorphous layers deposited at RT showing an overvoltage of 180 mV at a current density of -10 mAcm-2 in a 0.5 M sulfuric acid electrolyte (pH 0.3) after electrochemical activation. As detected by Raman spectroscopy the RT deposited catalyst consists of [Mo3S13]2- and [Mo3S12]2- entities which are interconnected via [S2]2- and S2- ligands. When sweeping the potential from 0.2 to -0.3 V vs RHE a massive release of sulfur in form of gaseous H2S was observed in the first minutes as detected by differential electrochemical mass spectroscopy (DEMS). After electrochemical cycling for 10 min, the chains of these clusters transform into a layer-type MoS2-x phase observed by in-situ Raman spectroscopy. In this transformation process, H2S formation gradually vanishes and H2 evolution becomes dominant. The transformed phase is considered as a sulfur deficient molybdenum sulfide characterized by a high number of molybdenum atoms located at the edges of nano-sized MoSx islands, which act as catalytically active centers.
关键词： hydrogen evolving catalyst,structural transformation,water splitting,molybdenum sulfide,sputtering
更新于2025-09-19 17:15:36
-
Enhancing photocatalytic activity of tantalum nitride by rational suppression of bulk, interface and surface charge recombination
摘要： Rational design of photocatalysts is essential to achieve efficient solar energy conversion. For narrow bandgap Ta3N5 photocatalyst, various charge recombination occurring in the bulk, interface and on the surface significantly impairs its activity for solar hydrogen (H2) generation. Herein, a synergistic engineering approach is designed to solve this critical recombination challenge. First, hollow spherical structure of Ta3N5 with Mg doping is prepared to not only reduce the charge migration distance and increase the surface area, but also increase the electron mobility for facilitated charge transfer. Second, an MgO nano-layer covers the surface of hollow Ta3N5 structure to passivate surface defects, thus promoting the interfacial charge transfer between Ta3N5 and co-catalysts. Finally, dual co-catalysts (Pt/CoOx) for redox reactions are loaded onto the hollow Ta3N5 structure to reduce the surface recombination and overcome the sluggish surface reaction. Remarkably, the combination of hollow structure, Mg2+ doping, MgO interfacial layer, and dual co-catalysts effectively improves the charge separation and transfer in Ta3N5 photocatalyst. This newly designed photocatalyst exhibits a considerably improved H2 generation performance of 56.3 μmol h-1 under simulated sunlight, compared to that of reference Pt/Ta3N5 hollow spheres.
关键词： doping,hollow structure,co-catalyst,surface passivation,tantalum nitride
更新于2025-09-19 17:15:36
-
Effects of Electrospinning Solution Properties on Formation of Beads in Tio2 Fibers with PdO Particles
摘要： TiO2 fibers with catalytic PdO particles are of interest for use as porous catalytic converters to react NOx and CO to control air pollution. The fibers are first electrospun as template polymer fibers. The template polymer fibers are calcined to form the ceramic fibers. The electrospinning solution composition significantly affects fiber morphologies (beads) which in turn affect the catalyst performance. In this work, solutions containing Polyvinylpyrrolidone (PVP), Titanium (IV) Isopropoxide (TTIP), and Palladium (II) Chloride (PdCl2) were electrospun with the goal of fabricating beadless submicron composite fibers. The fibers were calcined to produce ceramic TiO2 submicron fibers with Palladium oxide (PdO) nanoparticles. To determine the solution recipes that form smooth PdO-TiO2 fibers without beads, fibers were electrospun and evaluated from solutions with varied mass concentrations of PVP and PdCl2 salt. The solution concentrations indirectly influenced the electrospinning performance through solution viscosity, surface tension and electrical conductivity. The ceramic fibers were produced with average diameters in the range of 180-280 nm and with minimal formation of beads when the solution had viscosity in the range of 52 to 80 cP and conductivity in the range of 45-67 μs/cm. It was found that the surface tension of the solutions did not vary significantly and did not strongly affect the formation of beads.
