Chelating Co-reduction Strategy for the Synthesis of High-Entropy Alloy Aerogels

Through a novel chelating co-reductionstrategy, a high-entropyaerogel (HEAA) is synthesized in the aqueous phase at room temperature.Modulation of the metal reduction potential via the addition of achelating agent (EDTA-4Na) that has strong coordination capabilitiesis the key to the synthesis of single-phase solid solutions. ThisHEAA has excellent HER catalytic properties. Aerogels, as three-dimensional porous materials, haveattractedmuch attention in almost every field owing to their unique structuralproperties. Designing high-entropy alloy aerogels (HEAAs) to quinaryand above remains an enormous challenge due to the different reductionpotentials and nucleation/growth kinetics of different constituentmetals. Herein, a novel and universal chelating co-reduction strategyto prepare HEAAs at room temperature in the water phase is proposed.The addition of chelators (ethylenediaminetetraacetic acid tetrasodiumsalt, sodium citrate, salicylic acid, and 4,4 & PRIME;-bipyridine)with a certain strong coordination capacity can adjust the reductionpotential of different metal components, which is the key to synthesizesingle-phase solid solution alloys successfully. The optimized AgRuPdAuPtHEAA can be an excellent electrocatalyst for hydrogen evolution reaction(HER) with an ultrasmall overpotential of 22 mV at 10 mA cm(-2) and excellent stability for 24 h in an alkaline solution. In situ Raman spectroscopy unveils the enhanced hydrogenevolution reaction mechanism of HEAAs. Overall, this work providesa novel chelating co-reduction strategy for the facile and versatilesynthesis and design of advanced HEAAs and broadens the developmentand utilization of multi-elemental alloy electrocatalysts.