41 research outputs found
Synthesis of Well-Defined, Surfactant-Free Co<sub>3</sub>O<sub>4</sub> Nanoparticles:The Impact of Size and Manganese Promotion on Co<sub>3</sub>O<sub>4</sub> Reduction and Water Oxidation Activity
Abstract: A surfactant-free synthetic route has been developed to produce size-controlled, cube-like cobalt oxide nanoparticles of three different sizes in high yields. It was found that by using sodium nitrite as salt-mediating agent, near-quantitative yields could be obtained. The size of the nanoparticles could be altered from 11 to 22Â nm by changing the cobalt concentration and reaction time. These surfactant-free nanoparticles form ideal substrates for facile deposition of further elements such as manganese. The effect of size of the cobalt oxide nanoparticles and the presence of manganese on the reducibility of cobalt oxide to metallic cobalt was investigated. Similarly, the effect of these parameters was investigated with a visible light promoted water oxidation system with cobalt oxide as catalyst, together with [Ru(bpy) 3] 2+ light harvester dye and an electron acceptor. Graphical Abstract: A novel surfactant-free synthetic route has been developed to produce size-controlled, cube shaped cobalt oxide nanoparticles in high yields. [Figure not available: see fulltext.]. </p
Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles
The aim of this paper was to verify a
possible correlation between the pore-size of meso-
porous silica nanoparticles (MSNs) and the sizes of
gold nanoparticles (AuNPs) obtained by an impreg-
nation of gold(III) chloride hydrate solution in the
MSNs, followed by a specific thermal treatment.
Mesoporous silica nanoparticles with tunable pore
diameter were synthesized via a surfactant-assisted
method. Tetraethoxysilane as silica precursor, cetyl-
trimethylammonium bromide (CTAB) as surfactant
and toluene as swelling agent were used. By varying
the CTABâtoluene molar ratio, the average dimension
of the pores could be tuned from 2.8 to 5.5 nm.
Successively, thiol groups were grafted on the surface
of the MSNs. Finally, the thermal evolution of the gold
salt, followed by ââin situââ X-ray powder diffraction
(XRPD) and thermogravimetric analysis (TGA),
revealed an evident correlation among the degradation
of the thiol groups, the pore dimension of the MSNs
and the size of the AuNPs. The samples were
characterized by means of nitrogen adsorptionâ
desorption, transmission electron microscopy, small-
angle X-ray scattering, XRPD ââin situââ by synchro-
tron radiation, and ââex situââ by conventional tech-
niques, diffuse reflectance infrared Fourier transform
spectroscopy, and TGA
Vibrational density of states and thermodynamics at the nanoscale: the 3D-2D transition in gold nanostructures
Lattice Strain Mapping of Platinum Nanoparticles on Carbon and SnO2 Supports
It is extremely important to understand the properties of supported metal nanoparticles at the atomic scale. In particular, visualizing the interaction between nanoparticle and support, as well as the strain distribution within the particle is highly desirable. Lattice strain can affect catalytic activity, and therefore strain engineering via e.g. synthesis of core-shell nanoparticles or compositional segregation has been intensively studied. However, substrate-induced lattice strain has yet to be visualized directly. In this study, platinum nanoparticles decorated on graphitized carbon or tin oxide supports are investigated using spherical aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM) coupled with geometric phase analysis (GPA). Local changes in lattice parameter are observed within the Pt nanoparticles and the strain distribution is mapped. This reveals that Pt nanoparticles on SnO(2) are more highly strained than on carbon, especially in the region of atomic steps in the SnO(2) lattice. These substrate-induced strain effects are also reproduced in density functional theory simulations, and related to catalytic oxygen reduction reaction activity. This study suggests that tailoring the catalytic activity of electrocatalyst nanoparticles via the strong metal-support interaction (SMSI) is possible. This technique also provides an experimental platform for improving our understanding of nanoparticles at the atomic scale
The 2022 solar fuels roadmap
Funder: Alfred P. Sloan Foundation; doi: http://dx.doi.org/10.13039/100000879Funder: Thistledown FoundationFunder: Research Corporation for Science Advancement; doi: http://dx.doi.org/10.13039/100001309Funder: TomKat Foundation; doi: http://dx.doi.org/10.13039/100018042Funder: Taiwan Ministry of Education and Taiwan and Ministry of ScienceFunder: the Netherlands Ministry of Economic Affairs and Climate PolicyFunder: Nederlandse Organisatie voor Wetenschappelijk Onderzoek; doi: http://dx.doi.org/10.13039/501100003246Abstract
Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.</jats:p
Optically understanding the dependence of catalysis kinetics on work function of nanocatalyst
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The 2022 solar fuels roadmap
Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field