关键词： nanofiber,beads,Electrospinning,catalyst support,ceramic
更新于2025-09-19 17:15:36
-
An ultrasound-assisted photocatalytic treatment to remove an herbicidal pollutant from wastewaters
摘要： Pollutants of emerging concern contaminate surface and ground water. Advanced oxidation processes treat these molecules and degrade them into smaller compounds or mineralization products. However, little information on coupled advanced oxidation techniques and on the degradation pathways of these pollutants is available to identify possible ecotoxic subproducts. In the present work, we investigate the ultrasound assisted photocatalytic degradation pathway of the herbicide Isoproturon. We worked in batch mode in a thermostatic glass reactor. We compared the activity of nanometric TiO2 P25 with that of Kronos 1077, a micrometric TiO2. We discuss the individual, additive and synergistic degradation action of photolysis, sonolysis, sonophotolysis, and sonophotocatalysis by varying catalyst loading and/or ultrasound power for the last three techniques. With 0.1 g L?1 catalyst, photocatalysis and sonophotocatalysis completely degrade Isoproturon within 240 min and 60 min, respectively (> 99 % conversion). Sonophotocatalysis breaks Isoproturon down into smaller molecules than photocatalysis alone.
关键词： degradation pathway,wastewater treatment,Isoproturon,sonophotodegradation,micrometric catalyst
更新于2025-09-19 17:15:36
-
Controllable Synthesis of Special Reed-Leaf-Like Carbon Nanostructures Using Copper Containing Catalytic Pyrolysis for High-Performance Field Emission
摘要： Special reed-leaf-like carbon nanostructures have been realized by using chemical vapor deposition (CVD) under the combined action of copper containing catalytic pyrolysis and ammonia (NH3) gas. The nucleation and growth mechanisms of CNLs based on growth parameters are discussed. The Raman spectra of carbon nanotubes (CNTs), CNLs and CNT-CNL composites were measured and found to be strongly influenced by the type of gas. Field emission (FE) properties of CNL-CNT composites were observed with a lower turn-on electric field of 0.73 V/μm, and a higher current density of 18.0 mA/cm2 at an electric field of 2.65 V/μm, which are superior to those of CNTs and flower-like CNLs. This is because there are more field emitters in CNLs inter-planted in CNTs. We consider that the unique FE stability of CNTs and defects in CNLs play a synergetic role on the improved FE properties.
关键词： carbon nanostructure,catalytic pyrolysis,field emission properties,copper catalyst
更新于2025-09-19 17:15:36
-
Growth of single crystalline GePb film on Ge substrate by magnetron sputtering epitaxy
摘要： A novel direct synthesis of 1,3-dioxo-substituted allenes was developed by copper(I)-catalyzed coupling of a-oxo-alkynes and a-oxo-diazos. It was a sequence of adding substrates-controlled method and the desired products were synthesized chemoselectively by adding a-oxo-alkyne terminally.
关键词： Alkynes,Cross-coupling,Allenes,Copper catalyst,Diazo compounds
更新于2025-09-19 17:15:36
-
Synthesis of Cu2O/Carbon film/NiCoB-GO Heterostructure Photocathode for Efficient Photoelectrochemical Water Splitting
摘要： Photoelectrochemical (PEC) water splitting offers a promising way to convert solar energy to chemical energy. The electron transfer rate and surface-catalyzed ability toward hydrogen evolution reaction (HER) play the key roles in the efficiency of PEC water splitting. In this work, a Cu2O/Carbon film/NiCoB-GO heterostructure photocathode is fabricated. Among them, thickness-controllable carbon film served as the electron transport and protective layer with favourable optical property, NiCoB-GO amorphous catalyst displays the efficient performance towards HER in neutral condition. The optimized photocathode shows the PEC-HER performance with a photocurrent density of -2.9 mA/cm2 at 0 V vs. RHE, and it also presents better stability than bare Cu2O. This work provides a novel heterostructure photocathode for promoting solar-driven PEC water splitting efficiently.
