High-Entropy Perovskite Fluorides: A New Platform for Oxygen Evolution Catalysis

Abstract

High-entropy perovskite fluorides (HEPFs) have great potential in electrocatalysis that has not been realized because of the limitation of a high-temperature synthetic route and the limited understanding of high-entropy materials. The use of HEPFs in effective oxygen evolution catalysis and a feasible synthesis route for HEPFs in a boiled solution by combining a hydrothermal method with mechanochemistry are first reported here. These HEPFs consisting of cost-effective elements dramatically gave excellent catalytic activity for the oxygen evolution reaction in an alkaline media.

Nano High‐Entropy Materials: Synthesis Strategies and Catalytic Applications

“…Using cheap metal sulfates instead of expensive fluorides, Dai and coworkers manufactured a class of ABF 3 -type potassium-based HEP fluorides (K-HEPFs) with a single perovskite phase. [45] A dual-phase perovskite, TiZrHfNbTaO 11 , including 60 mol% AB 2 O 7 monoclinic perovskite and 40 mol% of A 6 B 2 O 17 orthorhombic perovskite, was synthesized by mechanochemistry followed by high-pressure torsion method and high-temperature oxidation. [46] This two-phase oxide showed an appreciable light absorbance in the visible-light region with an appropriate valence and conduction bands for water splitting.…”

“…HEAs can be manufactured by physical mixing and mechanical alloying methods through ball milling of the metal powders with the process controlling agents. [ 18,25,43–46 ] A composite of HEA‐NPs and few‐layer graphene was first reported by Rekha et al via ball milling process following the graphene exfoliation. [ 47 ] The as‐synthesized NiCrCoCuFe HEA‐NPs showed a FCC structure and the composite exhibited excellent corrosion resistance.…”

Mechanochemical synthesis of novel rutile-type high entropy fluorides for electrocatalysis

“…Inorganic metal fluorides find applications in catalysis, as electrode active materials, as superconducting devices, as corrosion protection etc. [18][19][20][21] Non-binary compounds, like Co doped MgF 2 , can show additional properties, like in the mentioned case the modification of surface acidity properties whilst maintaining the rutile phase. 22 Ternary metal fluorides for instance, AgCuF 3 , 23 Cu x Fe 1-x F 2 or Li 3 MF 6 (M=V, Cr, Mn, Co, Fe) demonstrate reversible conversion reactions with Li-ions, [24][25][26] rendering them as potential energy storage materials.…”

“…31,32 First reports about rare-earth-based fluorite and perovskite structured high entropy fluorides and rock-salt structured oxyfluorides have shown promising properties for energy storage, optical and catalytic properties. 6,16,18 Wang et al reported that the existence of weak bonds between transition metal (TM)fluoride species, intrinsic structural defects and a distortion of the HEM lattice due to different TM constituents, can provide enhanced oxygen evolution reaction (OER) activity. 18 Due to their special electronic configuration and surface complexity, HEMs are in general expected to provide desirable electrocatalytic properties.…”

“…6,16,18 Wang et al reported that the existence of weak bonds between transition metal (TM)fluoride species, intrinsic structural defects and a distortion of the HEM lattice due to different TM constituents, can provide enhanced oxygen evolution reaction (OER) activity. 18 Due to their special electronic configuration and surface complexity, HEMs are in general expected to provide desirable electrocatalytic properties. 33,34 In the present work, we detail the synthesis and an in-depth characterization of multi-cationic (with 4 to 7 cations) composed rutile (P4 2 /mnm) structured medium-(4 cations) and high-entropy (5-7 cations) fluorides (MEF and HEFs, respectively).…”