Extreme mixing in nanoscale transition metal alloys

Abstract

Conventionally, alloys are mostly synthesized in the region of easy mixing, i.e., with light immiscibility and oxidation potentials. Yet such a limited elemental combination largely hinders possible tunability and material discovery. By using entropic design (high temperature and high entropy) that favors uniform mixing, we extended nanoscale alloying to previous unmixable regions by including strongly immiscible and easily oxidized combinations, which we called an extreme mixing. The new alloy space could bring forth exotic nanomaterials for broad applications.

High‐Entropy‐Alloy Nanoparticles with Enhanced Interband Transitions for Efficient Photothermal Conversion

“…However,t he phase-separation will occur when the composited elements exceeding three. [22][23][24] Additionally,o ther synthesis techniques,i ncluding mechanical milling [25][26][27] and carbon-thermal shock, [15,16,28] have significantly shifted the compositional space toward quinary high-entropy alloys, indicating that the HEAs could be synthesized via the highenergy and/or high-temperature strategy.T herefore,inspired by those mentioned studies,w eh erein synthesized the nanoscale HEA particles assisted with ah igh-energy-and high-temperature-based strategy,i ncluding mechanical ballmilling and ultrafast-cooling arc-discharged approach.…”

“…Due to the different vapor pressure of each element, the element content exhibits ad eviation from the original HEAMFs. [15,16,32] Subsequently, the mixing entropy (DS mix )o fd ifferent HEANPs has been calculated by the element content based on the EDS results. Forthe HEANPs which composited more than five elements, their DS mix is all above 1.5R, which is in agreement with the high entropy classification (Figure S20, Table S1, Supporting Information).…”

“…To display the superiority,t he current work on photothermal conversion applications,s uch as graphene,G O, carbon nanotubes,p orous carbon, metals, semiconductors,etc.(Ref. [15] to [38] in Supporting Information) have been summarized in Table S3 (Supporting Information) for comparison (Figure 5). Theevaporation rate and photothermal conversion efficiency of the HEANPs reported in this work are 2.26 kg m À2 h À1 and 98.4 %u nder one sun irradiation, respectively,which arrayed highly in these related research works and thus promise as trong potential in photothermal conversed applications (Table S4, Supporting Information).…”

“…[13] One can imagine that if we fill the d electrons above and below Fermi level to the maximum extent, it is theoretically possible to realize full light capture via the strong d-d IBTs.F or this purpose,the ideal absorbers should contain several transition metals with different configurations of d electrons in asingle-phase structure.However, it remains agreat challenge due to the strong immiscibility between the repelling combinations.A lternative,h igh-entropy alloys (HEAs), which are near-equimolar alloys comprising at least five metallic elements,have tailored compositions,structures, and architectures,a nd thereby extraordinary properties. [14][15][16] Moreover,t he salient character of HEAs is their high configurational entropy,w hich allows the resultant materials to exist in astable solid-solution phase. [16] Thus,the HEAs are expected to be potential candidates for extending the strong d-d IBTs into af ull solar spectrum by designing the d band distribution filling above and below Fermi levels.…”

Au-Ru nanoparticles in catalysis, analysis from first-principles calculations

“…The morphology of the BNP can vary from alloy to core-shell and can be mediated by the preparation method as well as the conditions and it is highly influenced by each metal properties (Nasrabadi et al, 2016;Zaleska-Medynska et al, 2016). The alloying or segregation of the two metals in a BNP is affected by the relative strengths of metal-metal bonds, the surface energies of the bulk elements, the difference in the standard reduction potentials of the used metals and the relative atomic sizes (Ferrando et al, 2008;Tojo et al, 2017;Yao et al, 2021). The higher strengths of heteronuclear (M1-M2) over homonuclear (M1-M1, M2-M2) bonds tend to favor the mixing of metals.…”