We report the first use of NiO, FeO, TiO, and CoO nanoparticles as surfaces for surface-assisted laser desorption/ionization (SALDI) mass spectrometry of asphaltenes. Higher ratios (S/Ns) for asphaltene species were observed using NiO and FeO nanoparticles for SALDI as compared to LDI, where both surfaces consistently provided 2- to 3-fold improved S/Ns. The new SALDI detection method showed reliable adsorption data measuring supernatant solutions after 24 hour asphaltene adsorption on NiO, FeO, and CoO. These results indicated that NiO has a higher adsorption affinity than FeO and CoO for asphaltene molecules, corroborating reported asphaltene adsorption on metal oxide nanoparticles.
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http://dx.doi.org/10.1080/10916466.2017.1370476 | DOI Listing |
ACS Omega
June 2024
Department of Energy Science and Engineering, DGIST, Daegu 42988, Korea.
Water electrolysis for clean hydrogen production requires high-activity, high-stability, and low-cost catalysts for its particularly sluggish half-reaction, the oxygen evolution reaction (OER). Currently, the most promising of such catalysts working in alkaline conditions is a core-shell nanostructure, NiFe@NC, whose Fe-doped Ni (NiFe) nanoparticles are encapsulated and interconnected by N-doped graphitic carbon (NC) layers, but the exact OER mechanism of these catalysts is still unclear, and even the location of the OER active site, either on the core side or on the shell side, is still debated. Therefore, we herein derive a plausible active-site model for each side based on various experimental evidence and density functional theory calculations and then build OER free-energy diagrams on both sides to determine the active-site location.
View Article and Find Full Text PDFDalton Trans
March 2024
Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf, Germany.
A newly synthesized series of bimetallic CPM-37(Ni,Fe) metal-organic frameworks with different iron content (Ni/Fe ≈ 2, 1, 0.5, named CPM-37(NiFe), CPM-37(NiFe) and CPM-37(NiFe)) demonstrated high N-based specific surface areas of 2039, 1955, and 2378 m g for CPM-37(NiFe), CPM-37(NiFe), and CPM-37(NiFe), having much higher values compared to the monometallic CPM-37(Ni) and CPM-37(Fe) with 87 and 368 m g only. It is rationalized that the mixed-metal nature of the materials increases the structural robustness due to the better charge balance at the coordination bonded cluster, which opens interesting application-oriented possibilities for mixed-metal CPM-37 and other less-stable MOFs.
View Article and Find Full Text PDFSmall
June 2024
Chemical Technology III; Faculty of Chemistry and CENIDE, Center for Nanointegration, University of Duisburg-Essen, Carl-Benz-Straße 199, 47057, Duisburg, Germany.
Simultaneous electroreduction of CO and HO to syngas can provide a sustainable feed for established processes used to synthesize carbon-based chemicals. The synthesis of MO/M-N-Cs (M = Ni, Fe) electrocatalysts reported via one-step pyrolysis that shows increased performance during syngas electrosynthesis at high current densities with adaptable H/CO ratios, e.g.
View Article and Find Full Text PDFSci Adv
September 2023
Department of Chemical and Materials Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
High-entropy oxides (HEOs) have aroused growing interest due to fundamental questions relating to their structure formation, phase stability, and the interplay between configurational disorder and physical and chemical properties. Introducing Fe(II) and Mn(II) into a rocksalt HEO is considered challenging, as theoretical analysis suggests that they are unstable in this structure under ambient conditions. Here, we develop a bottom-up method for synthesizing Mn- and Fe-containing rocksalt HEO (FeO-HEO).
View Article and Find Full Text PDFJ Am Chem Soc
October 2023
Department of Interface Science, Fritz-Haber-Institute of the Max-Planck Society, 14195 Berlin, Germany.
The activity of Ni (hydr)oxides for the electrochemical evolution of oxygen (OER), a key component of the overall water splitting reaction, is known to be greatly enhanced by the incorporation of Fe. However, a complete understanding of the role of cationic Fe species and the nature of the catalyst surface under reaction conditions remains unclear. Here, using a combination of electrochemical cell and conventional transmission electron microscopy, we show how the surface of NiO electrocatalysts, with initially well-defined surface facets, restructures under applied potential and forms an active NiFe layered double (oxy)hydroxide (NiFe-LDH) when Fe ions are present in the electrolyte.
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