In Situ Observation of Metal to Metal Oxide Progression: A Study of Charge Transfer Phenomenon at Ru–CuO Interfaces

Abstract

Surface charge and charge transfer between nanoclusters and oxide supports are of paramount importance to catalysis, surface plasmonics, and optical energy harvesting areas. At present, high-energy X-rays and theoretical investigation are always required to determine the chemical state changes in the nanoclusters and the oxide supports, as well as the underlying transfer charge between them. This work presents the idea of using chrono-conductometric measurements to determine the chemical states of the Ru nanoclusters on CuO supports. Both icosahedral and single-crystal hexagonal close-packed Ru nanoclusters were deposited through gas-phase synthesis. To study the charge transfer phenomenon at the interface, a bias was applied to cupric oxide nanowires with metallic nanocluster decoration. In situ conductometric measurements were performed to observe the evolution of Ru into RuO x under heating conditions. Structural elucidation techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, and Kelvin probe force microscopy were employed to study the corresponding progression of structure, chemical ordering, and surface potential, respectively, as Ru(0) was oxidized to RuO x on the supporting oxide surface. Experimental and theoretical investigation of charge transfer between the nanocluster and oxide support highlighted the importance of metallic character and structure of the nanoclusters on the interfacial charge transfer, thus allowing the investigation of surface charge behavior on oxide-supported catalysts, in situ, during catalytic operation via conductometric measurements.

NanoMaterialsCAD: Flexible Software for the Design of Nanostructures

“…The methodology is described in detail in the Supporting Information and in refs. [ 26 and 27 ] . Figure 5b shows a charge density transfer plot of the system, that is, a projection on the x – z plane of the total charge density difference between the overall structure (i.e., the relaxed Pt NP resting on the CuO NW) and its corresponding isolated constituents (i.e., the relaxed Pt NP and the bare CuO NW surface).…”

“…Surface charge and charge transfer between metallic NPs and metal-oxide supports are of great importance for various applications in catalysis, surface plasmonics, electrochemistry, etc. [26,27,48] Especially in the field of chemical (bio-) sensing, the nature of the NP-oxide support interface and the resulting interactions can determine the sensitivity and selectivity of the sensor device. [49][50][51] Ab initio theoretical studies based on reallife experimental data are often necessary to characterize these interfaces accurately.…”

“…Of particular significance has been the demand to reproduce surfaces and interfaces obtained from microscopy characterization of experimental samples, because of their importance in the determination of, e.g., electronic structures and chemical, magnetic, or plasmonic properties, etc. [ 21,22,26–28 ] With this work, we are introducing our newly developed software, NanoMaterialsCAD, [ 29 ] which caters for such needs. It is a free tool for modeling and manipulation of nanoobjects at the atomic level that provides an easy and automated way to create various kinds of crystalline structures such as nanoparticles, nanodots, nanowires, nanotubes, nanoscrolls, spatial vacuums, etc., all packed into a single integrated application.…”

Atomic-scale structure and chemical sensing application of ultrasmall size-selected Pt nanoparticles supported on SnO2

“…Magnetron sputtering inert-gas condensation, a versatile technique for the growth of single-and multicomponent nanoparticles with controlled size and morphology, [21][22][23] was employed for the deposition of pre-formed, size-selected Pt nanoparticles. A wide range of nanoparticle functionalities has been achieved with this method, e.g., percolating nanoparticle films for chemoresistive sensing, [24][25][26][27][28][29][30] nanoparticle-decorated metal oxide nanowire devices for chemoresistive sensing, [31][32][33] supported nanoparticles for catalysis and electrochemistry, [34][35][36][37] magnetic nanoparticles, 30,[38][39][40] nanoparticles embedded in multi-layered anodes for lithium ion batteries 41 and nanoportals for hydrogen storage applications. 42 Here, we demonstrate a new approach for the surface functionalization of micro-machined chemical sensor devices realized in complementary metal-oxide-semiconductor (CMOS) technology, in particular by depositing ultrasmall Pt nanocatalysts by magnetron sputtering inert-gas condensation onto nanocrystalline SnO 2 thin films integrated on a suspended microhotplate platform.…”

Nickel Alloying Significantly Enhances the Power Density of Ruthenium‐Based Supercapacitors

“…[17] Furthermore, elaborate synthesis procedures have been developed to generate the required high surface areas facilitating effective ion diffusion at highfrequencies. [10,18,19] However, as material loading increases, ion diffusion becomes less efficient, effectively limiting the use of EDLC-based materials in high-frequency SC applications. [16] Pseudocapacitive materials, such as MnO 2 , [20] RuO 2 , [21] metalorganic frameworks, [22][23][24] and MXene [25] exhibit high capacitance density making them promising candidates for highfrequency SCs.…”