Carbon-supported metal nanoparticles (NPs) comprise an important class of heterogeneous catalysts. The interaction between the metal and carbon support influences the overall material properties, viz., the catalytic performance. Herein we use and transmission electron microscopy (TEM) in combination with X-ray spectroscopy (XPS) to investigate the encapsulation of metallic iridium NPs by carbon in an Ir/C catalyst. Real-time atomic-scale imaging visualizes particle reshaping and increased graphitization of the carbon support upon heating of Ir/C in vacuum. According to TEM results, carbon overcoating grows over Ir NPs during the heating process, starting from . 550 °C. With the carbon overlayers formed, no sintering and migration of Ir NPs is observed at 800 °C, yet the initial Ir NPs sinter at or below 550 °C, i.e., at a temperature associated with an incomplete particle encapsulation. The carbon overlayer corrugates when the temperature is decreased from 800 to 200 °C and this process is associated with the particle surface reconstruction and is reversible, such that the corrugated carbon overlayer can be smoothed out by increasing the temperature back to 800 °C. The catalytic performance (activity and stability) of the encapsulated Ir NPs in the hydrogen evolution reaction (HER) is higher than that of the initial (nonencapsulated) state of Ir/C. Overall, this work highlights microscopic details of the currently understudied phenomenon of the carbon encapsulation of supported noble metal NPs and demonstrates additionally that the encapsulation by carbon is an effective measure for tuning the catalytic performance.
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http://dx.doi.org/10.1021/acsnano.3c10850 | DOI Listing |
ACS Nano
January 2025
Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.
Electrochemical water splitting is a promising method for generating green hydrogen gas, offering a sustainable approach to addressing global energy challenges. However, the sluggish kinetics of the anodic oxygen evolution reaction (OER) poses a great obstacle to its practical application. Recently, increasing attention has been focused on introducing various external stimuli to modify the OER process.
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Laboratorio de Biocatalizadores y sus Aplicaciones, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, Uruguay.
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Prof. Rashidi Laboratory of Organometallic Chemistry & Material Chemistry, Department of Chemistry, College of Science, Shiraz University, Shiraz, 7194684795, Iran.
In this study, a Pd nanoparticles@hydrogen-bonded organic framework (Pd NPs@HOF) thin film was fabricated at the toluene-water interface. The HOF was formed through the interaction of trimesic acid (TMA) and melamine (Mel) in the water phase, while Pd(0) was produced from the reduction of [PdCl(cod)] in the organic phase. The as-synthesized Pd NPs@HOF thin film was demonstrated to be an effective catalyst for the selective reduction of -nitrophenol and -nitrophenol to -aminophenol and -aminophenol.
View Article and Find Full Text PDFBioconjug Chem
January 2025
Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
Silica nano/microparticles have generated significant interest for the past decades, emerging as a versatile material with a wide range of applications in photonic crystals, bioimaging, chemical sensors, and catalysis. This study focused on synthesizing silica nano/microparticles ranging from 20 nm to 1.2 μm using the Stöber and modified Stöber methods.
View Article and Find Full Text PDFChemphyschem
January 2025
School of Energy and Power, New Energy, 02 Mengxi Street, 212003, Zhenjiang, CHINA.
Since hydrogen is a promising alternative to fossil fuels due to its high energy density and environmental friendliness, water electrolysis for hydrogen production has received widespread attentions wherein the development of active and stable catalytic materials is a key research direction. This article designs a dual transition metal doped functional graphene for hydrogen evolution reaction via density functional theory calculations. Among varied combinations, 16 candidates are screened out that are expected to be stable as reflected by the criterion of formation energy Ef < 0 and active due to its free energy of hydrogen adsorption ∆GH within the window of ±0.
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