Reduction-Controlled Atomic Migration for Single Atom Alloy Library

Abstract

Picturing the atomic migration pathways of catalysts in a reactive atmosphere is of central significance for uncovering the underlying catalytic mechanisms and directing the design of high-performance catalysts. Here, we describe a reductioncontrolled atomic migration pathway that converts nanoparticles to single atom alloys (SAAs), which has remained synthetically challenging in prior attempts due to the elusive mechanism. We achieved this by thermally treating the noble-metal nanoparticles M (M = Ru, Rh, Pd, Ag, Ir, Pt, and Au) on metal oxide (CuO) supports with H 2 /Ar. Atomic-level characterization revealed such conversion as the synergistic consequence of noble metalpromoted H 2 dissociation and concomitant CuO reduction. The observed atomic migration pathway offers an understanding of the dynamic mechanisms study of nanomaterials formation and catalyst design.

Competitive Coordination‐Pairing between Ru Clusters and Single‐Atoms for Efficient Hydrogen Evolution Reaction in Alkaline Seawater

“…After carbonization, abundant holes appear on those nanosheets along with the generation and stabilization of Ru single‐atoms, effectively exposing abundant reactive sites and fastening electronic transmission during HER. [ 17 ] Further, very small Ru@ZnFe 2 O x clusters are uniformly dispersed on the carbon surface for Ru 1, n ‐ZnFe 2 O x ‐C. Meanwhile, the high‐resolution TEM (HRTEM) image (Figure 2c and Figure S4, Supporting Information) gives lattice fringes of 0.205 nm, which agree well with the (101) plane of the hcp Ru phase.…”

“…Furthermore, Ru K‐edge XANES spectra display that the valence of the Ru species is very close to RuO 2 (Figure 3d), confirming an oxidation state of the Ru species in Ru 1, n ‐ZnFe 2 O x ‐C. [ 17 ] Figure 3e presents the Ru K‐edge oscillation curves. Relative to RuO 2 , a remarkable reduction of the amplitude of the oscillation for Ru 1, n ‐ZnFe 2 O x ‐C indicates the changed local atomic arrangement in Ru inserted ZnFe 2 O x ‐C.…”

“…Obviously, the electron gained is mainly in the transition metal and O under the interface, indicating that, after Ru cluster incorporation, electrons are transferred from the cluster to the substrate, reducing the interlayer potential barriers and further improvement of HER activity. [ 2,17 ] Interestingly, the competitive coordination‐pairing between Ru clusters and single‐atoms promotes the key H* over Ru sites to achieve a moderate Δ G H* . According to Sabatier theory, under the ideal conditions, an ideal HER electrocatalyst should possess an optimized Δ G H value close to 0 eV.…”

“…Meanwhile, since the active site in the electrolyte can be well‐protected via M‐O‐M (M = metal) ligand, the catalyst could maintain a high durability in long‐term operations. [ 9,16,17 ] Recently, Ru‐based clusters and SACs are believed as the best alternative of Pt‐based catalysts due to the much lower price of Ru, and high similarity in electron structures and intrinsic catalysis activity. [ 16,18 ] However, owing to lack of a restraining force to prevent the aggregation of Ru atoms, it is very difficult to stabilize Ru‐based clusters and single‐atom in catalysts.…”

Uniform dispersion of ultrafine ruthenium nanoparticles on nano-cube ceria as efficient catalysts for hydrogen production from ammonia-borane hydrolysis

“…, within the range of 0.90–2.26 nm with an average particle size of around 1.43 nm. Since hydrogen gas can increase the mobility of the surface atoms of the noble metal, 50 the resulting ruthenium nanoparticles display a much smaller particle size and can be more uniformly dispersed on the CeO 2 surface than those produced by NaBH 4 reduction in solution, indicative of the potentially superior catalytic performance of Ru 1 /CeO 2 –H 2 /Ar compared to Ru 1 /CeO 2 –NaBH 4 . Similar experimental results were reported for ruthenium nanoparticles supported on Co–Ni bimetallic oxides.…”