Synthesis of high-entropy alloy nanoparticles on supports by the fast moving bed pyrolysis

Abstract

High-entropy alloy nanoparticles (HEA-NPs) are important class of materials with significant technological potential. However, the strategies for synthesizing uniformly dispersed HEA-NPs on granular supports such as carbon materials, γ-Al 2 O 3 , and zeolite, which is vital to their practical applications, are largely unexplored. Herein, we present a fast moving bed pyrolysis strategy to immobilize HEA-NPs on granular supports with a narrow size distribution of 2 nm up to denary (MnCoNiCuRhPdSnIrPtAu) HEA-NPs at 923 K. Fast moving bed pyrolysis strategy ensures the mixed metal precursors rapidly and simultaneously pyrolyzed at high temperatures, resulting in nuclei with a small size. The representative quinary (FeCoPdIrPt) HEA-NPs exhibit high stability (150 h) toward hydrogen evolution reaction with high mass activity, which is 26 times higher than the commercial Pt/C at an overpotential of 100 mV. Our strategy provides an improved methodology for synthesizing HEA-NPs on various supports.

Nano High‐Entropy Materials: Synthesis Strategies and Catalytic Applications

“…A fast moving bed pyrolysis (FMBP) method has been developed by Lu and coworkers to synthesize HEA‐NPs immobilized on granular supports, which can be promisingly applied in catalysis and energy conversion fields ( Figure a,b). [ 85 ] HEA‐NPs with a narrow size distribution of 2 nm containing up to ten immiscible elements (Mn, Co, Ni, Cu, Rh, Pd, Sn, Ir, Pt, and Au) was obtained via the pyrolysis of the mixed metal precursors loading on granular supports under 923 K reacting within 5 s. (Figure 6c) This FMBP strategy ensured the simultaneous pyrolysis of the mixed metal precursors and resulted in the high supersaturation of monomers, which induced a burst nucleation and the smaller nuclei formation with uniform phase structure. [ 86–88 ] A quinary (FeCoPdIrPt) HEA‐NPs synthesized by this strategy possess high activity and exceptional stability toward hydrogen evolution in water splitting.…”

“…The uncountable elemental combinations of the HEM platform offer us plenty of possibilities to regulate its surface electronic structure and catalytic performances. Therefore, potential applications of HEM‐NPs in heterogeneous catalysts, such as water electrocatalysis, [ 15,39,53,85 ] oxygen reduction, [ 17,32,78,89 ] carbon dioxide reduction, [ 33 ] NH 3 decomposition, [ 90 ] CO oxidation, [ 21 ] and benzyl alcohol oxidation [ 91 ] have been explored. In the following, we will discuss the recent examples of HEA‐NPs heterogeneous catalysts and investigate the origination of their outstanding performance.…”

The Synthesis and Catalytic Applications of Nanosized High‐Entropy Alloys

“…Recently, Gao et al . presented a FMBP strategy to fabricate denary (MnCoNiCuRhPdSnIrPtAu) HEA−NPs supported on granular supports [22] . FMBP strategy made the particles rapidly pyrolyzed at high temperatures, which facilitated the formation of small nuclei size.…”

“…In 2018, the seminal research on carbothermal shock synthesis of carbon supported HEA nanoparticles (NPs) triggered the pursuit of creative approaches for downsizing HEAs to the nanoscale regime [21] . Since then, various methods, such as fast pyrolysis, solvothermal synthesis and mechanical alloying, have been developed [22–25] . With the advancement of synthesis techniques, progress has hinged on the applications of available HEA−NPs in new research areas [26–30] …”

Engineering sub-2 nm ultrasmall high-entropy alloy nanoparticles with extremely superior performance for hydrogen evolution catalysis

“…Given their tunable composition, electronic structure, and significant stability in corrosive media, HEAs highly meet the necessary requirements of becoming advanced electrocatalysts. However, HEAs have only recently been researched in electrocatalysis [21][22][23][24][25] , and the characteristics and properties are gradually investigated and disclosed. But the current HEA catalysts are suffering from various challenges.…”