Simultaneous Multication Exchange Pathway to High-Entropy Metal Sulfide Nanoparticles

Abstract

High entropy materials, which contain a large number of randomly distributed elements, have unique catalytic, electrochemical, and mechanical properties. The high configurational entropy of the randomized elements drives the formation of high entropy materials; therefore, high temperatures and quenching are typically required to stabilize them. Because of this, colloidal nanoparticles of high entropy materials are difficult to synthesize and remain rare, despite their desirable high surface areas and solution dispersibilities. Here, we introduce simultaneous multication exchange as an alternative low-temperature pathway to colloidal nanoparticles of high entropy materials. Roxbyite Cu_1.8S nanoparticles react with a substoichiometric mixture of Zn²⁺, Co²⁺, In³⁺, and Ga³⁺ to produce nanoparticles of the high entropy metal sulfide Zn_0.25Co_0.22Cu_0.28In_0.16Ga_0.11S. The Zn_0.25Co_0.22Cu_0.28In_0.16Ga_0.11S nanoparticles are thermally stable, and exchange reactions using fewer cations do not produce the high entropy phase. The use of colloidal nanoparticle cation exchange as a synthetic platform provides both entropic and enthalpic driving forces that, in addition to configurational entropy, enable the formation of high entropy phases at solution-accessible temperatures.