关键词： Femtosecond transient absorption spectroscopy,Photoelectrochemical water splitting,Electron transport path,Carbon film,Amorphous catalyst
更新于2025-09-19 17:15:36
-
Application of an electron-transfer catalyst in light-induced aerobic oxidation of alcohols
摘要： The first heterogeneous photocatalysis system including a bipyridinium-based complex as the electron-transfer catalyst was developed for aerobic oxidation of alcohols without the use of any noble-metal, external N-oxide or peroxide co-oxidant. The current work provides an efficient strategy for alcohol oxidation through a cost-effective, convenient and eco-friendly route.
关键词： bipyridinium complex,aerobic oxidation,heterogeneous photocatalysis,alcohols,electron-transfer catalyst
更新于2025-09-19 17:15:36
-
Are Nano-Composite Coatings the Key for Photovoltaic Panel Self-Maintenance: An Experimental Evaluation
摘要： This article shows the in?uence of an anti-fouling nano-coating on the electrical energy produced by a string of photovoltaic modules. The coating effect was evaluated comparing the energy produced by two strings of the same PV power plant: one of them was cleaned and the other was cleaned and treated with the coating before the monitoring campaign. The PV plant is located in Modena, north of Italy. A ?rst monitoring campaign of nine days after the treatment shows that the treatment increases the energy production on the PV arrays by about 1.82%. Results indicate that the increase is higher during sunny days with respect to cloudy days. A second monitoring campaign of the same length, but ?ve months later, shows that the energy gain decreases from 1.82% to 0.69% due to the aging of the coating, which is guaranteed for one year by the manufacturer. A technical-economical analysis demonstrates that at the moment the yearly economic gain is 0.43 e per square meter of panel and the cost of the treatment is about 1 e per square meter. However, large scale diffusion can reduce the production cost and thus increase the affordability of the coating.
关键词： hydrophilic,antistatic,photovoltaic,optical losses,photo-catalyst
更新于2025-09-19 17:15:36
-
Hierarchical Ni-MoSex@CoSe2 core-shell nanosphere as highly active bifunctional catalyst for efficient dye-sensitized solar cell and alkaline hydrogen evolution
摘要： Core-shell structured nanocomposites based on transition metal selenides have a broad development prospect as Pt-free electrocatalyst in energy conversion due to large surface area, rich edge sites, as well as synergistic interactions between the core and shell. Herein, the preparation of core-shell structured transition metal selenides nanospheres was achieved through a facile wrapping process using zeolitic imidazolate framework (ZIF-67) as the cobalt source, which assembled on glycerol precursor nanospheres. After a selenization treatment, this formed core-shell structure had a Ni-MoSex inner core, supporting the CoSe2 outer shell (denoted as Ni-MoSex@CoSe2 CSNs). And the resultant Ni-MoSex@CoSe2 CSNs not only had a large number of active sites, but also was good for adsorbing/transferring iodine and hydrogen ions. Therefore, Ni-MoSex@CoSe2 delivered superior performance in dye-sensitized solar cells (DSSCs) and alkaline hydrogen evolution reactions (HERs). DSSCs based on Ni-MoSex@CoSe2 CSNs performed an outstanding power conversion efficiency (PCE) of 9.58% which was much higher than that of Pt (8.32%). A lower onset potential of 37.5 mV and a smaller Tafel slope of 68.9 mV dec?1 were achieved by Ni-MoSex@CoSe2 as electrocatalysts for HER in 1.0 M KOH. This work affords a new idea for the design of cut-price core-shell nanomaterials with high efficiency and can be extended to the synthesis of other electrocatalysts substituting Pt-based catalysts.
关键词： Hydrogen evolution,Core-shell nanosphere,Bifunctional catalyst,Dye-sensitized solar cell,Ni-MoSex@CoSe2,Transition metal selenide
更新于2025-09-19 17:13:59